Skip navigation
Please use this identifier to cite or link to this item:
Title: The Behavioral Ecology and Host-Parasite Dynamics of the Zebras of East Africa
Authors: Tombak, Kaia Juulia
Advisors: Rubenstein, Daniel I
Contributors: Ecology and Evolutionary Biology Department
Keywords: Darwin's hostile forces
Host-parasite dynamics
Social behavior
Social evolution
Subjects: Ecology
Evolution & development
Issue Date: 2019
Publisher: Princeton, NJ : Princeton University
Abstract: Species- or population-typical social organization is thought to result principally from the interplay between predation risk, resource distribution, and pathogen transmission risk. This thesis explores the ecological basis of social behavior in two socially-divergent zebra species – the Grevy’s zebra and the plains zebra – with a focus on host-parasite dynamics in each. The first chapter details a study of group size variation in each species conducted via photographic censuses of zebra groups at sites with different lion densities from 2015-2018. We found that Grevy’s zebras increased group size in the wet season, consistent with food-limited grouping behavior, whereas plains zebras increased group size in the dry season, in line with group sizes limited by water or by pathogen transmission risk. The second chapter investigates differential exposure risk as the basis for higher parasitism by gastrointestinal nematodes found in plains zebras. As arid-adapted equids that need to drink infre-quently, Grevy’s zebras can range much farther from water than plains zebras and graze in areas with lower dung density, and therefore lower exposure risk, as a result. The nematode community, or nemabiome, of each zebra was analyzed in Chapter 3, where nematode species co-occurrence analyses revealed evidence for a preponderance of positive species associations, potentially indicating facilitative relationships and a need for host resistance to regulate populations. The fourth chapter explores the genetic vs. environmental determinants of host immune strategies and parasitism in a zebra hybridization zone. The results suggest that Grevy’s zebras not only experience lower exposure risk, but are genetically more resistant to gastrointestinal parasites than plains zebras. Taken to-gether, our findings indicate that gastrointestinal nematodes impose more pressure on plains zebras than on Grevy’s zebras, congruent with the grouping behavior studied in Chapter 1. Pathogen transmission risk is not as well understood in relation to social behavior as are the other ecological determinants of social systems, and this thesis attempts to bridge this gap in our understanding of social evolution through studies on the zebras of East Africa.
Alternate format: The Mudd Manuscript Library retains one bound copy of each dissertation. Search for these copies in the library's main catalog:
Type of Material: Academic dissertations (Ph.D.)
Language: en
Appears in Collections:Ecology and Evolutionary Biology

Files in This Item:
File Description SizeFormat 
Tombak_princeton_0181D_13164.pdf14.96 MBAdobe PDFView/Download

Items in Dataspace are protected by copyright, with all rights reserved, unless otherwise indicated.