Maya Woolfolk Thesis Defense (Hopi Hoekstra and Cliff Tabin, Co-Advisors)

Title: The evolution of neonatal vocal behavior in deer mice

Abstract:  Understanding the proximate and ultimate mechanisms that drive natural trait variation in populations is a major goal in evolutionary biology. Here, we take advantage of the extensive ecological, behavioral, and morphological variation across closely related species of deer mice (genus Peromyscus) to uncover the genetic and morphological mechanisms that underlie variation in an innate behavior: mammalian neonatal vocalization. In chapter 1, we performed behavior experiments in deer mouse species and hybrids to investigate the genetic architecture and functional significance of two different deer mouse vocalization types. We discovered that vocalization types are functionally distinct and have mostly separable genetic contributions. In chapter 2, we applied comparative morphology approaches to characterize interspecific differences in laryngeal morphology and identify morphological features associated with variation in acoustic structure of vocalizations. We described and quantified species differences in laryngeal morphology and utilized hybrids to demonstrate links between larynx structures and acoustic variation. In chapter 3, we used a forward genetic approach to determine the genetic basis of variation in vocal behavior between two pairs of closely related species. We found that multiple loci across the genome are associated with species differences in acoustic and temporal features of neonatal vocalization, and both shared and distinct loci contribute to the evolution of similar phenotypes. Together, these studies provide insight into the factors underlying variation in an important trait for the solicitation of parental care and survival, and contribute to our understanding of the genetic and morphological bases of behavioral evolution.

Committee: Hopi Hoekstra (Co-Advisor), Cliff Tabin (Co-Advisor), Dan Hartl (Chair), Ben de Bivort