Dissertations, Theses, and Capstone Projects

Date of Degree

6-2024

Document Type

Thesis

Degree Name

M.S.

Program

Cognitive Neuroscience

Advisor

Sebastian G. Alvarado

Subject Categories

Animal Studies | Social and Behavioral Sciences

Keywords

Behavior, Social Behavior, Sociobiology, Cichlid, Astatotilapia burtoni

Abstract

Social systems provide robust frameworks for the division of labor and the allocation of resources that improve the fitness of a community. These social systems are pervasive across the animal kingdom and are seen in various species of insects, mammals, birds, reptiles, and fish. Within social hierarchies, rank can be dynamic and modulated by changes in molecular and/or physiological substrates. These changes can shape various behavioral outcomes that lead to the reorganization of hierarchies and their communities. Specifically, the role of social behavior in African cichlids has been salient for their adaptive radiations in the East African Great Rift Lakes underlining the importance of social behavior for diverse evolutionary outcomes. While it has been widely reported that cichlids have complex social lives, little remains known about how environmental variables can prime the social behaviors of males and females. Here we sought to better understand this phenomenon with two studies that ask the following questions: (1) Does social environment and rank shape spawning behaviors and outcomes of males? and (2) Does the visual ecology of females shape their preferences for differently colored males?

To address these questions, we adopted the African cichlid, Astatotilapia burtoni, that is indigenous to Lake Tanganyika. The cichlid's notable phenotypic diversity, particularly in male coloration and social behaviors, is believed to be a consequence of intense sexual selection and male-male competition, making them an invaluable resource for evolutionary studies.

Firstly, while previous studies have shown how territorial/non-territorial/ascending/ descending males have unique behavioral profiles, we sought to deepen this interpretation with a focus on the latency of decision-making and transition matrices representing enriched sequences of behavior. We investigated whether their past experiences in the social hierarchy—where some were stably territorial while others were non-territorial—affected their behavioral patterns as ascending males. We found that ascending males developed similar behavioral repertoires to stably territorial males, but ascending males still failed to mate with females.

Secondly, by investigating female responses to male cues, we aimed to learn how female sexual selection can be modulated by male phenotypic plasticity. We found that females did not have a preference between blue and yellow colors, despite being reared in one of those colors.

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