Molecular evolution and historical biogeography of New World birds

Deciphering the patterns of how biodiversity has evolved across time and space has remained a fundamental objective for biologists for the last 200 years. Researchers are faced with the challenge of interpreting the complexity of evolutionary patterns that have been generated over the deep history of the Earth. The advancement of DNA sequencing technology has yielded a new and powerful genetic toolkit that has allowed biologists to address novel evolutionary questions. For my dissertation research, I used molecular genetics and a statistical framework to study the evolution and historical biogeography of birds distributed in North and South America. My dissertation encompasses three separate research projects that examined the relationship between changes in the Earth's climate and geology and the evolution of avian taxa. I examined evolutionary processes that operate on three different biological scales: within populations, among populations, and species' assemblages. For my first research project, I used a bird species as a model to determine the processes responsible for generating genetic diversity and structure in populations (Chapter 2). I showed that genetic diversity is not just affected by processes that operate over long evolutionary periods, but iv additionally genetic diversity is impacted by on-going processes. In my second research project, I evaluated the relationship between population size and the rate at which populations evolve (Chapter 3). For this project, I developed a new analytical framework using population genetic theory to show that small populations evolve faster than large populations. For my final research project, I showed how the formation of a land bridge between North and South America was critical for birds to disperse between continents (Chapter 4). Overall, my dissertation provides new insight into avian evolution by identifying processes across time and space linked to the genetic patterns observable in the birds of North and South America.