Date of Award

Spring 1-1-2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ecology & Evolutionary Biology

First Advisor

Alexander Cruz

Second Advisor

Robert P. Guralnick

Third Advisor

William Lewis

Fourth Advisor

Michelle Sauther

Fifth Advisor

David Stock

Abstract

Obligate brood parasitism (completely relying upon a host for successful breeding) has been studied in insects and birds, with a considerable amount of research concentrating on birds such as cuckoos and cowbirds. The Lake Tanganyikan cuckoo catfish (Synodontis multipunctatus Siluriformes: Mochokidae) is the only known non-avian obligate brood parasite among vertebrates, and it uses female mouthbrooding cichlids (Perciformes: Cichlidae) as hosts. Although the basic breeding mechanism of the cichlid-cuckoo catfish system has been well documented through a series of observational studies, there have been few manipulative experiments concentrating on host-parasite interactions. The goal of my dissertation work was to examine this parasitic relationship from the perspectives of both the host and the parasite in the context of ecology and coevolution. Specifically, I was interested in how hosts avoid or mitigate parasitism, as well as features of the parasite that allow for successful parasitism. First, I assessed parasitism frequencies among cichlid hosts and discovered that sympatric Lake Tanganyikan hosts were parasitized significantly less than allopatric hosts from other lakes in laboratory conditions, possibly explained by subtle differences in mating ritual and oviposition, or increased aggression by sympatric hosts. Next, I compared unparasitized and parasitized broods to show that the cuckoo catfish indiscriminately parasitize all sizes of host, followed by complete elimination of host progeny and subsequent cannibalism while being brooded in the host mouth. Finally, using live fish and video playback techniques, I found that visual cues play an important role in breeding synchrony between the cuckoo catfish and cichlid hosts. Together, my dissertation provides the groundwork for using this unique cichlid-cuckoo catfish system as a model for studying brood parasitism in controlled laboratory conditions, where questions regarding parasitism dynamics in the context of both ecology and coevolution can be addressed.

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