PARENT SESSION
Oral Session # 92: Biogeography IV: Dispersal.
Presiding: J Choo
Friday, August 8. 8:30 AM to 12:00 PM, SITCC Meeting Room 104.
Linking dispersers and seed fate: Seed arrival and survival in a neotropical tree.
Hardesty, Britta Denise *,2, 2 Smithsonian Tropical Research Institute, Panama City, Panama
ABSTRACT- Seed dispersal is a fundamental process that shapes plant communities at local and large scales in both space and time. From the animal perspective, researchers assess disperser movement patterns, generally addressing seed deposition without empirical evidence of seed fate. From the plant perspective, ecologists have traditionally relied on seed traps and other indirect measures of determining seed shadows and dispersal curves. Recent advances in molecular techniques now permit analyses of gene flow via seed dispersal using maternal tissue from seeds, and enable us to determine genetic relationships among large numbers of individuals and populations of plants at widespread geographic scales in contemporary and historical time. Using microsatellite genetic markers developed for the vertebrate-dispersed dioecious tropical tree, Simarouba amara, I inferred the parentage of seeds and seedlings in the Barro Colorado Island 50 ha plot and related this to fine-scale spatial genetic structure and successful seed arrival and survivorship near and far from the parent plant. The spatial distribution of parents and their offspring, coupled with field measures of floral and fruit production, crown area and tree height, was used to calculate relative reproductive success and the frequency of long-distance seed and pollen movement. The dispersal dynamics examined here provide insight into a demographic filtering stage that is critical for generating forest structure. This study assesses the relative importance of gene flow via pollen versus seed with respect to distance, thus gaining insight to the role of frugivores in structuring plant communities at multiple forest sites characterized by high species richness and tree density, but with different ecological histories.
Key words: tropical forest, population genetics, seed dispersal,