REU: Dynamics of Tropical Forest Seed Banks: Seed Predatorsas Determinants of Forest Regeneration Patterns and Plant- frugivore Coevolution

种子休眠机制在寄生于小规模扰动（例如，树木砍伐）的热带植物中很普遍，并且可能是因为分散将大多数种子存放在不适当的栖息地（例如，在完整的森林冠层下）而进化的。大多数殖民者确实在间隙形成之前到达，但在间隙信息之前种子在土壤中的典型“停留时间”是未知的。种子在土壤中存留的时间取决于它们被捕食者和超出生存能力固有极限“移除”的速度。从土壤中移除的速度对这些“先锋”植物及其所在的群落具有深远的影响：从自然或人为干扰中恢复的斑块中的物种组成在很大程度上取决于干扰时种子库的组成。此外，种子去除率调节了与不同成熟时间和不同动物传播相关的适应度增量。本研究将利用哥斯达黎加先锋植物的发芽要求、种子休眠和鸟类产生的种子阴影的广泛背景数据来评估这些影响。通过几个可控的、重复的田间实验，P.I.将测量种子输入和从土壤种子库中移除的速率，然后检查种子人口统计对群落结构、成熟物候和植物-传播者关系的演变的影响。这项工作将对分析热带森林动态具有重要意义。

Seed dormancy mechanisms are widespread among tropical plants that colonize small-scale disturbances (e.g., treefalls),and presumably evolved because disperses deposit most seeds in inappropriate habitats (i.e., beneath intact forest canopies). Most colonists indeed arrive before gap formation, but the typical "residence time" of seeds in the soil before gap information is unknown. How long seeds persist in the soil is dependent upon the rates at which they are "removed," both by predators and by exceeding inherent limits of viability. Rates of removal from the soil have profound consequences for such "pioneer" plants and the communities in which they occur: species composition in patches recovering from natural or anthropogenic disturbance is largely determined by the composition of the seed bank at the time of disturbance. In addition, seed removal rates mediate the fitness increments associated with different ripening schedules and with dispersal by different animals. This study will take advantage of extensive background data on germination requirements, seed dormancy, and bird-generated seed shadows in Costa Rican pioneer plants to evaluate these effects. Through several controlled, replicated field experiments, the P.I. will measure rates if seed input to and removal from the soil seed bank, and then examine the consequences of seed demography for community structure and the evolution of ripening phenologies and plant-disperser relationships. This work will have important implications for analyses of tropical forest dynamics.