Benefits of seed dispersal for plant populations and species diversity

Abstract

Seed dispersal influences the diversity and distribution of plants in ecological communities, and animals are the major vector of dispersal in the world's most biodiverse ecosystems. Defaunation occurring at the global scale threatens a pervasive disruption of seed dispersal mutualisms. Understanding the scope of this problem and developing predictions for the impact of seed disperser loss on plant diversity requires knowledge of the ways in which dispersers benefit their plant mutualists and how the loss of these benefits influence plant population dynamics. The first chapter explores novel benefits of seed dispersal in a wild chili from Bolivia caused by the reduction of antagonistic species interactions via gut-passage by avian frugivores. The second chapter measures how movement away from parent plants influences species interactions for three tree species in the Mariana Islands, assessing the source of distance-dependent mortality. The third chapter quantifies demographic impacts of density-dependent mortality in the forest at Barro Colorado Island, Panamá. The last chapter uses network concepts and information of the benefits of mutualisms to improve coextinction predictions within plant-animal mutualistic networks.