Committee Chair

Hayes, Loren

Committee Member

Gaudin, Timothy; Klug, Hope


Dept. of Biological and Environmental Sciences


College of Arts and Sciences


University of Tennessee at Chattanooga

Place of Publication

Chattanooga (Tenn.)


Evidence suggests that harsh and variable environmental conditions modulate the fitness benefits associated with increased group size in some species. Social network analysis is a more powerful approach to examine this relationship, as the quality of interactions is more important than quantity. Using 9 years of data, I determined how mean and coefficient of variation (CV) of nine ecological variables modulated the relationship between social network metrics on direct fitness in the plurally breeding rodent, Octodon degus. As predicted, increased social structure was most beneficial when food abundance was more variable, mean monthly rainfall was highest, predator abundance was more variable, soil hardness was more variable, and ectoparasitic flea intensity was low and more variable. In contrast, the observed effect of the CV of burrow density and mean food abundance on the relationship between strength and direct fitness contradicted our predictions. Overall, our results illustrate that the harshness and unpredictability of ecological conditions are not mutually exclusive explanations for social structure-direct fitness covariation.


I would like to begin by thanking my incredibly dedicated advisor, Dr. Loren Hayes, and my thesis committee members, Dr. Hope Klug and Dr. Tim Gaudin. Their guidance has been invaluable throughout the project design and writing process. I would also like to thank Dr. Luis Ebensperger and his lab members at the Universidad Católica de Chile, without whom this project would not exist. Specifically, I would like to thank Dr. Sebastian Abades for his guidance using the program R. Additionally, for their vital statistical assistance, I would like to thank Dr. Joydeep Bhattacharjee, Dr. Cuilan Gao, and Garrett Davis. Additionally, I would like to thank all of the amazing graduate students at the University of Tennessee at Chattanooga for being my support system. In particular, I would like to thank the students that helped me proof read and finalize this document: Josh Ryan and Madeline Strom. Finally, I would like to thank Winston Theodore Carroll.


M. S.; A thesis submitted to the faculty of the University of Tennessee at Chattanooga in partial fulfillment of the requirements of the degree of Master of Science.




Degus; Behavioral assessment -- Animal models; Rodents -- Behavior; Social behavior in animals


social structure; social network analysis; communal rearing; ecological effects; fitness effects; habitat conditions; spatio-temporal variation


Environmental Sciences



Document Type

Masters theses


xiii, 109 leaves





Date Available