Date of Award

12-10-2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Neuroscience Institute

First Advisor

Walter Wilczynski

Second Advisor

Laura Carruth

Third Advisor

Kim Huhman

Fourth Advisor

Bingzhong Xue

Abstract

Green anole lizards have been used as a model for studying aggression and other social behaviors due to their easily studied stereotypical displays during aggression and courtship. Formation of dominance hierarchies is a common phenomenon observed in many vertebrate species. A change in social status impacts all aspects of an individual’s life including its behavior, physiology, and nervous system. In this dissertation, I aimed to further insights from previous studies in green anoles on the behavioral, physiological and neurobiological effects of social status in dominant-subordinate dyads. To understand behavioral changes, I investigated changes in aggression, courtship and exploratory behavior before and after acquisition of social status. Subordinates showed lower levels of aggression and courtship whereas dominants showed higher levels of exploratory behavior after acquisition of social status. Such differences were absent before acquisition of social status. In terms of energetic changes, I investigated changes in hepatic and muscle glycogen, plasma glucose levels, and body fat levels. Dominants showed higher levels of hepatic and muscle glycogen but changes in blood glucose levels were absent. Dominant anoles also exhibited higher levels of body fat/ body weight ratio as well as a trend towards higher absolute body fat levels. I examined neurobiological effects of social status on anoles by conducting quantitative cytochrome oxidase histochemistry. Cytochrome oxidase is a rate-limiting enzyme in the electron transport chain and tracks neuronal metabolic activity. After 11 days of cohabitation, I observed higher levels of cytochrome oxidase activity in the medial preoptic area (POA) but not the amygdala or the septum. This is consistent with the role played by the POA in aggression and courtship. Furthermore, I found a positive correlation between cytochrome oxidase activity in the POA and hepatic glycogen levels. Findings from this dissertation extend our understanding of the impact of social status on green anoles and like the aforementioned correlation serves as the initial step towards understanding behavior in an integrative manner.

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