Date of Award:

5-2023

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Committee Chair(s)

Noelle G. Beckman

Committee

Noelle G. Beckman

Committee

Claudia Nischwitz

Committee

Jim Powell

Committee

Kezia Manlove

Committee

Tal Avgar

Abstract

Plants and frugivorous animals exist in mutually beneficial relations, as these animals feed on fruits, ingest the seeds, and carry them away from the parent trees. Such dispersion of seeds over space helps them colonize new habitats, escape high mortality rates near their parent trees, and avoid competition with conspecifics. Therefore, seed dispersing animal movement can be critical for the persistence of plant populations. Yet what drives such seed disperser movement is often less understood and how it affects seed dispersal is little explored. In my dissertation, I investigate multiple drivers of seed disperser movement, link movement to potential seed dispersal patterns, and how such movement and thus seed dispersal can be impacted by anthropogenic impacts. In chapter 1, I develop a framework that can allow us to couple seed disperser movement with the seed dispersal patterns, by using information from different movement drivers and characterizing movement into different activity modes. In chapter 2, I show that the external environment can be an important driver of a tropical seed dispersers' movement and impact how far seeds are carried from their parent trees and the conditions they experience at their deposition sites. In chapter 3, I show that certain seed dispersers can account for multiple resource attributes while foraging, which in turn can affect their movement and hence seed dispersal patterns. Thus, seed dispersers' navigational capabilities can play important roles in their seed dispersal services. In chapter 4, using computer simulations, I showed that habitat loss can have stronger impacts on seed dispersal patterns such as long seed dispersal distances than habitat fragmentation, yet fragmentation impacts become more significant when habitat amount fell below a threshold. Finally, in chapter 5, I showed that the loss of large dispersers and therefore their movement from tropical ecosystems strongly reduced the long-dispersal seed dispersal of large-fruited plants. In summary, through my dissertation I showed that seed disperser movement is a critical component of plant seed dispersal.

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