Dissertation Research: Empirical and Theoretical Studies of Seed Dispersal in Jacaranda copaia.

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The primary objective of the study is to directly measure seed dispersal distances and differential deposition patterns in a common, wind-dispersed, gap colonizing tropical tree, Jacaranda copaia. Dispersal will be measured by genotyping maternal tissue surrounding dispersed seeds captured in large seed trap arrays. These will be matched to adult genotypes within the mapped population. The data will be used to answer the following questions: (1) How frequent is long distance seed dispersal (here defined as dispersal at distances greater than 100m) in Jacaranda? How does long distance dispersal vary within and among years? (2) How well do current inverse and mechanistic dispersal models estimate and predict dispersal patterns measured above? (3) What biotic and abiotic factors determine dispersal distances? And (4) Are Jacaranda seeds disproportionately dispersed to tree fall gaps?As humans continue to alter and fragment tropical forest landscapes, knowledge of the processes that regulate populations and maintain diverse communities is critical for predicting how these populations will respond in the future. Dispersal is chief among the processes that will determine the ecological and population genetic response over time and space. There is a considerable void of data on the frequency, patterns, and mechanisms of seed dispersal within and among natural plant populations. This study is among the first and most comprehensive attempts to obtain direct measurements of seed dispersal distances using genetic techniques. It will directly inform conservationists and land managers about the appropriate size of habitat required to maintain populations of tropical trees in light of the spatial extent of seed movement.