The evolution of conspecific gamete precedence and its effect on reinforcement

Conspecific gamete precedence, the usage of conspecific sperm by a female that mates with both a conspecific and a heterospecific male, has been found in many taxa. We construct a population genetic model to examine the evolution of conspecific gamete precedence and its coevolution with premating isolation in the process of reinforcement. Our findings suggest that conspecific gamete precedence can evolve via a process very similar to reinforcement. We explore the nature of the selection against hybridization necessary to drive this evolution. Moreover, our results confirm the prediction of Marshall et al. (Trends Ecol. Evol. 2002;17:558-563) that conspecific gamete precedence will inhibit the evolution of reinforcement between two species. We further find that reinforcement will inhibit the evolution of conspecific gamete precedence. Both reinforcement and conspecific gamete precedence increase reproductive isolation and contribute to the process of speciation. We discuss factors that may affect which of these phenomena are likely to become predominant between incipient species.