Undergraduate Honors Theses

Thesis Defended

Spring 2011

Document Type

Thesis

First Advisor

false

Abstract

Obligate brood parasitism, the act of reproducing by exploiting the parental investment of a host species to raise young, is fairly well known among bird species (Cruz et al. 2004 Encycl. Anim. Behav. ed. M. Bekoff. Greenwood Press, Westport, Conn). There is, however, only one known fish species that is an obligate brood parasite: Synodontis multipunctatus from Lake Tanganyika in Africa (Cruz et al. 2004 Encycl. Anim. Behav. ed. M. Bekoff. Greenwood Press, Westport, Conn). S. multipunctatus was identified as an obligate brood parasite by Sato in 1986 (A brood parasitic catfish of mouthbrooding cichlids in Lake Tanganyika. Nature. 323, 58-59), yet the ecology of the system is still understudied. A review of the literature indicates that knowledge of the precise cues that allow S. multipunctatus to spawn at the correct time could contribute to a deeper understanding of both the ecology and the evolution of the system. Yet, the cues are currently not fully understood. In a series of three experiments, where the amount of time that S. multipunctatus spends in preference zones in a bilateral visual preference setup is recorded to demonstrate visual preference, this paper aims to examine the nature of these visual cues. An experiment first evaluates the use of video playback as a valid research technique with S. multipunctatus. Results indicate that S. multipunctatus can see and respond to video as a stimulus in a way that is statistically comparable to live fish as a stimulus. Video playback is then used to compare S. multipunctatus preference for the visual spawning sequence of a host (Ctenochromis horei) versus a nonhost (Amatitlania nigrofasciata) species, with no significant differences found. Finally, live fish are used as stimuli to compare the preference between two endemic host species, Ctenochromis horei and Simochromis diagramma, that are naturally parasitized to differing degrees, with no significant differences. There are many potential explanations for the lack of significant results, including limitations in the experimental design; further experimentation is therefore necessary to reach definitive conclusions. Results did indicate that S. multipunctatus physically moves significantly more often when in a pair than when alone, indicating that the social structure of S. multipunctatus plays an important role in the parasitic system.

Share

COinS