Degree

Doctor of Philosophy (PhD)

Department

Biological Sciences

Document Type

Dissertation

Abstract

For species living in dominance hierarchies, social rank dictates access to resources and often contributes to reproductive success. To ensure survival, individuals constantly evaluate trade- offs between crucial biological systems, like the reproductive and immune systems, depending on their social rank and physiological state. Little is known about how social species balance interactions between immune system function, fluctuations in social status and reproductive fitness, and the performance of behaviors necessary for maintaining social status when sick, particularly in fishes, the largest and most diverse group of vertebrates. My dissertation research uses a whole animal approach to examine how physiological profiles impact the strength of the immune response and how activated immune response impact behavioral output in the cichlid fish, Astatotilapia burtoni. First, I found differences in the strength of inflammatory response and distinct cytokine expression networks between male and female fish of different reproductive states and social statuses. Reproductively active gravid females displayed greater inflammatory response than dominant males when injected with an experimental inflammatory stimulant. Females of all reproductive states also showed greater gene expression of proinflammatory markers when compared to both dominant and subordinate males collectively. Next, I explored how an activated immune response disrupts aggressive behaviors between dominant males during agnostic male-male interactions. Experimental males injected with the immunostimulant lipopolysaccharide (LPS) were more likely to lose fights during behavioral trials, performed greater submissive and fewer aggressive behaviors. LPS-injected males also showed different expression of proinflammatory markers in the brain and major immunological organs when compared to vehicle-injected controls. Finally, I introduce a new method that allows users to identify atypical modes of trait evolution within phylogenies. Evolutionary biologist greatly depends on phylogenetic comparative methods to make assumptions of how groups of species evolved, therefore, it is imperative to assure that statistical test address appropriate questions and the proper interpretation of results. Overall, these results provide the first examples of ways that an upregulated immune system can alter the function of other biological systems in Astatotilapia burtoni and introduce a novel method useful to evolutionary biologist.

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Date

1-23-2023

Committee Chair

Maruska, Karen P.

DOI

10.31390/gradschool_dissertations.6044

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