Degree

Doctor of Philosophy (PhD)

Department

Biologocial Sciences

Document Type

Dissertation

Abstract

Social animals must constantly assess their environment to make appropriate decisions. In several fish species, chemosensory signaling is crucial for social communication, conveying information on sex, reproductive state, and social status. Despite its importance in fishes, relatively little is known about how they employ chemical signaling, with only a few of the over 30,000 extant species investigated thus far. Further, there is a scarcity of information about where and how socially-relevant chemosensory signals are processed in the brain of fishes, or how chemosensory signals are integrated with other senses to elicit appropriate behaviors. For my doctoral research, I examined the role of chemosensory signaling during social interactions in a model cichlid fish, Astatotilapia burtoni. I also examined neural activation patterns in various social contexts to understand how socially-relevant visual and chemosensory signals are processed in the brain. Finally, I examined levels of putative pheromone-detecting receptors in the olfactory epithelium of juveniles and adults of varying social and reproductive status to gain insight into peripheral processing of sexually-relevant olfactory signals. I found that, similar to A. burtoni males, females use contextual urine release with higher urination rates in the presence of dominant males (reproductive context) and brooding females (aggressive context). Using in situ hybridization for the immediate early gene cfos as a proxy for neural activation, I identified key brain regions involved in mediating these context-specific behaviors. Further, I show that dominant males have altered behavioral and neural responses to visual and chemosensory signals from receptive females, which supports nonredundant signaling. Finally, using quantitative PCR I evaluated gene levels of all six putative pheromone detecting receptors, oras, in the olfactory epithelium and found that expression of some oras varies with reproductive status in females but not males. These data reveal the neural substrates mediating intra- and inter-sexual social behaviors in a single fish species, advancing our understanding of how socially-relevant chemosensory information is processed in the brain. It also provides the framework for examining how olfaction is integrated with other sensory modalities in the brain to mediate social communication and adaptive behavioral decisions across vertebrates.

Date

7-6-2018

Committee Chair

Maruska, Karen

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