UC Santa Barbara

The world’s lands and oceans are currently being irrevocably altered by anthropogenic change, including the combined impacts of species extinctions, species invasions, land use change, and climate change. In the face of these shifts, understanding the fate of biological communities as a whole becomes imperative to slow or mitigate the extinction of species and the loss of ecosystem functions. Understanding how biological communities have and continue to respond to human activity includes both a) considering the conservation outcomes of interventions to curb biodiversity loss as well as b) using new and emerging methods to understand how individuals and species interact to shape biologically complex interaction webs (e.g. food webs). In this dissertation, I use the island ecosystem of Palmyra Atoll (Central Tropical Pacific) to understand both a) the ecosystem-level effects of the loss of plant-herbivore interactions following an invasive rodent eradication and b) the patterns and biological rules that shape individual- and species-level predator-prey interactions by developing and using emerging DNA metabarcoding methods. Together, this work aims to paint a better picture of the ecosystem-wide effects of species interactions and what losing them might mean for ecosystems beyond Palmyra Atoll.