Postzygotic isolation in Drosophila simulans and D. mauritiana

The study of speciation requires examination of barriers that produce and maintain species separation. Using Drosophila simulans and D. mauritiana, this thesis focuses on post-zygotic isolating mechanisms, which occur after the formation of interspecies hybrids. This study aims to examine the genetic causes of male hybrid sterility and decreased hybrid female lifespan. Quantitative trait locus (QTL) mapping using flies with an attached-X chromosome, identified seven autosomal QTLs that contribute to hybrid sterility. Separately, reduction in hybrid female lifespan was noted for females bearing an attached-X chromosome and was more severe in individuals who were mated. This reduction is caused by a recessive factor on the X chromosome interacting with a dominant autosomal factor. This study is the first to create a hybrid sterility QTL map in Drosophila simulans and D. mauritiana and also succeeded in characterizing the understudied phenomenon of reduced hybrid lifespan in this species pair.