Selection on differential reproductive success of males and females (sexual selection) has been linked to speciation by driving divergence in both a male trait and the female preference for that trait. However, this process should not apply to the diversification of traits selected via male-male competition rather than female preference. Such traits may nevertheless facilitate speciation if involved in species recognition, and be favored if mating among species is disadvantageous (i.e., reinforcement against hybridization). This project investigates orangethroat and rainbow darters, representatives of a speciose fish clade with diverse and distinctive male breeding coloration. In both, competition between males affects their reproductive success while female preference does not. The research will incorporate (1) preference experiments to test whether male coloration mediates species recognition, (2) field surveys to examine the factors underlying male color diversification, and (3) a breeding design to measure hybrid inviability and thus the potential for reinforcement.
This project will elucidate the poorly understood relationship between speciation and male-male competition, a major aspect of sexual selection. Additionally, there will be opportunities for science education through participation in public outreach events involving native aquatic fauna, as darters make attractive and accessible subjects for teaching about ecology, evolution, and conservation. Finally, this project will mentor undergraduates in evolutionary concepts and the process of scientific inquiry.
