ACEVEDO-RODRIGUEZ, PEDRO, Department of Botany, National Museum of Natural History, Washington, DC 20013 USA, The state of floristic inventories in the West Indies

The flora of the West Indies is one of the best known floras of the Neotropics, with  treatments dating from the beginning of colonial times to the present. Numerous individual island floras exist, but a comprehensive flora for the whole region is still lacking. This talk highlights the more relevant literature for the region.

ACKERLY, DAVID^*, WEBB, CAMPBELL and WRIGHT, IAN, Dept of Biological Sciences, Stanford University, dackerly@stanford.edu, Phylogenetic ecology of tropical trees: the distribution of functional diversity.
The phylogenetic distribution of ecological diversity is poorly known for plants in general, and tropical trees in particular. As part of an NCEAS working group, we compiled functional trait data for tropical tree species from Mexico to Bolivia, including specific leaf area (N = 220 species), wood density (N = 625), effective leaf size (N = 1382), seed size (N = 1697), and mature height (N = 1360). Using the automated web utility Phylomatic, phylogenies were constructed for each of these data sets, based on recent molecular phylogenetic studies of seed plants. A new software package (Phylocom) was then used to evaluate major patterns in the phylogenetic distribution of these ecological traits. We were particularly interested in trends 'above' the family level, as ecologists are less familiar with these higher level groupings. All traits exhibit highly significant patterns of phylogenetic conservatism (an overall trend for closely related species to be ecologically similar). Many novel and highly significant trends were found in deep clades. For example, eurosid 1 (malpighiales, fabales, rosales, etc.) has high wood density and small leaves, while eurosid 2 (malvales, sapindales, etc.) has low wood density. Overall the two eurosid groups include taller species, while the euasterids (Gentianales, Solanales, Asterales, etc.) tend to be shorter. These patterns represent significant trends in average trait values, but there is wide overlap between groups indicating that they are not due to absolute constraints on trait evolution. As these large clades have extensive species and ecological diversity outside the tropics, these trends are probably due to local evolutionary and ecological sorting processes in the Neotropical tree flora. These results, combined with phylogenetic patterns in forest community structure, may provide valuable insights into understanding the assembly and dynamics of tropical forests.

AGUILAR MENA, ZORNITZA^*, Carapungo C 2 O 15, pardali3677@yahoo.com / pardali@hotmail.com, Community level Flowering in a Tropical Rain Forest of the Ecuadorian Amazon.
The flowering at community level, in Yasuni (Norwest of Ecuador), show three periods: Active (mid July to December), Intermediate (June to beginning of July and from January to the first half of February) and Low flowering (second half of February to May). The active flowering period has an inverse relation with rainfall. In this period are high numbers of trees and lianas in flower, but in alternate form. The tallest trees (> 20 m) determine the intensity in flowering time in the forest to produce more flowerings structures, while, the medium canopy trees (10-20 m) have mayor diversity. The flowering times in the plateaus are different that slopes and valley because it have more stress by the moisture viability. I found related species showed synchronous flowering but the timing when the flowers open differs within a few day u hours as a strategy to avoid pollinator competition.

AGUIRRE, ARMANDO^* and DIRZO, RODOLFO, Instituto de Ecologia UNAM Circuito exterior Anexo Jardin Botanico, aguirre@ecologia.unam.mx, Effects of habitat fragmentation on reproductive success and germination in Astrocaryum mexicanum in Los Tuxtlas, Mexico.
We evaluated if tropical forest fragmentation affects the reproductive success (fruit set), and germination potential of the neotropical palm A. mexicanum, by comparing six fragments of varying size (0.3-640 ha) in Los Tuxtlas. We already know that fragmentation negatively affects total number of visitors and pollinators. Small fragments have less pollinators than the largest fragments. Following these results we tested if the diminish in pollinator affect the reproductive success. For two years, we collected 20 infrutescences from randomly selected plants located in 600 m2 plots established in the center of each fragment, and quantified fruit set (number of female flowers/number of fruits per infrutescence). We also evaluated the number of fruits aborted. For germination we randomly selected 10 fruits per infrutescence from 20 plants per fragment. Seeds were placed in a shadehouse. Results show that reproductive success was not significantly affected by fragmentation, in both years (R² = 0.16, P < 0.41; and R² = 0.08, P < 0.56), The number of abortions and germination percentage of did not vary significantly between fragments. We conclude that fragmentation did not affect these reproductive parameters and proposed that, since pollinators are very abundant, pollen availability is guaranteed. if that is the case, however, most pollen is likely to be from the same fragment, given that pollen flow between fragments is restricted due to the reduced vagility of the plants' small pollinators. If this is true, we expect consequences on the genetic variability of the plants surviving in the remnants. We are currently examining this expectation.

AIME, M. CATHERINE^*, HENKEL, TERRY and CHIN, MIMI, USDA-ARS, Systematic Botany and Mycology Lab, 10300 Baltimore Ave., Rm. 319, B011A, cathie@nt.ars-grin.gov, Ectomycorrhizal and saprotrophic fungal diversity in western Guyana.
Ectomycorrhizal (EM) fungi form mutualistic symbioses with select groups of woody seed plants and are well represented in temperate and boreal forests. These ecologically important fungi are, however, poorly known from Neotropical forests, particularly those of South America. In Guyana, the Upper Potaro River Basin is characterized by scattered forests dominated by the leguminous EM tree Dicymbe corymbosa (Caesalpiniaceae, tribe Amherstieae), interspersed with mixed forests composed of arbuscular mycorrhizal-forming trees more typical of the Guiana Shield. Mycological expeditions to this remote region in the 1990's indicated that a rich, putatively endemic EM mycota was associated with the Dicymbe stands. To more fully investigate the macromycete component of the region's forests, yearly plot studies were undertaken from 2000-2004. More than 150 species of EM fungi have currently been recorded from the D. corymbosa forests, of which >60% are new to science. EM fungi are almost entirely lacking in the mixed forests. More than 500 species of saprotrophic macromycetes have been recorded among the Dicymbe and mixed forests, accounting for ~75% of the macromycete species diversity. Analysis of fungal guild structure suggest that the more tree-diverse mixed forests harbor more host-specific saprotrophic fungi, possibly due to a higher diversity of substrata. Diversity indices indicate higher overall macromycete diversity in the D. corymbosa forests, primarily due to the high proportion of EM fungi. Phylogenetic analyses of individual lineages suggest that fungal population dynamics result from the more ancient EM fungal lineages existing in relative isolation with their EM hosts, and intermittently punctuated by influxes of opportunistic saprotrophs of a more global distribution. The Dicymbe forests of western Guyana constitute a hot spot for EM fungi in the Neotropics.

ALVARADO-RAMOS, LUIS FERNANDO^* and VEGA RIVERA, JORGE HUMBERTO^*, Mariano Jimenez # 408 Col. La Perla, feral@costera.melaque.udg.mx, Breeding biology and first description of nest and eggs of red-breasted chat in Chamela, Jalisco.

We described for the first time the characteristics of the nests and eggs, and provide additional notes of breeding behavior and nesting habitat selection of the endemic Red-breasted Chat (Granatellus venustus). During may-aug 2001-2002, we found and monitored 34 nests in the tropical deciduous forest of western Mexico. Nests were built 30-123 cm above the ground in saplings < 2 m high. We observed clutches of 3 - 4 eggs. Only the female was observed incubating. The incubation period was 14 days, and we estimated the nestling period to be approximately 8 -10 days. Twenty six of the 34 nests were found with eggs or young, 14 were depredated during the egg stage, six during the nestling stage, and nine were successful. Overall nesting success was 15.5 and was similar between years. We did not find differences in nest placement and vegetation structure between successful (12) and depredated (n = 26) nests. Specific nest site characteristics (nest high and concealment) were not found to be associated with nest outcome. At the nest-patch scale (0.04 ha circle around nest), we did find that structural vegetation attributes that may enhance avoidance of predation, such as numerous woody stems, dense understory, and number of deciduous saplings, were significantly higher in successful than depredated nest sites.

ALVAREZ-CLARE, SILVIA^* and KITAJIMA, KAORU, 220 Bartram Hall, Department of Botany, University of Florida, silviacr@ufl.edu, Impact of vertebrate consumption, litterfall,and disease on tree seedling survival in the forest understory.
We evaluated the relative importance of vertebrate consumption, litterfall, and disease on seedling survival rates of eight tropical tree species in the shaded understory on Barro Colorado Island, Panama. Seedlings were raised from seed in a shaded nursery and transplanted at leaf expansion to 100 stations in the shaded understory located randomly along a 9-km network of trails. At each station, one seedling of each species and two artificial seedlings of different sizes made of plastic and wire were planted within a 1 m² area, and examined every 1-2 wks for one year. Species differed in their temporal pattern of survival described by Kaplan-Meier survival functions. During the first two months, species with large reserve cotyledons exhibited high mortality (up to 86 % of transplanted seedlings) due to vertebrate consumption, evidenced by broken or uprooted stems, loss of cotyledons, and damaged leaves. These species improved their survival rates after two months, surviving well when hit by litterfall and exhibiting low levels of disease. Higher stem tissue density and toughness were positively correlated with survival after two months, when disease and damage by litterfall increased their relative importance as mortality agents. On the contrary, shade intolerant species maintained steady mortality rates during the first six months. For the pooled sample of all species, 68% displayed evidence of vertebrate consumption or trampling, 7% were affected by litterfall, and 10% developed leaf disease. Additionally, 50% of the artificial seedlings presented evidence of physical disturbance (smashed, broken or bent) attributed to vertebrate trampling, and 29% were affected by litterfall. In conclusion, vertebrate activities, litterfall, and disease were important causes of seedling mortality, but their relative importance changed rapidly within the first year, causing ontogenetic shifts in species ranking of seedling survival in the understory.

ANDERSON OLIVAS, ELIZABETH, PRINGLE, CATHERINE M. and FREEMAN, MARY C., Organización para Estudios Tropicales, Estación Biológica La Selva, eanderson@sloth.ots.ac.cr, Cumulative effects assessment of dams on hydrologic connectivity in the Sarapiqui River watershed, Costa Rica.
Dams for hydropower are rapidly transforming rivers in tropical regions and changing the landscapes of many countries. In Costa Rica, more than 30 hydropower dam projects have been constructed since the early 1990s, and watersheds with only one or no dams are becoming rare. While studies of the ecological impacts of individual dams have been limited, there have been no attempts to address cumulative impacts of multiple hydropower dam projects on Costa Rican rivers. As dam construction continues in Costa Rica and other parts of the tropics, cumulative effects assessment will be a necessary tool for conservation and management of freshwater systems. In this study, we showed how simple cumulative effects assessment can be accomplished using limited data. We examined the cumulative effects of multiple hydropower dam projects on the hydrologic connectivity of the Sarapiqui River watershed, Costa Rica. Since 1990, eight hydropower dam projects have been built in the watershed and an additional project, Cariblanco Dam, is under construction. We determined that existing projects have fragmented the watershed by dewatering 31 km of streams; the planned Cariblanco Dam will dewater 16 km more. We also calculated that 10 % of total stream km in the watershed is upstream from dams and discontinuous with downstream areas; the Cariblanco Dam will increase that number to 14% of total stream km. Our results suggest that not all hydropower dam projects are the same and that the placement of dams in the watershed, rather than the total number, is important to preserving hydrologic connectivity. Furthermore, the effects of hydropower dam projects may interact with other human disturbances in the watershed, such as deforestation and increasing fishing pressures, to affect ecological integrity.

ARAVIND, N. A.^*, UMA SHAANKER, R. and GANESHAIAH, K. N., ATREE, #659 5th A main, Hebbal, aravind@atree.org, Frog assemblages in threatened Myristica swamp habitat of Western Ghats, India.
The Myristica swamps in the Western Ghats, India are one of the unique and threatened fresh water habitats. Forest fragmentation besides human pressures have led to a loss of many of such habitats and the drying up of these swamps. It is believed that the swamps could form an ideal habitats and refugia for many taxa especially amphibians during the dry seasons. We studied the effect of swamp size and anthropogenic disturbance on frog assemblage in the Myristica swamps. The frogs were sampled using quadrat method. All microhabitat were intensively searched for frogs. A total of 26 species belonging to four families was recorded from the 18 swamps falling to three size category (large, medium and small) and two disturbance class (highly disturbed and less disturbed). The pooled data shows that the large swamps harbors high diversity, richness and abundance compared to medium and small swamps. Similarly, less disturbed swamps are diverse than highly disturbed. There is a very high similarity in frog assemblages between size and disturbance class showing the there is very low turnover of species. However, there is no significant difference between three size category in frog assemblage (F_2,48= 1.25, P=0.295), where as there is significant difference between disturbance category (T test= -2.105, P=0.023). Mean similarity in species composition was significantly different among swamp sizes (F_2,42=6.44, P=0.004). We discuss the implications of the results on the conservation of the Myristica swamps in the Western Ghats.

ARAYA, ANA L.^*, HANSON, PAUL and ROCHA, OSCAR J., Escuela de Biología, Universidad de Costa Rica, Ciudad Universitaria, anarayacr@yahoo.com, Reproductive and vegetative phenology for two populations of Miconia calvescens DC. (Melastomataceae) in Costa Rica: an invasive plant in the Hawaiian and French Polynesia Islands.
The reproductive and vegetative phenology of 47 trees of Miconia calvescens DC. (Melastomataceae) was studied in two populations in Costa Rica from Dec-2001 through Dec-2003. We monitored four phenological stages (budding, flowering, fruiting, and leafing) every three weeks using a semi-quantitative scale. Both years, flower buds and panicles were produced from mid-August to mid-November and flower anthesis occurred from mid-November to mid-December. Fruits started developing almost immediately after flowering and fruit maturation lasted from mid-March through late-April. Vegetative growth starts as fruits mature and is most intense right before the initiation of new flower buds. In 2003, more frequent observations were conducted during the flowering period, and determined that anthesis is synchronized at population and individual level in two episodes that last less than a week, and are separated by two weeks or more. Anthesis coincides with the end of the rainy season and also with a decrease in day length. Observations of a longer period between flowering episodes in one population suggest that rain may delay anthesis. A comparison of these findings with those reported for M. calvescens in Hawaiian and French Polynesia Islands are discussed.

ARDON, MARCELO^*, STALLCUP, LINDSAY and PRINGLE, CATHERINE, Institute of Ecology, University of Georgia, mardon@uga.edu, Influence of substrate quality and water chemistry on decomposition dynamics in lowland neotropical streams.
We tested the hypothesis that water chemistry influences leaf breakdown rates in tropical streams draining the Caribbean slope of Costa Rica. In addition we wanted to examine potential interactions between water chemistry and leaf litter chemistry. Principal Component Analysis (PCA) was used to select three common riparian tree species (Trema integerrima, Castilla elastica and Zygia longifolia) that had similar initial carbon and nitrogen concentrations but represented a wide range of chemical parameters in regards to secondary (phenolics and tannins) and structural (cellulose, hemicellulose and lignin) compounds. Leaf bags were incubated in six streams that have different water chemistry due to the influence of solute-rich geothermal inputs. In particular we were interested in the streams dissolved phosphorus concentrations: three streams had low natural concentrations (less than 15Μ g/L), two had high natural concentrations (100 Μg/L) and a whole stream phosphorus enrichment experiment (more than 200 Μg/L) was used to isolate phosphorus effects from other geothermal input solutes. Decay rates were higher in streams receiving geothermal inputs and in the P-enrichment stream for all three species. Both phosphorus and flow velocity appeared to affect decay rates and effects were different among species. Fungal biomass was higher in solute rich streams and in the enrichment experiment only for Trema, the highest quality species. Microbial respiration was significantly higher in a solute rich stream and the enrichment stream on two of the species (Trema and Castilla), but not on the lowest quality species (Zygia). Increases in decay rates, fungal biomass and microbial respiration were all comparable in the high solute and the P-enrichment stream, supporting the hypothesis that dissolved phosphorus (SRP) was a causal factor. Results indicate that initial litter chemical characteristics of the species mediate biotic, and therefore breakdown, response to water chemistry.

ARIAS-CÓYOTL, ETHEL^*, STONER, KATHRYN E., CASAS, ALEJANDRO, CRUSE-SANDERS, JENNIFER and QUESADA, MAURICIO, CIEco, UNAM, Apartado Postal 27-3, kstoner@oikos.unam.mx, Effectiveness of nectar-feeding bats as pollinators of Stenocereus stellatus in cultivated, managed and wild populations in Chinango, Oaxaca.
Stenocereus stellatus is a self-incomplatible bat-pollinated columnar cactus endemic to central Mexico that is used for human food, firewood, living fences and forage. In the region of Chinango, Oaxaca it is found in three types of populations. Cultivated home gardens (C), managed wild populations (M) found in silvicultural and agriculture areas with plants selectively left in place, and wild populations (W) in undisturbed areas of tropical dry forest. The objectives were to: 1) compare the feeding patterns of the nectar-feeding bats within cultivated, managed, and wild populations and 2) analyze the relationship between the feeding patterns with the reproductive success of the plants. Feeding patterns were documented by filming flowers from anthesis to sunrise. Reproductive success was estimated with the parameters of fruit set, fruit size, and number of seeds produced. Leptonycteris curasoae, L. nivalis and Choeronycteris mexicana were effective pollinators of S. stellatus making contact with both stigma and anthers during all visits. Flowers from plants in cultivated populations received significantly fewer visits than managed or wild populations. The number of effective visits that a flower received did not determine the size of the fruit or the number of seeds. In spite of the fact that cultivated populations had significantly fewer visits than managed or wild populations, fruit production was significantly higher in cultivated (70%), than managed (34%) or wild (37%) populations. Thus, the higher visitation rate observed in managed and wild populations does not appear to promote a higher reproductive rate. This phenomenon may be explained because the quality of pollen that is transported by bats in these areas may be reduced due to the fact that resources are more isolated and territorial feeding behavior, typical of Leptonycteris spp., may reduce outcrossing. Cultivated populations likely function as an important resource corridor that connects fragmented populations of S.stellatus.

ARISTIZABAL, CATALINA^* and JANOS, DAVID P., University of Miami, Department of Biology, P.O. Box 249118, cataad@bio.miami.edu, Litter quality affects the colonization of decomposing leaves by arbuscular mycorrhizal fungi.

Recently, we have shown that arbuscular mycorrhizal fungi (AMF) spread within the slowly decomposing leaves of Myrica pubescens, M. parvifolia, and Paepalanthus sp. at montane sites in Colombia. Whether or not this phenomenon occurs widely in other plant species and ecosystems, and how it is influenced by litter quality are not known. To assess the effect of litter quality on the colonization by AMF of decomposing leaves, we buried 60 micron mesh bags individually containing dried leaves of five different species in a South Florida, sub-tropical broadleaf hammock at the University of Miami Smathers Biology Field Station. These leaves, categorized either as recalcitrant (R) or labile (L), were from M. cerifera (R), Quercus virginiana (R), Rhapis excelsis (R), Averrhoa carambola (L), and Costus sp. (L). Bags were distributed in randomized complete blocks that were harvested after 70, 100, 170, and 400 days. We found that although AMF could colonize leaf litter of different qualities, the rates of colonization differed. Soft, high-quality, labile leaf litter was colonized rapidly, but recalcitrant leaves were colonized slowly. This experiment suggests that litter quality may influence the efficiency of nutrient capture by arbuscular mycorrhizal fungi, thereby affecting ecosystem-level nutrient cycling.

ARNOLD, A. ELIZABETH^*, Department of Biology, Duke University, aearnold@duke.edu, High molecular diversity of foliar endophytes associated with leaves of tropical trees.
Fungal endophytes inhabiting healthy leaves of tropical trees comprise a trove of poorly known species diversity, and therefore, a remarkable quantity of unexplored genetic diversity. I assessed endophyte infections in leaves of seven species of woody angiosperms in Panama with the goals of determining (1) the taxonomic placement of common endophytes associated with each host; (2) genotypic diversity within and among common morphotaxa; (3) the role of increased sampling in recovering previously unrecorded endophyte taxa; and (4) the importance direct PCR in assessing endophyte community structure. Endophytes were isolated on malt extract agar from three asymptomatic, mature leaves of a basal Eudicot (Heisteria concinna, Olacaceae), four Eurosids (Ouratea lucens, Ochnaceae; Laetia thamnia, Flacourtiaceae; Swartzia simplex, Caesalpiniaceae; Trichilia tuberculata, Meliaceae), and two asterids (Gustavia superba, Lecythidaceae; Faramea occidentalis, Rubiaceae). The nrDNA internal transcribed spacer (nrITS) was sequenced for 10 representative isolates per host species, all endophytes isolated from a focal host (L. thamnia; N = 55 isolates), and a subset of clones generated from in situ PCR of surface-sterilized leaf tissue. Phylogenetic analyses indicated that the most common endophytes are filamentous Ascomycota, including Xylariaceae, Phyllachoraceae, Botryosphaeriaceae, Nectriacae, Valsaceae, Calosphaeriaceae, and a lineage with no close relatives in GenBank. Genotypic diversity, estimated at 90% sequence similarity using global comparisons of homologously delimited sequences, indicated that most morphotypes contained multiple nrDNA genotypes. Accordingly, the genotype-accumulation curve outpaced that of morphotaxa, suggesting that morphotypes underestimate the richness of tropical endophyte communities. Many nonsingleton genotypes were restricted to particular host species, but some were common to multiple hosts. Thorough sampling of L. thamnia yielded several new records, including a chaetothyrialean fungus pathogenic to insects. Additional, uncultured lineages were encountered through in situ PCR (e.g., Ustilaginomycetes). Implications for our understanding of endophyte ecology, evolution, and community structure are discussed.

ARROYO-MORA, JUAN PABLO^*, SÁNCHEZ-AZOFEIFA, G. ARTURO, RIVARD, BENOIT, CALVO, JULIO C. CALVO and JANZEN, DANIEL H., Department of Earth and Atmospheric Sciences, EOSL, University of Alberta, arturo.sanchez@ualberta.ca, Fragmentation analysis for the Chorotega region, Costa Rica from 1960 to 2000.
We analyzed landscape dynamics for the Chorotega region, Costa Rica over the last 40 years (1960-2000). Fragmentation was caused by extensive cattle ranching practices for the first two decades, whereas forest recovery (during the last two decades) was the result of abandonment of pasture lands due to changes in the country's economy and the development of new conservation policies. The study area has a deforestation rate of -2.76 percent from 1960 to 1979. However, from 1979 to 1986 and from 1986 to 2000 recovery rates of 1.63 and 4.91 percent respectively, were observed. Besides the dramatic reduction in forest area between 1960 and 1979, fragmentation metrics for this period showed a decrease in the number of patches and mean and median patch size; while edge density remained nearly constant and mean shape index increased. Subsequently, results of the forest recovery process for the whole area indicate an increase in forest area, number of patches (1976-1986) mean and median patch size (1986-2000), mean shape index (1979-2000) and edge density (1979-1986). A detailed fragmentation analysis at the land use capability level (Costa Rican methodology to classify land use capability based on biophysical characteristics) shows that the forest areas located in the agricultural class experienced more deforestation and less forest recovery than any other class. The similar trend shown by fragmentation metrics for marginal classes is an indicator of a gradient in their land use history. As biophysical conditions become more challenging for agricultural practices, less human impact is apparent along with faster recovery. In terms of conservation and considering the potential impacts The Central America Free Trade Agreement (CAFTA) may have, Costa Rica needs to focus on the management and consolidation of forest areas within the agricultural matrix if the country does not want to repeat past deforestation experiences.

ARTAVIA-MATA, MAYRELITH^*, HERRERA, JORGE, HANSON, PAUL and ROCHA, OSCAR J., Escuela de Biología., Universidad de Costa Rica., mayrel@costarricense.cr, Seed ecology of an invasive plant in its native habitat; the case of Miconia calvescens in Costa Rica.
Miconia calvescens DC. (Melastomataceae) is a native tree from the Neotropics. It was introduced into Hawaii and Tahiti where it became invasive, and is currently a major threat for their native flora. Although there is some information about the biology of this species in these islands, little is known about it in its native range. Here, we studied the seed and seedling dynamics of this species in two populations in Costa Rica. We found that the probability of germination in the field was significantly different between populations after three months (46.5±8.9% in Cariblanco and 36.7±6.7% in Turrialba). Germination in the laboratory was higher than that observed in the field (97.8±1.5% and 88.5±2%; respectively). We also evaluated the effect of ingestion by birds on germination, and found no difference between control and treatment, in both cases, germination was around 90%. Seed survivorship in the soil was estimated by placing bags with seeds over the soil and taking samples every three months. After six months more than 50% of seeds germinated in the field, and there were no significant differences between populations or periods. However there were significant differences in the proportion of dormant seeds between the two populations (40% in Cariblanco, 18% in Turrialba). In addition, our study showed that the use of fungicide did not affect seeds mortality in the field. We also examined seedlings survivorship in open areas (light) and in forest understory (shade). Survivorship showed a clear difference between treatments after three months. Seedlings sown at light environments showed a higher survivorship (97±1.7%) than those in shaded environments (52±23%). Seedling growth, as indicated by the increase in stem diameter was significantly different for the two treatments in one population (0.56±0.38mm at light, and 0.38±0.38mm at forest understory). Implications for the adequate management of this invasive species are discussed.

AVELINO, ALEXANDRE S., DE ANDRADE, BRUNNO S. and HAY, JOHN D.^*, Departamento de Ecologia, Universidade de Brasilia, Campus Universitario Darcy Ribeiro, jhay@unb.br, Relation between size and reproductive effort in Lychnophora ericoides (Asteraceae) in central Brazil.
Lychnophora ericoides is an endemic species in the Cerrado and occurs in patches of a few to several thousand individuals. The blooming season may vary among populations, but in general is between January and March, peak of the rainy season in the Central Highlands of Brazil. Within a native population of L. ericoides on the Experimental Station of the University of Brasilia we evaluated the relationship between an individual's size (using architectural characteristics and dry weight) and its reproductive effort (estimated from the number of inflorescences) in two time periods: between July and November of 2003, using data collected on 20 individuals and between January and March of 2004, using data collected on 49 reproductive individuals. Using multiple linear regression, we calculated the relationship between reproductive effort in each time period and the parameters related to the individual's size (total number of live branches, crown area and total dry weight). For the data from the 2003 blooming period the calculated regression was significant (r² = 0.572) as was the regression for the 2004 blooming period (r² = 0.411). In both cases, when outliers were removed from the data sets (two observations from the first period and one from the second), the fit of the regression lines improved (r² = 0.640 and r² = 0.523, respectively). These results indicate that for reproductive individuals of L. ericoides the individual's size may be a relatively good parameter to estimate reproductive effort, even though slightly less accurate during the main reproductive season (January to March) when most of the individuals in the population, independent of their size, are reproductive. The next step in this study will be a comparison of the number and condition of seeds produced in each of these reproductive seasons.

BANACK, SANDRA, AND COX, PAUL ALAN*, California State University, Fullerton, California USA; Institute for Ethnobotany, National Tropical Botanical Garden, Hawaii and Florida USA. Biomagnification of cycad neurotoxins in flying foxes: implications for ALS-PDC in Guam
Historically, The Chamorro people of Guam suffered a devastating paralytic illness, Amyotrophic Lateral Sclerosis- Parkinsonism Dementia Complex (ALS/PDC) at 100 times the incidence rate of ALS elsewhere. Researchers initially focused on the Chamorro custom of eating tortillas made from the seeds of Cycas micronesica, but a link to human disease could not be demonstrated. We have found that flying foxes (Pteropus mariannus mariannus) which feed on the sarcotesta of cycad seeds accumulate the neurotoxic non-protein amino acid BMAA up to 3500 μg/g of their weight. When Chamorro people eat flying foxes during traditional feasts, they are exposed to high levels of the biomagnified neurotoxin. Our work suggests that there is a link between cycads, flying foxes, and neurological disease in the Marianas islands.

BARLOW, JOS, School of Environmental Science, University of East Anglia, Norwich, UK., j.barlow@uea.ac.uk, Wildfires and wildlife: The effects of single and recurrent wildfires on Amazonian avifauna.

ABSTRACT - Fire severity in Amazonian forests is a strong determinant of the resulting

avifaunal community composition, with strong effects evident up to 3 years post-fire. The effects of these low and high severity wildfires are compared with those of other forms of contemporary forest degradation (selective logging and habitat fragmentation) using mist-net data from seven Amazonian studies. In general, fire disturbance was by far the most severe form of forest degradation, with recurrent fires resulting in almost complete community turnover. These analyses demonstrates the importance of preventing the spread of fires in humid tropical forests, although also highlights the need for more research to determine the long-term suitability of large areas of degraded forest for vertebrate populations.

BARRANTES, DANIEL, CASTRO, EMILIO, MACAYA, GABRIEL and ROCHA, OSCAR J.^*, Escuela de Biologia, Universidad de Costa Rica, San Jose 2050, Costa Rica, ojrocha78@hotmail.com, The impact of local extinction on genetic structure of wild populations of lima beans (Phaseolus lunatus) in the Central Valley of Costa Rica.

We examined the impact of local extinction on genetic structure of wild populations of lima beans (Phaseolus lunatus) in the Central Valley of Costa Rica. We studied the genetic structure of the populations present in 13 locations using microsatellite markers. Locations were classified in three groups according to the occurrence of extinction episodes during the previous five years. Locations in the first group were populations that experienced extinction for more than one year, and were later recolonized (recolonize). Locations in the second group were populations that did not experience local extinction during the study, but were cut to experimentally simulate an extinction episode (experimental). Locations in the last group were control populations that did not experience local extinction (control). For each location, genetic diversity from the samples taken from the populations present at two different times was compared. Variation in allele frequencies did not show a clear tendency in all groups of populations.  Our data also revealed changes in the effective number of alleles in the three groups of populations. Locations in the recolonization group tended to show a reduction in the effective number of alleles, and there were only minor changes in effective number of among the experimental populations. The impact of local extinction on the genetic diversity was also determined examining the genetic distance and the level of population differentiation in samples collected at different times in the same location.  Recolonized locations showed the highest level of genetic differentiation (mean _Fst = 0.2769), followed by control locations (mean F_st = 0.0576) and experimental locations (mean _Fst = 0.0189). Similar findings were observed for Nei^'s genetic distance between population (genetic distance = 0.1786, 0.0400 and 0.0037, respectively). The implications of these results for the adequate management of wild populations of crop plants are discussed.

BARUCH, ZDRAVKO^* and JACKSON, ROB, Dpt. Estudios Ambientales. Univ. Simón Bolívar. Aptdo 89000, zbaruc@usb.ve, Responses of tropical native and invader C₄ grasses to clipping, fire and increased atmospheric CO₂.
Invader African grasses have displaced native species in Neotropical savannas and altered community composition, structure and function. The projected future global changes for tropical savannas include increased atmospheric CO₂concentration, a drier climate and more frequent fires. They could further alter the competitive relationship between native and invader grasses. The objective of this study is to quantify the responses of two populations of a widespread native C₄ grass (Trachypogon plumosus) and two African C₄ grass invaders (Hyparrhenia rufa and Melinis minutiflora) to high CO₂ concentration interacting with three savanna stressors: drought, herbivory and fire. Elevated CO₂ increased the competitive potential of invader grasses. Germination and seedling size was promoted in introduced grasses. Under high CO₂ the relative growth rate of young introduced grasses doubles that of the native grass (0.58 vs 0.25 g g^-1 wk^-1). This initial advantage is maintained, further aiding their competitive potential. Watered and water stressed African grasses respond better to high CO₂ (biomass increased 21 to 47 %) than the native grass (biomass decreased 13 to 51 %). The higher water and nitrogen use efficiency of invader grasses would aid their establishment and competitive potential in drier and/or unfertile sites. African grasses recover faster and better after burning and simulated herbivory. These responses would confer additional advantage to invader grasses as climate becomes drier and fires more frequent. The superiority of invader grasses under high CO₂ points towards further increase in their competitive potential and suggest a future increased rate of displacement of the native savannas by grasslands dominated by introduced African grasses.

BASSET, YVES, CORBARA, BRUNO^* and BARRIOS, HECTOR, CANOPY RAFT CONSORTIUM & UNIVERSITE BLAISE-PASCAL, 34 AV. CARNOT, corbara@srvpsy.univ-bpclermont.fr, IBISCA : A large-scale study of the vertical and horizontal distributions of arthropods in a Panamanian rainforest.
In recent years, there has been considerable debate as to whether most arthropod biodiversity occurs in the canopy or in the soil of tropical rainforests. However, to date, no data are extensive enough to convincingly test this contention mostly due to a lack of spatial replications. The project IBISCA (Investigating the BIodiversity of Soil and Canopy Arthropods) aims to improve this state of affairs by examining the relationships between beta diversity and vertical stratification in a Panamanian rainforest. IBISCA uses a variety of techniques in order to conduct canopy level entomological investigations, including: canopy fogging (pyrethrum knockdown), a canopy crane, single rope techniques, and the Canopy Raft and its derivatives (i.e., the Canopy Bubble, Ikos). These different techniques and devices complement each other well and this project represents the first attempt to combine them in a large-scale investigation. They provided spatial replication during a six-week field study in September-October 2003, whilst seasonal replication is being conducted at the crane sites over the course of the year 2004. To date, we have studied the arthropod fauna of eight sites (all less than 2km apart) within the San Lorenzo Protected Area, Panama. The sampling protocols used by IBISCA are based on spatial replication at different canopy/soil sites so that, for the first time, interactions between horizontal and vertical faunal turnover can be explored. A careful selection of focal taxa from different phylogenies and ecological niches may provide valuable information on faunal distributions. Each participating entomologist is responsible for a particular sampling protocol (14 different collecting methods in total) and studies 1-2 focal taxa (approximately 40 focal taxa studied in all). The interpretation of the results (vertical stratification and beta-diversity of the different focal taxa) will be facilitated by the information provided by several supporting studies characterising the sites surveyed (e.g., type of vegetation, canopy thickness, incidence of light, apparent leaf damage, etc.). IBISCA is an initiative of the Canopy Raft Consortium (France) and of the Smithsonian Tropical Research Institute (STRI, USA).

BECK, JENNIFER L.^*, JACKSON, PAULA C.^* and ANDRADE, JOSE LUIS^*, Kennesaw State University, Dept of Biology ,Kennesaw, GA, pjackson@kennesaw.edu, Differences in source water use of the woody vegetation of the Yucatan Peninsula, Mexico.
The purpose of this study was to use stable hydrogen isotope compositions (ΔD) of xylem sap and soil water to determine the source water use of deciduous and briefly deciduous trees in a tropical dry forest of Dzibilchaltun, Mexico. Samples were collected during the dry season in May, 2003. Soil samples for the determination of soil water ΔD, and separate samples for the determination of gravimetric water content (two samples per depth for each) were collected from a soil profile every 5 cm for 100 cm using a soil auger. Mean relative water content of the soil samples was determined by subtracting the dry from the wet soil weight. Water samples were collected from a cenote (naturally occurring water reservoir with limestone walls) in Dzibilchaltun at depths of 3.50 m (three samples) and 7.10 m (six samples). Xylem samples from 5 deciduous and 5 briefly deciduous tree species were collected using a core borer. Two trees were sampled per species, and two xylem samples were taken per tree. All samples for stable isotope analysis were collected in vacuum containers and sent to a Stable Isotope Lab in Cornell (CoBSIL). Probably as a result of periodic cold fronts experienced in the region, for all samples ΔD values were more negative than would be expected for tropical areas ‘values ranged from about -76 ^o/_oo to -137 ^o/_oo’. Mean soil water ΔD values decreased with depth in the soil profile, whereas mean relative water content increased with depth. Although on average deciduous trees had more negative xylem sap signatures (deeper water source) compared to briefly deciduous trees, this difference was not statistically significant (t-test, p=0.83). Potentially for these trees, individual species strategies may be more important than leaf flushing patterns (e.g. deciduous vs. briefly deciduous) in the determination of source water use.

BELL, KRISTEN E.^*, Dept of Biological Sciences, Florida International University, 11200 SW 8 St, kristen.bell@fiu.edu, Influence of forest fragmentation on frog and lizard communities in lowland Costa Rica: preliminary results.
The single greatest threat facing amphibians and reptiles is posed by anthropogenic habitat modification and fragmentation, although the effects of this ongoing process are still imperfectly understood. Forest fragmentation may lead to decline and extirpation of forest interior species, while edge specialists may thrive. However, the response of a given assemblage cannot be predicted based on knowledge of other systems, since responses are influenced by regional factors such as climate, forest type, and current and past land use, as well as by the individual ecologies of the species involved. The conservation potential of small forest patches may be considerable with regard to small reptiles and amphibians, but such assertions must be investigated at the regional level. This study examines patterns in herpetofaunal abundance and distribution in the fragmented landscape surrounding La Selva Biological Station in the Sarapiqui region of Costa Rica, a site with a diverse and relatively well-known herpetofauna. Community structure and population densities of frogs and lizards in fragments of different areas and isolations are compared to reference areas in continuous forest. Sampling will be done over the course of a full year; here the first six months of data are presented. Frogs and lizards were sampled in nine forest fragments (1-7 ha) and in La Selva, a 1500-ha preserve, using diurnal leaf-litter plots and nocturnal transects. After six months of sampling, species richness in fragments (pooled data) was similar to that in La Selva, about forty species; however, the largest number of species found in a single fragment was only twenty-two. Community composition and densities of common species differed between fragmented and intact forest. Eight (21%) of the species were found only at La Selva; however, at least seven species previously described as undisturbed forest specialists were encountered in the fragments. The high diversity observed in the entire set of fragments indicates that preserving a network of small forest patches may be of great conservation value to herpetofauna in the Sarapiqui region.

BENNETT, BRADLEY C.^* and ALARCON, ROCIO, Dept. Biological Sciences, Florida International University, bennett@fiu.edu, Effects of Indigenous Forest Management on Forest Composition in Amazonian Ecuador.
The lowland forests of eastern Ecuador support five distinct indigenous groups. The two largest groups, the Shuar and Quichua, number more than 100,000 and have occupied the region since Spanish occupation in the 1500s. When clearing fields, or chacras, both groups leave a large number of species. The Shuar, for example protect 155 species, including nearly 100 tree species. Species are allowed to persist in fields for a variety of reasons. Some are left because they are difficult to cut such as Minquartia guianensis (Olacaceae). The large tree also is valued as a source of a potent anthelmintic as well as source of posts for house construction. Many palms, including Astrocaryum chambira, Iriartea deltoidea, and Mauritia flexuosa (Arecaceae) are protected because of the diversity of products that they supply including edible fruits, fiber, construction material, and roof thatch. The Shuar often leave large members of the Malvaceae, such as Ceiba insignis and C. pentandra because the trees are believed to be the home of their ancestor's spirits. The Quichua will not cut Grias peruviana (Lecythidaceae) because they consider it to be the food of sacha huarmi, a female forest spirit. They protect Protium spp. (Burseraceae) so they can utilize resin from the trees to glaze pottery. Archaeological evidence suggests that many of these species also were protected by Pre-Colombian peoples who occupied the region. The current abundance and distribution of protected species in old growth forests probably reflects the cumulative effects of management strategies during the previous millennium. Many researchers have speculated that the abundance of Iriartea deltoidea in upland forests and Mauritia flexuosa in swamp forests is a result of past human activities. In this presentation, we discuss, Quichua and Shuar use of forest resources and how it relates to forest compensation in the region.

BENÍTEZ-MALVIDO, JULIETA^*, CIECO, UNAM, Antigua Carretera a Pátzcuaro No.8701, Ex-Hacienda de San José de la Huerta, jbenitez@oikos.unam.mx, Short vs. long term seedling performance and herbivory in Amazonia.
Deforestation in the tropics has led to management strategies that include planting of tree seedlings in order to expedite the process of regrowth. Studies that follow the fate of planted seedlings typically last for less than 5 years, making it difficult to assess whether a species is actually a suitable candidate for use in forest rehabilitation projects. I studied survival, growth in height and herbivory on three native seedling species (Chrysophyllum pomiferum, Micropholis venulosa, and Pouteria caimito), transplanted into primary and secondary forests in Central Amazonia. Performance was evaluated in the short-term at two monthly intervals from 1992-1993. Thereafter, performance and herbivory were evaluated in the long-term every two years to 2001. Results showed that initial trends in growth, mortality and herbivory changed drastically over the course of the study for all species. I showed that species co-occurring as adults in the natural forest differ in their seedling success in different rainforest habitats. Morphological characteristics and herbivory at early-stages of development might not correspond to species habitat preferences and biotic damage at older-stages. Initial responses cannot be always used to suggest species for rehabilitation.

BERKOV, AMY^* and CENTENO CHECALLA, PEDRO, City College of New York, Convent Avenue @ 138 Street, Dept. Biology, Marshak J526, berkov@sci.ccny.cuny.edu, Are Widespread Amazonian Insect Species Actually Species Complexes?
Assumptions about the host specificity of tropical insects are often incorporated into estimates of global species richness and used to generate estimates of extinction rates. Assessments of specificity used in these calculations are generally either guesses, or extrapolations from datasets of insects collected from plants using mass-sampling techniques. Sampled insects are sorted to morphospecies, and specificity is expressed in indices of similarity or effective specialization. These methods are prone to error if the morphospecies assignments do not correspond with recognized species. Other confounding factors arise if host association changes throughout the geographic range of an insect. Rearing data indicate that the Brazil nut family (Lecythidaceae) is associated with well-defined guilds of wood-boring cerambycid and curculionid beetles. A yearlong (1995-1996) rearing project in central French Guiana investigated the host, seasonal, and stratum specificity of the beetles, and a second rearing project is currently in progress in SE Peru. One objective is to determine whether host associations are stable in disjunct regions of Amazonia. Thus far it appears that of the wood-boring beetle species consistently reared in French Guiana, 32-50% are associated with the same host plant family in Peru. A second objective is to determine whether beetles that appear to belong to the same species, and are associated with the same host in disjunct regions, are indeed members of the same species. Sequence data have shown that sympatric cerambycid beetles in the genus Palame include multiple genetically distinct groups. These groups sometimes, but by no means always, correspond with changes in ecological niche. The study has important implications for conservation because, should tropical species frequently prove to be complexes of cryptic species, the presence of specialized ecological requirements will be masked by the generalized habits of the composite species.

BERKOV, AMY^* and PURZYCKI, KEN^*, CCNY Dept. Biology, Marshak J526, Convent Avenue @ 138 Street, berkov@sci.ccny.cuny.edu, Volatile Components of the Cannonball Fruit, Couroupita guianensis (Lecythidaceae).
Due to their tropical distribution and large stature, few members of the Brazil nut family (Lecythidaceae) are grown in cultivation. The cannonball tree, Couroupita guianensis Aublet, is a widely cultivated exception to the rule. The showy cauliflorous flowers are appreciated for their rosy floral and spicy scent, while the large spherical fruits enjoy a lesser reputation as foul-smelling and, when the ripe fruits fall from the tree, potentially hazardous. When a fruit falls, the thin woody pericarp cracks open and exposes the fetid pulp. When the pulp is exposed to air it turns bluish-green, and chemical analyses have documented the presence of the blue dye indigo and related indole alkaloids. We sampled headspace aromas from a cultivated cannonball fruit because we hypothesized that N-methylpyrrole, a potentially mutagenic compound detected in headspace analyses of Lecythidaceae wood, might be formed during the synthesis of indigo or another indole alkaloid. We also hypothesized that sulfur compounds, abundant in some Lecythidaceae wood analyses, would contribute to the persistent and unmistakable odor of the cannonball fruit. Although N-methylpyrrole was not detected, the fruit produced sulfur compounds in abundance. Detailed observations of seed dispersers have not been made for C. guianensis, but peccaries have been observed consuming the pulp, and seeds apparently pass through mammalian digestive systems unscathed. We hypothesize that sulfur compounds in Lecythidaceae fruits may attract mammalian seed dispersers.

BOHLMAN, STEPHANIE A.^* and GROTEFENDT, RICHARD, Smithsonian Tropical Research Institute, Unit 0948, steph@rad.ess.washington.edu, Sun-exposed crown area and large tree growth on Barro Colorado Island, Panama.
The empirical data on the relationship between light, competition and growth in tropical forests have been derived entirely from small trees and saplings. The highest rates of photosynthesis and greatest biomass in the forest come from upper canopy trees, yet we are almost entirely ignorant of the impact of light on growth of large trees. Large trees receive variable amounts of light based on their sun-exposed crown area and lateral shading, which is determined by neighborhood crown competition. For the first time, we quantified the relationship between sun-exposed crown area, light availability, neighborhood competition and tree growth of large trees in a tropical forest by developing a canopy map for 8-ha of the forest dynamics plot on Barro Colorado Island, Panama. We used stereophotos to determine the exact spatial locations of all sun-exposed crowns and linked the crowns to the plot stem data thus determining species identity and 20-year growth rates of the sun-exposed trees. Basal area (BA) accounts for much of the variability in sun-exposed crown area (ECA) for all tree sizes, but considerably less when only trees greater than 80 cm dbh are considered. ECA predicts basal area increment (BAI) considerably better than BA. For the same BA, gap species have a higher ECA than shade trees. Despite having different ECA per BA, gap and shade trees did no differ the relationship between ECA and BAI, suggesting that differences of large gap and shade trees occurs through allometry rather than differing responses to light. Correlations between ECA and BAI for individual species was highly variable, but were higher than between BA and BAI for all species.

BONGERS, FRANS^*, POORTER, LOURENS, HAWTHORNE, WILLIAM, KOUAMÉ, FRANCOIS and JONGKIND, CAREL, Centre for Ecosystem Studies, Wageningen University, P.O. Box 6700, frans.bongers@wur.nl, Biodiversity of West African forests.
The Upper Guinean forests are hotspots of biodiversity. We present a biodiversity atlas with accounts on deforestation, forest classification, and biodiversity hotspot analyses. Detailed species accounts for 300 rare and endemic species and 60 large tree species are included, as well as a checklist of forest plants in Upper Guinea. Furthermore we have developed a field guide for all (ca 2000) woody forest species in the area, with keys based on (mainly) vegetative characters, line drawings for all species and ca 1000 color photographs. These books may help in designing improved forest management.

BRAVO, SUSANA^*, Laboratorio de Ecología Funcional, Facultad de Ciencias Exactas y Naturales, Pab.II Ciudad Universitaria, sbravo@bg.fcen.uba.ar, Loss of genetic diversity in tropical trees: effects of seed disperser behavior.
Seed dispersers may favor gene flow, reduce endogamy and promote genetic diversity within plant populations. However, depending on the food choice by the disperser and on the pattern of seed distribution that it generates (e.g. clumped), the disperser activities could result in a decrease of genetic diversity, instead of its increases. A high level of clumping characterizes the seed dispersal pattern produced by howler monkeys (Alouatta spp). Black howlers (Alouatta caraya), in particular, are the most abundant arboreal frugivore in flooded forests along the Parana River from northern Argentina. This important seed disperser mammal tends to use seeds of Ocotea diospyrifolia infested by Heilipus spp. larva in the study site. The larva consumes the seed endosperm and the embryo and consequently damages the seeds if black howlers do not consume them. The passage through the black howler digestive tract eliminates the larvae. Trees with a large percentage of infested fruits exhibit a slow rate of germination, however if the seeds passes through the digestive tract of black howlers, its germination rates tend to be higher and similar to the germination rates of seeds from trees with a low proportion of infested seeds. Black howlers are the main dispersers of O. diospyrifolia in the study site; 90 % of these tree species saplings are established in black howler's latrines. Black howler food choice facilitates the reproduction of the slow germination phenotypes (the trees heavily infested by the larvae), perhaps promoting the loss of genetic diversity in O. diospyrifolia populations.

BRIGHTSMITH, DONALD J.^*, Duke University Department of Biology, Box 90338, djb4@duke.edu, Parrots' dirty eating: the effects of weather and season on clay lick use in Tambopata, Peru.
Soil consumption, or geophagy, among parrots and other birds is a conspicuous phenomenon in many rainforest areas of the Western Amazon Basin. However the ecology of this phenomenon is still poorly understood. In southeastern Peru birds gather daily by the hundreds to eat sodium-rich clay soils from river edge "clay licks." The current study uses regression analyses of 607 mornings of observations to evaluate the influence of season and weather on total lick use by birds at a site along the Tambopata River in the Peruvian Amazon. Parrots dominated the lick in both total number (99.7% of 307,740 registrations) and total species (14 of 20). The model developed here accounts for approximately 40% of the variation in daily lick use. Lick use was lower on rainy and foggy mornings and higher on sunny mornings. Lick use between months differed by up to an order of magnitude and was highest in September and lowest in May. Additional data from the site show that the seasonal changes in lick use may be driven by a combination of parrot "migrations" and the dietary needs of young chicks.

BROWN, STEVEN^*, KUHN, DAVID, MOTAMAYOR, JUAN CARLOS, LOPES, UILSON and SCHNELL, RAYMOND, c/o USDA-ARS, 13601 Old Cutler Rd., miajb@ars-grin.gov, Resistance gene mapping for witches′ broom disease in Theobroma cacao L. in an F₂ population.
A genetic linkage map was created with 146 trees of cacao (T. cacao L.) from an F₂ population of a cross between the clones, Sca6 and ICS1. Simple sequence repeat (SSR) markers were used principally for this map with a total of 170 SSR markers. Twelve markers developed from candidate genes (Resistance Gene Homologues (RGH) and stress related, or WRKY genes) were also used, for a total of 182 markers. Joinmap® software from Plant Breeding International was used to create the map, and 10 linkage groups were clearly obtained, corresponding to the 10 chromosomes of cacao and to the 10 linkage groups in the high-density cacao map of Risterucci et al. (2000). The map covered approximately 671.9 centimorgans, as opposed to 885.4 in the high-density map. Approximately 27% of the markers showed serious segregation distortion, however, and this distortion tended to map towards six areas of the genome. Two QTL (quantitative trait loci) for resistance were found, one being strong and highly repeatable, and one for trunk diameter, which was only 10.2 cM away from the stronger gene for witches′ broom resistance. The use of cofactors indicated these two genes, though rather closely linked, to be independent loci and not one true locus with penetrance in two underlying, related traits. One of the RGH, RGH11, flanked the second QTL for witches′ broom resistance, and another, RGH2, flanked the QTL for trunk diameter, and was therefore also relatively close to the other QTL for witches′ broom resistance (24.6 cM away). This is the only F₂ cacao population mapped to date, and will constitute a very useful cornerstone population for future cacao research, as well. Identifying the location of this gene will enable breeders to move resistance across geographical barriers more rapidly.′

BRUNA, EMILIO M.^*, VASCONCELOS, HERALDO L. and HEREDIA, SYLVIA, University of Florida, Wildlife Ecology and Conservation, PO Box 110430, BrunaE@wec.ufl.edu, The effect of habitat fragmentation on communities of mutualists: amazonian ants and their host plants.

The consequences of fragmentation for communities of mutualist partners are for the most part unknown; moreover, most studies addressing this issue have been conducted on plant-pollinator communities. We evaluated how the experimental fragmentation of lowland Amazonian rain forest influenced a community of ant-plant mutualists. We inventoried a total of 1057 myrmecophytes in four fragments and four continuous forest sites; the twelve plant species recorded were occupied by 33 ant morphospecies, of which 11 were obligate plant inhabitants. Neither plant species richness, ant species richness, or total ant-plant density was significantly lower in forest fragments. However, eight of the plant species, including three of the four most common, had higher mean densities in continuous forest than fragments. Of these four species, only one (Cordia nodosa) had significantly different colonization rates between habitat types, with higher colonization rates of plants in fragments. This may be because the Azteca species is increases in abundance in forest isolates. Although our results suggest that communities of ant-plant mutualists are likely to persist in fragmented tropical landscapes in the short term, most species are rare and populations sizes in fragments are extremely low. Environmental and demographic stochasticity could therefore limit long-term population viability. We suggest future studies focus on evaluating how fragmentation has altered herbivore pressure and the dispersal of ants and plants to fragments, since the interaction of these factors is likely to have the greatest impact on long-term patterns of population persistence.

BUCCI, SANDRA J.^*, GOLDSTEIN, GUILLERMO H., VILLALOBOS, RANDOL, SCHOLZ, FABIAN G., MEINZER, FREDERICK C., FRANCO, AUGUSTO C., CAMPANELLO, PAULA I. and BUSTAMANTE, MERCEDES, Department of Biology University of Miami, s.bucci@miami.edu, Nutrient availability constraints the hydraulic architecture and water relations of savanna trees.
The investment in plant parts that acquire the limiting nutrient is usually favored at the expense of allocation to plant parts that have a large requirement for the limiting resource. Plants will allocate relatively more biomass to their roots to enhance nutrient uptake if the soils are, for example, N limited. If N limitations are relief, the pattern of biomass allocation may change favoring the expansion of the leaf surface area, to enhance CO₂ capture, at the expenses of underground plant parts. The objective of this study was to remove some of the nutrient limitations of Brazilian savanna (Cerrado) soils by long term fertilizations (six years of continuous fertilization with N, P and N+P) and to explore the consequences that potential changes in the pattern of carbon allocation may have on the hydraulic architecture and water relations of five dominant tree species. Addition of N and N+P increased the total number of leaves per tree, total surface area per tree, and the leaf area per unit of sapwood area, which is a morphological index of water transport efficiency. On the other hand, leaf size decreased significantly in all species with P fertilizations. Daily sap flow per individuals tended to be higher with N and N+P additions despite a substantial decrease in daily transpiration rates. The largest physiological effect of fertilizations with N and N+P was a large decrease in midday leaf water potential (e.g. 1 MPa). Apparent soil to leaf hydraulic conductance at midday tended to be lower in the fertilized plots across all species. Overall, the results suggest that fertilization with N, resulting in an increase in the total leaf surface area per tree, is not compensated by an increase in the hydraulic capacity of the water conductive tissues.

BUSCHBACHER, ROBERT J.^*, JACOBSON, SUSAN, KAINER, KAREN, PUTZ, FRANCIS, SCHMINK, MARIANNE, STEPP, RICK and ZARIN, DANIEL, PO Box 110760, University of Florida, rbusch@ufl.edu, Multidisciplinary Research and Education on Neotropical Working Forests.
The University of Florida, with support from the NSF Integrated Graduate Education Research and Traineeship Program, has launched a new multi-disciplinary program of doctoral study called Working Forests in the Tropics. The program brings together students and faculty from a broad range of academic units across campus to collectively address a common research topic: what working forests can contribute to tropical conservation and development. Research is conducted in partnership with collaborating universities, NGOs and government agencies in four neotropical regions: lowland Bolivia; Acre, Brazil; eastern Amazonia, Brazil; and the Maya Forest (Mexico, Belize, Guatemala). Our research framework addresses the ecological and socio-economic impacts of a range of working forest uses, and emphasizes that societal and biophysical contexts shape choices about working forest options, the impacts of which contribute to (or detract from) progress toward conservation and development goals. Six research themes are derived from this framework: Capacity Building, Cultural Persistence and Change, Ecological Dynamics, Forest Management Systems, Macro-Economics and Infrastructure Development, Policy and Governance. Recognizing the breadth and complexity of this topic, our approach is to involve students and faculty from multiple disciplines -- the first 15 student fellows in the program represent 7 different academic departments. The Working Forests in the Tropics curriculum supplements students^, training in their chosen disciplines with cross-disciplinary requirements, integrative coursework, and practicum learning opportunities. Applications are being accepted for the 3rd cohort of Ph.D. fellowships in February 2005.

CACCIA, FERNANDO^* and DIRZO, RODOLFO, Av. San Martín 4453, fcaccia@mail.agro.uba.ar, Density-dependent seed removal and recruitment in two Neotropical Legumes with contasting dispersal modes.
To investigate the relative importance of seed density on recruitment through its effect on seed removal by rodents, we carried out two experiments in the low decidious rainforest of Chamela (México, Jalisco). In the first experiment treatments consisted of a factorial combination of species identity ( Leucaena lanceolata or Pithecellobium dulce) and seed density (4 or 50 seeds/Petri dish). After 5 days, there was a significant interaction between seed identity and seed density on seed removal rates. Average seed removal for L. lanceolata was enhanced by seed density (63 vs 30%) whereas there was a negative response for P. dulce removal rates to seed density (30 vs 50% for the high and low seed density treatments respectively). To specifically study the effects of species identity ( L. lanceolata or P. dulce ) and seed density (4 or 50 seeds) on recruitment patterns we sowed seeds of each species directly on the ground following the same treatments described above. We covered each sown seed bacth with a wire mesh exclosure to prevent rodent access to the seeds. After 5 days, emergence was significantly higher for P. dulce and for the low seed density treatment. After 35 days, seed sown density had a negative and highly significant effect on recruitment for both species (5 vs 21% for the high and low seed density sown respectively) as result of density-dependent mortality, presumably due to biotic agents. Our results strongly suggest that for both species post-dispersal seed removal by rodents, even at relatively high rates, had no negative effects on recruitment due to a strong density-dependent mortality during the early postemergence stage. In addition, our results suggest that seed dispersal by birds away from parent plants does not enhance recruitment for P. dulce and that high natural seedfall under L. lanceolata canopy does not satiate rodents. á

CAMPANELLO, PAULA^*, GATTI, M. GENOVEVA^* and GOLDSTEIN, GUILLERMO^*, Lab. de Ecología Funcional, Dep. Ecologia, Genetica y Evolucion, FCEyN, Univ. de Buenos Aires, Cdad Universitaria, Pab II 4piso, pcampa@bg.fcen.uba.ar, Impact of life history traits on physiological attributes of canopy species growing under different light regimes.
The ability of plants to modify the internal allocation of carbon and resources under different light environments is an important factor determining growth and survival in tropical forests where large microclimatic changes occur as a result of canopy gap formation. The way morphological and physiological attributes change and correlate across a range of potential environments could lead to a better interpretation of plastic responses in relation to life history traits. The study of the relationships between hydraulic architecture and carbon uptake may improve our understanding of plasticity responses, as long as photosynthetic capacity represents a measure of the maximum demand for water in the leaves and has proved to correlate with water transport capacity across species and habitats. In this context, the effects of different light environments on hydraulic architecture and photosynthetic capacity were studied in saplings of seven canopy species of the Atlantic Forest in Northern Argentina. Measurements of hydraulic conductivity, leaf to sapwood area ratio, xylem vulnerability to cavitation, wood density, maximum photosynthetic rate, carbon stable isotope composition of leaves, specific leaf area, and growth rate were obtained in saplings acclimated to different light environments. The response for these attributes varied among the species. Their ability to coordinate morphological and physiological changes, and whether plastic responses enhanced growth rate, were fundamental questions addressed in this study.

CAMPBELL, RICHARD J.^*, 11935 Old Cutler Rd., rcampbell@fairchildgarden.org, Diversity and domestication of avocados in the Caribbean.
The avocado is an important fruit crop for subsistence farmers, small and large producers throughout the tropics. Originating in Tropical America, the major edible avocados are classified into three dominant horticultural races: Mexican, Guatemalan and West Indian. Throughout lowland Tropical America, the West Indian and West Indian/Guatemalan hybrids dominate due to their superior adaptation to the climatic and edaphic conditions. Several international projects have been instituted to safeguard the genetic resources of avocado in Tropical America, but these efforts have focused primarily on the Mexican and Guatemalan races. Few resources have been devoted to the identification, collection and maintenance of West Indian avocado genetic resources. West Indian avocado genetic resources hold promise for the improvement of disease resistance, fruit quality and productivity of avocado throughout Tropical America and the world. The present work outlines the current effort by FTBG into the collection, conservation and characterization of West Indian avocado genetic resources of lowland Tropcial America.

 CAO, KUN-FANG^*, ZHANG, JIAO-LIN and ZHU, JUN-JIE, 88 Xuefu Road, caokf@xtbg.ac.cn0, Seasonal variation of photosynthetic physiology in woody plants in a valley savanna in southwestern China.
We monitored the seasonal variation in photosynthesis, chlorophyll fluorescence, spectral reflectance and water potentials in six woody species in a savanna on the valley slopes along the Yuanjiang River in southwestern China, during 2003 and 2004. These species include an evergreen species, Cyclobalanopsis helferuana, two deciduous species Buchanania latifolia and Symplocos racemosa, and three semi-deciduous species Terminthia paniculata var. intermedia, Wendlandia tinctoria, and Woodfordia fruticosa. Surprisingly, the water potentials at predawn and noon of the six species in either seasons were quite high, ranging from −0.036 to −0.47 Mpa among species. These species in the rainy season had quite high net photosynthetic rates (A), the morning mean values ranging from 9.2 to 18.8 umol m^-2 s^-1. Their photosynthetic rates were reduced by 37-82% in the dry season. With the pooled data from all species, the regression slope of A vs stomatal conductance for the dry season was significantly greater than that for the rainy season, indicating greater water use efficiency of the plants in the dry season. In the dry season, four of the six species suffered severer reversible photoinhibition, and their non-photochemical quenching rates accelerated. In the dry season, the spectral reflectance of the six species increased. There was significant negative correlation between chlorophyll content related reflectance index (Chl NDI) and the mean reflectance of photosynthetic active radiation (400-700nm), whereas, there was no correlation between Chl NDI and relative leaf water content. These suggested that the increase of spectral reflectance in the dry season was mainly related to the decrease of leaf chlorophyll content. Our results revealed the seasonal drought leaded to significantly suppression of photosynthesis in all species, and acceleration of reversible photoinhibition in four of the six species. The six species had somewhat different behavior during the dry season.

CARABALLO-ORTIZ, MARCOS A.^* and SANTIAGO-VALENTIN, EUGENIO, Departamento de Biología, Universidad de Puerto Rico-Río Piedras Apartado 23360, maco_pr@yahoo.com, Aspects on the pollination biology of Goetzea elegans (Solanaceae).
Many endangered plants suffer problems in their reproductive biology, and as a result their effective conservation can be affected. Goetzea elegans is an endemic Puerto Rican endangered tree. Their flowers are visited by vertebrates as invertebrates, including native and exotic species. This study compares pollination efficiency between an exotic (Apis mellifera) and a native (Coereba flaveola) pollinator in G. elegans. Preliminary data shows that both species are pollinators of G. elegans, but they differ in their pollination efficiency. This difference can be due different pollinators behavior when visiting flowers. C. flaveola visits more trees with less time visiting individual flowers, contrasting with A. mellifera, which visits fewer trees spending more time in each flower. Because G. elegans is mainly autoincompatible, effectivity differences in pollen transference can be considered an important factor in efforts for this species conservation.

CARNAVAL, ANA CAROLINA Q.^*, 1639 North Vine St, accarnav@uchicago.edu, Patterns of genetic diversity among breeding assemblages in a population of Brazilian ground dweller frogs.
I used mitochondrial DNA data from 718 bp of the cytochrome-b gene to investigate the distribution of genetic diversity among frog breeding assemblages in an Atlantic Forest remnant in the state of Pernambuco, NE Brazil. Thirty-six individuals of the litter frog Proceratophrys boiei were sampled from four different breeding sites. Two related questions were asked, addressing whether there is genetic structure across breeding assemblages, and how well a single assemblage depicts the overall spectrum of genetic diversity sampled in the forest fragment of interest. Fifteen haplotypes were found, differing by one to 22 mutational steps. AMOVA results indicate that individuals have been historically able to move among breeding sites, as the majority of local genetic variation is attributed to differences within breeding assemblages. Nearest-neighbor statistics nonetheless detected genetic differentiation of one breeding assemblage, in which private haplotypes occur in relatively high frequencies. Sampling 6-10 individuals from a single breeding site allowed me to capture 87-100% of the total genetic diversity in this area, providing reliable estimates of overall haplotype and nucleotide diversities. This shows that P. boiei can be used as a model organism to compare levels and patterns of genetic diversity among forest fragments even in instances where the number of sampled breeding sites differs among remnants. The latter was an issue of concern in population genetic studies in the seasonally wet Brazilian Atlantic Rainforest, where field work is frequently done through opportunistic visits to breeding sites during the rainy season, and where sampling effort often differs among localities. The remarkable amount of genetic variability and deep genetic differences found in this forest remnant mirrors other tropical frog studies and poses a warning to phylogeographic investigations based on a single or couple of individuals per locality.

CASTRO-ARELLANO, IVAN^* and LACHER, JR., THOMAS E., Dept. of Wildlife & Fisheries Sciences., Nagle Hall 210. 2258 TAMU, Texas A&M University, ivancastro@tamu.edu, Relevance of temporal niche dynamics for rodent community patterns at El Cielo Reserve, Mexico.
We investigated the activity patterns of small mammals, and their relevance for community structure, at two contrasting zones (Tropical Subdeciduous Forest and Cloud Forest) of El Cielo Biosphere Reserve in southwestern Tamaulipas. To determine these patterns we used Sherman live trap transects during summer months of three years (2000-2003). Sampling periods coincided with new moon nights. Traps were set by 1900 hr and were checked every 2 hr until 0700 hr. During the day we left them open to detect any diurnal activity. We detected a total of nine species and obtained adequate sample sizes for six. No single diurnal capture event was recorded and use of the crepuscular and night periods was uneven among the species with diverse degrees of overlap between species pairs. We used information on microhabitat and body masses to interpret these patterns and detected several cases of niche complementarity; eg., Liomys irroratus and Oryzomys couesi (two potential competitors due to highly similar body masses) shared microhabitats but differed sharply in their activity patterns. Overall, we demonstrate non-random structure in these communities thus calling for further testing to ascertain the mechanistic explanation responsible for these patterns. Even though study of time partitioning may aid in understanding the coexistence of species that occupy similar ecological niches, activity pattern research has not received much attention as other niche axes (food, microhabitat, etc.). We discuss the relevance of temporal niche dynamics for mammal community studies within the frame of evolutionary ecology and the new field of chronoecology.

CATENAZZI, ALESSANDRO^*, DONNELLY, MAUREEN and CARRILLO, JORGE, OE167, Department of Biological Sciences, Florida International University, acaten01@fiu.edu, Winter thermal ecology of the intertidal lizard Microlophus peruvianus in Southern Peru.
Among ectothermic vertebrates, lizards display the widest diversity of thermoregulatory behaviors, and therefore constitute a choice model to test hypotheses on thermal ecology. Microlophus peruvianus is a tropidurid lizard with a wide distribution in western South America, extending from southern Ecuador to northern Chile (i.e., more than 3,000 km). The thermal environment varies along a north to south gradient, due to the increasing levels of cloud cover associated with the persistent upwelling of the Peru-Chile marine current. We tested the hypothesis that lizards should be more eurythermal in areas where temperatures are spatially homogeneous, such as closed forests or areas with persistent cloud cover, than in open areas, such as deserts. We compared thermal data collected by Huey (1974) at the Illescas Peninsula in northern Peru (5°S) with data we collected at the Paracas Peninsula in southern Peru (14°S). Mean field temperature of active field lizards in Paracas is 33.0°C +/-3.0°C (range 24.2-37.8°C), significantly lower than mean field temperature at the Illescas site (36.3 +/-0.26°C, range 32.3-39.0°C). Mean body temperature of Paracas lizards in a photothermal gradient is 35.6°C +/- 1.7°C, matching values recorded by Huey in northern Peru. Lizards in Paracas showed a strong unimodal surface activity pattern, with most activity concentrated around midday. Juveniles tended to be active earlier in the morning at suboptimal temperatures. We discuss thermoregulation strategies and a higher cost of thermoregulation for lizards in Paracas.

CAUSEY, BILLY^*, Florida Keys National Marine Sanctuary, PO Box 500368, Billy.Causey@noaa.gov, Linking Coral Bleaching and Secondary Impacts to Climate Change in the Florida Keys.
Coral reefs in the Florida Keys have responded to climate change in a variety of ways for the past two and a half decades. Since the early 1980s coral bleaching has intensified and expanded geographically throughout the Keys, ranging through a variety of coral reef communities. Lessons learned over the past two and a half decades have made it possible for coral reef managers to not only predict the coral bleaching events, but implement management actions prior to the stressful periods. This paper will give a chronological sequence of coral bleaching events in the Florida Keys, as they relate to regional and global events. Lessons learned from the response of coral reefs to climate change will be documented through photographs and in situ observations. Secondary impacts such as increased coral diseases resulting from the stress of coral bleaching will be spatially demonstrated and discussed in the paper. As sea temperatures have steadily increased, so has the incidence of coral bleaching and coral diseases. As coral reef communities, first in the Wider Caribbean and later in the west Pacific, reached specific thresholds in their tolerance and exposure to thermal stress, the geographical spread of coral bleaching and later coral diseases has been noted by resource managers and coral reef scientists. These observations will be discussed in the paper.

CAVALERI, MOLLY A.^*, RYAN, MIKE G., CLARK, DEBORAH A., CLARK, DAVID B., OBERBAUER, STEVEN F., ORDONEZ, HARLYN and OLIVAS, PAULO, 1112 Columbine Ct. #7, cavaleri@cnr.colostate.edu, Modeling carbon efflux in a wet tropical rain forest using scaled up chamber respiration measurements and eddy covariance data.
Tropical rain forests (TRFs) contribute about one third of the planet's gross primary production, yet little is known about the carbon balance of these systems. Recent studies disagree about whether TRFs act as carbon sources or sinks. Because respiratory losses determine whether a forest is a source or sink, carbon loss in a primary TRF was examined by extrapolating chamber respiration measurements of foliage and wood to the landscape. A mobile walk-up tower was used to access vertical transects throughout the study site. Preliminary results show relationships between respiration and canopy structural variables. Foliar respiration increased with height for trees and vines, while palm respiration decreased with height above 12 m. Foliar respiration increased with increasing foliar N, and there was a similar respiration:N ratio for all functional groups. Wood respiration of boles measured in the understory increased with increasing bole diameter, while respiration of branches higher in the canopy increased as a function of height, regardless of diameter. These data, along with published soil respiration data will be summarized and compared to three years of nighttime eddy flux net ecosystem exchange (NEE) data from the same location. I predict that the nighttime NEE flux will be lower than ecosystem respiration extrapolated from chamber measurements likely because nighttime NEE measurements do not meet the assumptions for valid flux measurements. If so, studies that report a large sink for TRFs based on eddy flux measurements may be in error.

CAVENDER-BARES, JEANNINE M.^*, Dept of Ecology and Evolutionary Biology, 1987 Upper Buford Circle, cavender@umn.edu, Convergence and coexistence of Florida oaks.
High species diversity is found in north central Florida, where the climate is favorable for both southern subtropical and northern temperate species. In particular, an unusually high number of oak species co-occur (17 species), inviting explanation. Oak species occur in distinct local communities that vary with respect to soil moisture and nutrients, as well as fire regime. Physiological traits of species, measured both in the field and in a common garden, show convergence in plant function across lineages. Thus, distantly related oak species occur together within communities more often than expected by chance because of similarities in phenotypic specialization for the same habitats. For example, from each of the three major lineages in the region (red oaks, white oaks and live oaks), there is a short, shrubby species that resprouts readily from underground rhizomes, making it well-suited to the high intensity fires of the Florida scrub, and a tall species with high hydraulic conductance and fast growth, well-suited to the fertile, mesic hammocks of the region. Traits that are conserved within phylogenetic lineages, such as phenology and seed maturation time, may reduce competition between distantly related, co-occurring oaks. The interspersion of different lineages of oaks may also reduce density dependent mortality if disease resistance is conserved. Hence, evolutionarily labile traits that allow specialization for particular habitats, give rise to phylogenetically overdispersed communities that permit species packing and contribute to the maintenance of high oak diversity in the region.

CERVANTES-MARTINEZ, CUAUHTEMOC^* and BROWN, STEVEN, 13601 Old Cutler Road, ccervantes@saa.ars.usda.gov, A haplotypic approach for QTL mapping in outbred species.
The integration of quantitative trait loci (QTL) analysis into breeding strategies rather than seen as separated processes, has been proposed to increase the power and accuracy of QTL detection and to allow the two activities to be joined. The main objective of this research was to develop a specific scheme for mapping quantitative trait loci (QTL) in actual breeding F1 populations of outbred plant species with a high degree of accuracy. The method was applied to computer simulated data sets, corresponding to five F1 populations of 100 individuals each obtained from the crosses of a common founder with several other founders. We are currently using this scheme with cocoa (Theobroma cacao L.) crosses, using selected clones resistant to specific diseases to widen the genetic base of disease resistance. The results indicate that the position and effect of QTLs in the common founder, that explain each at least 14% of the phenotypic variance, can be estimated with good precision and accuracy.

CHACOFF, NATACHA^* and AIZEN, MARCELO, Laboratorio de Investigaciones Ecológicas de las Yungas, Universidad Nacional de Tucumán, CC 34, natachachacoff@arnet.com.ar, Edge effects on pollinators, pollination and fruit production in grapefruit plantations bordering Argentinean Yungas forest.
The pollination of flowering plants represents a critical process for both natural and agricultural ecosystems that could be greatly affected by the destruction, degradation, and fragmentation of natural habitats. We estimated abundance and diversity of pollinators, as well as pollination and reproductive levels in pigmented grapefruit (Citrus paradisi Macf.) plantations bordering subtropical mountain forest in NW Argentina. These variables were assessed at increasing distances from the forest edge (0, 10, 100, 500, and 1000 m) in four plantations and over three consecutive years. The total visit frequency, visits by honeybees, visits by other pollinators, and pollinator species richness, all decreased linearly as distance to the forest edge increased. The relative visitation by pollinators other than honeybees declined from 14 to 2% from the forest edge to 1000 m. Pollen loads in the stigma and pollen tubes in the style also decreased monotonically as distance to the forest increased, but no edge effect was found on fruit and seed set. Despite self-compatibility, the studied grapefruit varieties require insect pollination for high yields: open-pollinated flowers set ca. six times more fruits than either emasculated or bagged flowers. Also, hand-pollinated flowers set nearly twice as many fruit as open-pollinated flowers. This study provides empirical evidence for considering remnants of natural habitats as a source of both native and alien pollinators for agriculture. Although, in general Citrus have been considered as low pollinator-dependent crops, we found that at least in these grapefruit varieties insects play an important role for fruit production. However, in our system a clear negative edge effect on pollinator abundance and pollination were not strong enough to cause an expected decline in fruit set despite evidence of pollen limitation.

CHAPOTIN, SAHARAH MOON^* and HOLBROOK, N. MICHELE, Biological Laboratories, 16 Divinity Ave., chapotin@fas.harvard.edu, Understanding the role of high stem water content in baobab trees from a physiological and a biomechanical perspective.

The large quantity of water maintained in the wood of baobab trees (Adansonia spp.) is widely thought to represent an adaptation to the arid climate in which they grow. In order to examine the role that high stem water content and large stem volume play in the biology of baobab trees in Madagascar, we assessed whole tree water use on a seasonal basis and explored biomechanical considerations involving their large size and low-density wood. The relative contributions of stem water and soil water were measured using sap flow probes and isotope tracers, and by determining leaf level water loss, stomatal conductance and stem water content. During the leaf flushing period, sapflow rates from the roots to the tree were zero despite measured sapflow from the trunk to the branches and a decrease in stem water content. The onset of stomatal opening, however, was delayed until after significant rain had fallen and sap flow rates at the base of the trunk reached high rates. The use of stem water storage was mainly limited to supporting new growth and cuticular transpiration while the high levels of water use associated with photosynthetic activity were dependent on high soil water availability. The structural properties, caloric content, cellular content, and extent of living tissue in the stem wood were also measured to determine whether the large diameter and water content of baobab stems could be due to biomechanical constraints rather than water storage capacity. Although baobab wood has a construction cost several times lower than the wood of more typical trees, the resulting low modulus of elasticity requires baobab stems to have a much greater diameter. Therefore, in addition to water storage, their distinctive shape and water content might reflect biomechanical tradeoffs associated with building tall forest trees out of weak, but inexpensive, wood.

CHAZDON, ROBIN L.^*, REDONDO BRENES, ALVARO and VILCHEZ ALVARADO, BRAULIO, Unit 3043, Department of Ecology & Evolutionary Biology, University of Connecticut, chazdon@uconn.edu, Tree dynamics over six years in wet tropical second-growth forests.
Dynamics of trees in young, second-growth tropical forests reflect species-specific and stand-specific changes in recruitment rates, mortality rates, and size distributions. We monitored growth, mortality, and recruitment annually for six years for all trees 5 cm DBH or greater in four 1-ha plots in second-growth, lowland rain forests in northeastern Costa Rica. Stands initially ranged in age from 12 to 25 years since abandonment of cattle pastures. Annual rates of tree mortality and recruitment into the 5 cm size class varied significantly among years, whereas recruitment into the 10 cm size class did not vary significantly among years. Tree mortality was highest during the 1997-1998 ENSO period; on average, 5.6, 3.5, and 1.4 percent of trees died in the small, intermediate, and large size classes, respectively. Mortality rates during the ENSO year were 1.9 times higher for trees 10 cm DBH or greater compared to non-ENSO years. Annual mortality rates decreased significantly with increasing dry season rainfall, but not with total annual rainfall during the census periods. In younger stands, abundance decreased in the small size class (5-10 cm DBH) but increased dramatically in the large size class (more than 25 cm DBH). Common species changed dramatically in abundance over 6 years within plots, reflecting high mortality of early colonizing tree species and rapid rates of recruitment of shade-tolerant tree and canopy palm species. Mortality rates of trees 5-9.9 cm DBH were higher in younger stands than in older stands. Tree mortality in these young secondary forests is highly sensitive to dry season rainfall, even during non-ENSO years. Increased tree mortality during ENSO years is likely to accelerate forest dynamics and successional change in wet tropical second-growth forests.

CHOAT, BRENDAN^* and HOLBROOK, N MICHELLE, 3079 Bio Labs, 16 Divinity Av, bchoat@fas.harvard.edu, Variation in hydraulic traits of Cordia species occurring across a rainfall gradient.
We investigated intra- and inter- specific variation in hydraulic traits of Cordia occurring at three sites of contrasting water availability: a wet site (La Selva, Costa Rica: 4000 mm/y), an intermediate site (Barro Colorado Island, Panama: 2600 mm/y) and a dry site (Palo Verde, Costa Rica: 1500 mm/y). Trees of the genus Cordia are distributed throughout the neotropics; Cordia alliodora (Ruiz and Pav.) Oken has the widest distribution of the genus, occurring at wet and dry sites from 25° N to 25° S. Hydraulic architecture and vulnerability to drought-induced embolism were compared in (a) individuals of C. alliodora occurring at all three sites and (b) in other species of Cordia which were restricted to one of the sites. In general, species growing at the drier sites were less vulnerable to drought-induced embolism than those growing at the wetter sites. Species occurring at the wetter sites had a lower ratio of leaf area to sapwood area (Huber value, HV), but higher sapwood specific conductivity (K_s). Leaf specific conductivity (K_L) was lowest for species occurring at the wettest site. Intra-specific variation was also evident in populations of C. alliodora at different sites, and was similar to the inter-specific trends observed. Individuals of C. alliodora at the dry site were less vulnerable to embolism than individuals at wetter sites, and HV was greatest for C. alliodora occurring at the driest site. However, in contrast to inter-specific trends, K_s and K_L were higher at the driest site. Further study is required to determine whether the variation observed in hydraulic traits of C. alliodora is a result of phenotypic plasticity or genetic differences between populations at different sites.

CHOO, JOHANNA^* and STILES, EDMUND, Department of Biology, Rutgers University, Piscataway, NJ, johchoo@rci.rutgers.edu, Frugivorous Bird Communities in a Neotropical and an Asian Paleotropical Site.

We present a comparison of frugivorous birds and fleshy-fruited plants in two lowland rainforest sites with comparable climatic conditions. Studies were conducted in the asian paleotropics of Sarawak (Mulu National Park), and the neotropics of Peru (Paucarillo Reserve, Amazonia). Field surveys assessed understory avian communities through mist-netting and canopy avian communities through observations at fruiting trees. Fruit diversity and production was determined through phenology surverys and fruit crop size estimations. Fruiting plants were identified and ripe fruit samples were collected. Our neotropical study site had a higher diversity of fruits and birds compared to our paleotropical site. Mulu had 40% fewer fruiting Families than Paucarillo, and both locations had >20 fruiting Familes in common. In both sites, Moraceae was an important fruiting Family with many species, but Ficus was the only genus for Moraceae in Mulu. Total avifaunal diversity was higher in Paucarillo (34% more species than Mulu), but both sites had similar diversity of frugivorous species. Our study of both canopy and understory birds showed that birds in Mulu were more flexible in their foraging behavior, with some frugivorous species able to forage across the vertical forest strata. In contrast for Paucarillo, understory birds generally did not forage in the canopy, and canopy birds were generally not caught in mist-nets. This finding suggests that for the asian paleotropical site, the classification of birds as understory or canopy frugivores could be misleading.

CHUST, GUILLEM^*, CHAVE, JEROME, CONDIT, RICHARD, AGUILAR, SALOMON, LAO, SUZANNE and PEREZ, ROLANDO, Laboratoire Evolution et Diversité Biologique, UMR 5174 CNRS/UPS; UPS Toulouse III, batiment IVR3; 118, route de Narbonne, chust@cict.fr, Spatial modelling of tree beta diversity in Panama tropical forest.
A debate has recently developed on whether the regional distribution of tropical plant species should be determined by dispersal limitation or by environmental factors. The hypothesis that dispersal history provides the main explanation for variation in plant species composition is based on Hubbell's neutral theory, which predicts that floristic similarity among plots should decrease with increasing geographic distance because of spatially limited dispersal (Condit et al. 2002, Duivenvoorden et al. 2002). However, existing statistical methods for partitioning the variance of species composition suffer from technical deficiencies, and a comprehensive interpretation of observed patterns of tropical tree beta diversity is lacking. We propose a way to spatialize a measure of tree beta diversity at the scale of the Panama Canal Watershed. First, we clarify the extent to which environmental factors and geographical distance account for floristic composition in this watershed. Using this information we construct the best (i.e. the most parsimonious) predictive statistical model using permutation-based multiple regression on distance matrices. We carry out a partitioning analysis of species variation using canonical analysis. Second, we use the regression model computed on distance matrices to construct a 'similarity map' of the Panama Canal Watershed. The amount of variation shared between spatial and environmental variables is 15-21% and that of unexplained variation is 42-50%. We conclude that the distribution of Panamanian tree species is primarily consistent with the 'random walk' model as predicted by Hubbell's neutral theory, supplemented by an 'environmental segregation' process, in particular by climate. Our similarity map demonstrates the practical relevance of our study in conservation planning, for instance in defining complementary areas. This method should help guide the efficient allocation of the scarce resources available for protecting biodiversity, in remote areas with limited access.

CLARK, DAVID B.^* and CLARK, DEBORAH A., La Selva Biological Station, Puerto Viejo, Costa Rica, University of Missouri St. Louis, OTS, Interlink 341, P.O. Box 025635, dbclark@sloth.ots.ac.cr, Short-term dynamism and medium-term stability across an old-growth tropical rain forest landscape.
Tropical rain forest dynamics are typically studied on time scales of 5-50 years. Virtually nothing is known about the magnitude of annual fluctuations in key forest demographic parameters such as annual mortality and recruitment. Here we report on a unique dataset from 18 0.5 plots in an old-growth Tropical Wet Forest, where all trees >=10 cm diameter were measured annually over a 6-yr interval. The study site was the La Selva Biological Station, Costa Rica. Analyses based on the first and last census show a very stable system. Total deaths and total recruits over the 6 years were virtually identical (695 vs. 699). Mean stem density, mean stem diameter, and mean plot basal area all changed

CLARK, DEBORAH A.^*, CLARK, DAVID B. and OBERBAUER, STEVEN F., INTERLINK-341, POB 02-5635, daclark@sloth.ots.ac.cr, Climatic and edaphic impacts on litterfall within a tropical wet forest: a 6-yr study.
While it is now recognized that the responses of tropical rain forests to global atmospheric and climate changes could strongly affect atmospheric carbon dioxide accumulation, carbon cycling in these ecosystems is still poorly understood. In the tropical wet forest at La Selva, Costa Rica, a large team of researchers has been been collaborating since 1996 in long-term study (the CARBONO Project) of the forest carbon cycle. Fine litterfall is the largest component of aboveground production in this forest, accounting for 2-3 times more fixed carbon than in wood production. Litterfall has been quantified biweekly in the CARBONO plots, 18 0.5-ha plots sited using the La Selva GIS to sample the landscape's large edaphic gradients (highly weathered slopes to depositional terraces, 3-fold variation in soil P, K, Al) with an unbiased, replicated design. Over the 6 years 1997-2003, total fine litterfall and its components varied in complex ways across the fertility gradient and through time. The biomass of reproductive litterfall (flowers/fruits/inflorescences) varied by 32% among years, and in particular years the 2.5 to 6.5-fold among-plot differences in this litterfall component were highly correlated with soil characters (positively with total phosphorus and potassium, negatively with soil C:N and total carbon). Leaf litterfall varied seasonally in all years, peaking in periods of rainfall minima; it also varied significantly among years. Although the long-term plot-level means of leaf litterfall showed no significant variation across the within-forest edaphic gradients, in three years leaf litterfall was significantly positively correlated with soil C:N and total soil C stocks, and in all years it was negatively (but not significantly) related to soil phosphorus and cations. Our continuing studies will focus on the interacting processes that underlie these spatiotemporal patterns in fine litterfall, an ecosystem flux strongly linked to many other aspects of forest biogeochemical cycling.

CLARKE, FRANK^* and RACEY, PAUL^*, School of Biological Sciences, University of Aberdeen, f.clarke@abdn.ac.uk, Natural forest management in Trinidad, West Indies: implications for bat conservation.
Evaluating which logging systems are most compatible with the maintenance of biodiversity is of prime importance if tropical forests are to be managed in a sustainable way. Trinidad in the West Indies has a long history of forest reservation, protection, and management dating back to the establishment of the Forestry Department in 1901. We present the results of a two-year field study in Trinidad in which we examined the organisation and diversity of a bat community of lowland moist tropical forest and the responses of bats to different systems of natural forest management and plantation forestry. The Open Range (OR) system is a continuous harvesting system with few controls on felling, in common with most methods used to log tropical forests worldwide. The Periodic Block (PB) system is a polycyclic harvesting system with many controls on felling, hailed by the World Bank as an example of best practice management. A major aim was to evaluate whether these two systems of natural forest management are compatible with biodiversity conservation. We used a standardised sampling methodology employing mist nets at ground level and in the canopy, and harp traps to sample bats in primary forest, OR- and PB-managed forest, and Teak plantations. A total of 3,664 bats representing 50 species and eight families were recorded, accounting for more than 75% of Trinidad′s bat fauna. Bat species richness is unaffected by both systems of natural forest management but appears to be reduced in teak plantations. Both systems of natural forest management lead to a decrease in the abundance of gleaning animalivores and an increase in generalist frugivores. The PB system is most compatible with the maintenance of biodiversity and there is evidence of bat community recovery with post-logging forest recovery. We discuss the major threats facing Trinidad′s bats, attributes of the PB system that may account for its compatibility with biodiversity conservation, and examine what lessons that can be learned from Trinidad by other countries in tropical America and the Caribbean to reconcile the needs of economic forestry and wildlife conservation.

COCHRANE, MARK A.^*, 1405 S. Harrison Road, Room 101, cochrane@globalchange.msu.edu, Tropical rainforest fire dynamics: oxymoron or new evolutionary paradigm?
Until recently, fires in tropical evergreen forests have either been considered impossible or evolutionarily inconsequential. The extensive tropical forest fires, seen throughout the world in the late 1990s brought the tropical fire problem to the worlds attention, however temporarily. While news accounts of tropical forest fires are sporadic, fire disturbance is a continual and growing selective pressure against native species and environmental functioning. The causes of these forest fires are numerous. The vast majority are directly or indirectly linked to human activities, including deforestation fires, pasture and land maintenance fires, escaped fires from loggers and hunters, poorly managed trash, cooking or waste burning fires, arson, and other accidental fires. Land cover change is exacerbating the fire problem within the tropics. Forest fragmentation and land cover change interact synergistically to expose more of the forest to fire and consequently raise the risk of unintended fires occurring across the entire landscape. Selective logging activities and the legacy of previous fires diminish the remaining forests resistance to subsequent fires. Throughout the tropics, ignition sources continue to grow in number, while the probability that any given ignition event will start a forest fire increases as well. The new fire dynamic for many tropical forests is one of frequent fire incursions and rapidly increasing fire severity. These changes in the frequency, intensity and pattern of forest fires in the tropics represent a major fire regime shift. The tenants of disturbance ecology make it clear that, if fire incidence stays at current levels or increases in frequency, many rain forests will be replaced with less diverse, more fire tolerant, vegetation. Fire is now the greatest single selective pressure upon the species within many forests. Unless these trends are reversed, new ecosystem assemblages will result from the interplay of current evolutionary adaptations and changing fire dynamics?

COMITA, LIZA S.^*, Department of Plant Biology, University of Georgia, 2502 Plant Sciences Bldg, liza@plantbio.uga.edu, Seedling and Adult Habitat Associations in a Neotropical Tree Community.
Niche differentiation among species has been proposed to explain how high diversity may be maintained in tropical tree communities. Traditionally, studies of niche differences among tropical tree species have focused on variation in understory light levels. However, associations among tree species and topographically defined habitats have been observed in tropical forests worldwide and suggest that some species may specialize on local soil moisture levels, which are known to vary with topography. However, since most studies of habitat associations have focused only on adult distributions, it remains unclear at what life stage these associations begin to form. We conducted a community-wide census of seedlings and small saplings in the 50-ha Forest Dynamics Plot (FDP) on Barro Colorado Island (BCI), Panama. All woody plants > 20cm in height and < l cm dbh were mapped, tagged, measured, and identified in twenty thousand uniformly distributed 1-m2 plots. Using this data on the spatial distributions of seedlings, we test for associations between species and 5 different habitat types (slope, high plateau, low plateau, swamp, stream). We compare species associations at the seedling stage with results of a previous study of adult and sapling habitat associations in the BCI 50-ha FDP (Harms et al 2001). Seedlings and adults often have similar distributions due to limited seed dispersal making it difficult to determine whether seedling habitat associations are due to local dispersal or to higher survival in preferred habitats. Therefore, we also use previously calculated, species-specific dispersal curves to predict seed rain into different habitat types. We then compare the predicted density of seeds with actual densities of seedlings, saplings, and adult trees in various habitat types. Comparisons of species associations at various life stages allow use to determine when habitat associations are forming and offer insight into the mechanisms behind observed species habitat associations.

CORBARA, BRUNO^*, CANOPY GLIDER PROGRAMME, UNIVERSITE BLAISE-PASCAL, 34 AV. CARNOT, corbara@srvpsy.univ-bpclermont.fr, The Canopy-Glider : an innovative tool for biodiversity studies and conservational purposes.
The Canopy-Glider is an inflatable craft capable of flight which can be used as an observation and sampling tool for scientific and conservational purposes. Its conception is the result of years of experience acquired using the Canopy-Sledge developed by the Canopy-Raft Consortium. The Canopy-Glider, designed to carry three persons, uses a Roziere structure (the combination of a hot air dirigible and a helium balloon) and is propelled by powerful and totally innovative small gas jet engines. The Canopy-Glider has been designed to be highly efficient for brief flights with short intervening stops. It is particularly appropriate for the collection of botanical and zoological samples, in places that are otherwise difficult to reach. Consequently, the Canopy-Glider is an excellent tool for the : (1) systematic inventorying and sampling, at the upper canopy level, of the flowers and fruits of trees and lianas, the lianas themselves, epiphytes, lichens, mistletoes, etc ; (2) identification, rapid assessment, mapping, and photographic recording of critically endangered species of plants (insular endemic, micro-population, etc); (3) unobstrusive in situ collection of samples, including the tissues of rare plants for reference collections thus facilitating the ex situ conservation and/or reproduction of these same plants; (4) systematic sampling of invertebrates at the upper canopy level by means of branch beating, branch clipping etc; (5) placement of traps (light traps, flight interception traps, etc) and other sampling devices (artificial phytotelma, etc) on the top of trees. Moreover, as it has been the case for the Canopy-Sledge and other devices used during the Canopy-Raft expeditions, the Canopy-Glider R allows a great publicity around the scientific and conservation programmes it deserves. It is an excellent tool to promote and assist education and public awareness programmes in the field of conservation. The Canopy-Glider is involved in the ACCET Program (ACCET for Arthropod Communities and Canopy Ecology in the Tropics) which aims to examine factors that shape the distribution, diversity, abundance and composition of arthropod assemblages in the upper canopy across different rainforests.

CORDELL, SUSAN^* and SANDQUIST, DARREN R., USDA Forest service, 23 E. Kawili Street, scordell01@fs.fed.us, Constraints that beget functional variation of Hawaiian native tree species.
Few studies have made an explicit attempt to determine how phylogenetic variation and constraint might influence ecosystem processes and species interactions at the community level. The isolated nature of the Hawaiian Islands presents an exceptional opportunity to explore such questions because taxonomic diversity is limited but the opportunity for intraspecific diversification and adaptive radiation is high. As such contrasts between phylogenetic diversity versus phylogenetic constraint, and between diversity and adaptiveness, can be readily compared and placed within a functional context that helps to identify how such alternatives influence ecosystem processes. These comparisons are best exemplified by studies of the relatively monospecific Hawaiian wet forests versus the more diverse dry forests. In the former, functional diversity is dependent on adaptive variation within a single, highly variable species, Metrosideros polymorpha. In contrast, the functional variation in dry forests results from relatively high taxonomic diversity. A priori, one would expect the latter to have greater functional diversity, but the constraint of low phylogenetic diversity in wet forest systems appears to be offset by high phenotypic variation in Metrosideros. The contrasts between these two forests provide the basis for a unique examination of phylogenetic effects on ecosystem processes such as variation of, and constraints on, carbon balance, water relations and nutrient cycling

COZZA, JOHN^*, Biology Department, University of Miami, PO Box 249118, jcozza@fig.cox.miami.edu, Sex, Lies, and Begonias: Sex expression in a rainforest herb.
Although most plants express male and female functions together in each flower, about 5% of plants are monoecious (with separate male and female flowers on the same plant). This separation of the sexes can allow the ratio of a plant′s male and female flowers to vary, perhaps according to plant size, environment, or selection by pollinators. I studied the sex expression of Begonia urophylla in the Costa Rican premontane rainforest. B. urophylla is monoecious, temporally dioecious (plants change sex, with male flowers produced first) and is pollinated by deceit (female flowers offer no reward to pollinators and mimic males). Sex expression varied within populations and over time. In 2003, three populations showed a bimodal distribution of bud gender (ratio of female and male buds) of individual plants, with peaks at 0% female (all male) and 30-40% female. Many plants changed gender from the original allocation of buds to the flowers that actually opened. Plants that bloomed later in the season tended to be more male. The following year, the gender distributions in at least one population had the same peaks, but with relatively fewer males. In addition, more plants produced multiple inflorescences, allowing me to compare sex expression of sequential inflorescences. To explore why plants might abort buds and thus modify their original gender allocation, I shaded plants that had already developed buds and left matched plants unshaded. Plant size affected gender in 2003, but canopy openness, soil moisture, and soil N and P content did not. In 2004 more plants bloomed, there was a greater range of sizes, and I measured environmental variables more directly. Experiments under lights in the lab may help to tease apart the complex interrelationships of size, environment, and genotype in determining a plant′s gender.

CRAMER, JENNIFER M.^*, MESQUITA, RITA, VIZCARRA BENTOS, TONY and WILLIAMSON, G. B., Louisiana State University, Department of Biological Sciences, 107 Life Sciences, jencramer@yahoo.com, The effects of forest fragmentation on the seed dispersal of Duckeodendron cestroides, a Central Amazon endemic.
On a landscape, fragmentation of once continuous forest has dramatic effects on plant and animal populations. Where mutualistic interactions are prominent, such as in tropical rainforests, fragmentation may be even more disruptive, although few such studies exist. Here, we tested the effects of fragmentation on the seed dispersal of a tropical, emergent tree species by comparing dispersal curves in forest fragments to those in continuous, unfragmented forest. Duckeodendron cestroides, one of the many rare, endemic tree species of the Central Amazon, has large seeds with a thin exocarp and is dispersed by medium to large arboreal and terrestrial mammals. We censused the dispersal of Duckeodendron seeds at the Biological Dynamics of Forest Fragments Project from July to September of 2002, using wedge-shaped transects radiating from the center of each tree's crown. The percent of seeds dispersed more than 1 meter beyond the crown was dramatically different for continuous forest (49.8%) versus forest fragments of 100 ha (20.5%) and 10 ha (13.9%). For seeds dispersed beyond the parental tree's crown, a random coefficient regression analysis showed that dispersal in fragments and in continuous forest had the same slopes, indicating that seeds were proportionally distributed with distance in the same manner for both treatments. However, the intercept of the linear regression was higher in continuous forest, signifying that more seeds were dispersed to all distances beyond the crown in continuous forest than in forest fragments. These data demonstrate that fragmentation of tropical rainforest can have a profound, negative effect on a plant-animal interaction.

CRUZ-ANGON, ANDREA^*, GREENBERG, RUSSELL, GARCIA-FRANCO, JOSE G. and FLORES-PALACIOS, ALEJANDRO, Instituto de Ecologia, AC., km 2, Antigua Carretera a Coatepec, No 351, angon@ecologia.edu.mx, The importance of epiphytes for biodiversity conservation in coffee plantations in Central Veracruz, Mexico.
Epiphytes are a common element in shade coffee plantations. As an agronomic practice, some managers remove them from their tree hosts. We assessed the effects of this practice for biodiversity conservation in terms of the number of vascular epiphytes species that are loss due to this practice, and the effects that this practice may have on avian and insect communities. In 1999 and 2000 coffee farmers removed epiphytes form shade trees in two match pairs of plots in a coffee plantation in Central Veracruz, Mexico. Before epiphyte removal we assessed epiphyte diversity in the coffee plantation by sampling 51 trees (seven species) spread across the plantation and 45 trees of the dominant shade tree (Inga jinicuil). After the removal, we conducted daily bird censuses from August 2001 to March 2002. We also fogged and collected insects in three Inga jinicuil trees by plot (December 2001). Insects were sorted to morphospecies. Results: Total epiphyte richness was 57 species, this accounts for more than 60% of the floral diversity in the coffee plantation. Bromeliad species dominate the epiphyte community. Epiphyte diversity is comparable to the nearest forest site. Insect and avian diversity did not differ among plots with opposite treatment, but in both taxa mean abundances and hence, community structure was significantly different in plots with opposite treatment. Several forest-dependent bird species (18) were significantly more abundant in the with-epiphyte plots. Few species (3) were more common in the non-epiphyte plots and these species are associated with non-forest habitats. Several insect orders were significantly more abundant in epiphyte plots; only 1 order (Hemiptera) was significantly more abundant in plots without epiphytes. Our data corroborate the positive influence epiphytes have on fauna and that epiphyte removal, as an agronomic practice should not be promoted or encouraged.

CUARTAS, SANDRA and NÚÑEZ-FARFÁN, JUAN, Instituto de Ecología, UNAM Apartado Postal 70-275, Anexo Jardín Botánico, Ciudad Universitaria, UNAM, Mexico, scuartas@miranda.ecologia.unam.mx, Genetic structure of the tropical rainforest understory herb Dieffenbachia seguine L. in contiunous and fragmented forest.

Using isozyme markers, we examined the consequences of habitat fragmentation on the genetic diversity and structure of the clonal understory herb Dieffenbachia seguine. We sampled four populations within the continuous forest (640 ha) in order to have a replicated control of the former genetic structure of the species (undisturbed habitat) and six populations in remnant fragments differing in size from 0.3 to 137 ha. Leaves from 35 plants were sampled in each population for genetic analysis. Nine allozyme loci were analyzed. Allelic richness, polymorphism and heterozygosity showed no positive relationship with the size of the fragment. All populations showed deviation from Hardy-Weinberg equilibrium as indicated by the positive fixation coefficients. Genotypic richness was significantly lower in populations of fragments compared to populations in continuous forest. There was a significant positive relationship between fragment area and the number of unique genotypes and genotypic richness. F-statistics indicated that populations of D. seguine are highly structured as a result of random processes and inbreeding both in fragments and in continuous forest. The observed reduction in fruit-set and genotypic diversity associated to the smallest fragments suggest a possible effect of forest fragmentation upon the mating system of plants through a negative effect upon plant-pollinator interaction. Cluster analysis of the 10 populations using genetic distances, showed no association with geographic distances, yet the smallest isolated population is separated from all other populations by a high genetic distance value, suggesting random differentiation. Thus, conservation strategies should focus in maintaining large fragments in order to preserve genetic and genotypic variation of this species and to prevent the negative effects on pollinators populations, preserving the plant-pollinator interaction which is critical in the long-term persistence of populations.

CUAUTLE, MARIANA^*, Instituto de Ecología, A.C. Km. 2.5 Antigua Carr. a Coatepec No. 351, Congregación el Haya, Mexico, mcuautle2004@hotmail.com, Extrafloral nectaries plants and ant