Individual mating decisions and hybridization

Abstract

The dynamics of gene flow among populations ultimately depend on behavioural interactions among individuals (Ritchie, 2007), construed in the broadest sense to encompass chemical and mechanical interactions in plants and microorganisms. The mechanisms underlying mate choice can, therefore, determine whether hybridization promotes or retards speciation. Further, the nature of the processes underlying mating decisions imposes important constraints on their role as agents of selection. Understanding the evolutionary genetics of hybridization requires a more detailed consideration of what determines mating interactions among individuals. For hybridization to have notable evolutionary consequences, two things have to happen: first, matings have to occur between males and females from divergent populations and second, hybrids have to mate with each other and/or backcross to parentals. There is a growing body of evidence to suggest that behavioural barriers to interspecific mating are brittle and susceptible to environmental perturbation. Once hybridization occurs, novel suites of signals and novel suites of preferences can facilitate backcrossing to parentals or, alternatively, can lead to hybrid speciation. I will discuss each of these processes in turn.