Doctor of Philosophy

in the

School of Biological Sciences

Linh Chau

Will defend her thesis

“Population genetics and genomics of eusocial animals”

Friday, October 20th, 2017

3:00 – 4:00 PM

Marcus Nanotechnology Building, Room 1116

Thesis Advisor

Dr. Michael A. D. Goodisman

School of Biological Sciences

Georgia Institute of Technology

Committee Members

Dr. Soojin V. Yi (Biological Sciences)

Dr. Patrick T. McGrath (Biological Sciences)

Dr. Nicole M. Gerardo (Emory University, Department of Biology)

Dr. Joseph R. Mendelson III (Zoo Atlanta and Biological Sciences)

ABSTRACT

Major evolutionary transitions have been associated with increases in organismal complexity. One of the latest evolutionary transitions is from solitary life to eusociality. This transition led to a reproductive division of labor in which individuals are divided into castes. Reproductive castes are responsible for reproduction, while nonreproductive castes take part in colony maintenance and brood care. This division of labor represents a challenge to selection and has long been of curiosity to researchers. My dissertation research examined the population genetics and genomics of eusociality in a spectrum of eusocial species. First, I examined the population structure and genetic diversity of Vespula pensylvanica, a wasp native to North America that has invaded the Hawaiian archipelago. I found a lack of population structure in V. pensylvanica’s native range and determined how the population structure of invasive social insects can be shaped by geography. I also examined the population genetics of captive naked mole rats, one of the only known eusocial mammals.  I sought to understand how captivity can shape the population structure of a eusocial animal. Interestingly, there was evidence that naked mole rat populations are not as inbred as previously theorized and that sex ratios are equal within captive colonies. Finally, I examined how the phenomenon of gene duplication can affect the evolution of castes in eusocial species. I uncovered a relationship between duplication rate and level of sociality across the bees. Also, I saw that duplicates were differently expressed across phenotypes compared to single copy genes. These studies provide insight on an array of population genetic and genomic questions concerning the evolution of eusociality. Therefore, this research furthers our understanding of the rare distribution of this social system across the tree of life.