Abstract:
Understanding the process of speciation requires investigation of traits that can lead to divergence between populations. This thesis examines the genetic basis of variation in red pigmentation in flowers and vegetative tissues, traits that may contribute to reproductive isolation in the Mimulus aurantiacus (bush monkeyflower) species complex. Utilizing a series of genetic crosses that segregate for color differences, I analyzed differences among taxa in flower color patterns and vegetative anthocyanin content to investigate the genetic basis for the repeated emergence of these traits. I provide evidence that the genetic basis of red flowers differs between the two red-flowered taxa in the M. aurantiacus species complex: M. parviflorus and the red ecotype of M. puniceus. These results suggest parallel evolution of this trait. I also further characterize the role of the gene MaMyb1 in influencing flower color. Finally, I add to previous evidence that suggests a correlation between vegetative and floral anthocyanins, substantiating the possibility that variation in this trait contributes to reproductive isolation. These findings add to our understanding of how reproductive isolation may have evolved in M. aurantiacus and motivate further investigation concerning the origins of these traits that were essential for the initial stages of speciation in this group.