The Population History of Drosophila melanogaster and the Evolution of Ethanol Tolerance and Body Size, Adaptive Traits
[Thesis]
Sprengelmeyer, Quentin
Pool, John E.
The University of Wisconsin - Madison
2021
144
Ph.D.
The University of Wisconsin - Madison
2021
Drosophila melanogaster is a great model to use in untangling the evolutionary process of a novel trait. There are abundant molecular techniques, extensive genomic data, they have short generation time, and stocks can be maintained in the lab with relative ease. This dissertation uses these advantages to investigate the population history of D. melanogaster and the genetic basis of adaptive traits. First, I create a robust demographic model of D. melanogaster expansion throughout Africa and into Europe. Estimates from this analysis has this expansion throughout Africa starting ~13,000 years ago and crossing the Sahara relatively soon after and into Europe ~1,800 years ago. Second, I explore the genetic architecture of ethanol resistance found in multiple populations of D. melanogaster. Findings from this study include elevated ethanol resistance in three different populations and that ethanol and cold resistance may have a partially shared genetic basis. We also find that the genetic architecture of ethanol resistance evolution differs substantially not only between our three resistant populations, but also between two crosses involving the same European population. Finally, I investigate the evolution of two adaptive traits, thorax and wing size, found in a highland Ethiopia population. The results from this study show that genes with moderate to large and small effect contribute to both phenotypes and standing variation may have helped this population adapt to the novel habitat. We have also found there to variability in the genetic architecture within this population.