Using squamate systems to understand molecular underpinnings of evolutionary processes

Abstract

The solidification of evolutionary biology as a scientific theory provided a foundation for understanding the source of life’s variation, an objective that has since become a central aim in biology. While scientific acceptance of evolution answered some biological questions, it created and continues to create more questions than it has answered. Several questions being studied across the globe include (1) “How are species formed?” (2) “What factors influence trait evolution?”, and (3) “How do changes in genetics and environment determine how phenotypes respond to selection?” Squamate reptiles, the most species-rich group of tetrapods, are a diverse natural resource for empirical approaches to understanding biological questions. Within this dissertation, I utilize three squamate reptile systems (the species complex of spotted flying lizard Draco maculatus, the north American whiptail lizards Aspidoscelis, and the western terrestrial garter snake Thamnophis elegans) to answer questions regarding causes of lineage diversification, consequences of asexual reproduction, and genomics of life history evolution. I integrate results from molecular phylogenetics, whole-organism performance, mitochondrial physiology, and population genomics to test the riverine barrier hypothesis, the association of asexual reproduction with mitochondrial respiration, and the genetic underpinnings of senescence. Finally, I discuss the role of the mitochondrion in shaping evolutionary patterns, examine findings from this dissertation in broader biological and societal contexts, and provide recommendations for future endeavors to further tease out answers to these complex questions.