Understanding "reinforcement", an evolutionary process that can lead to the origin of new species and generate species diversity

The integral question of how species are formed is currently receiving unprecedented research attention. Whether the process of reinforcement (selection against maladaptive hybridization) can produce new species is particularly controversial due to a lack of strong empirical data and untested theoretical objections. In a frog system in which two genetic lineages meet in two different contact zones, I recently demonstrated that speciation by reinforcement occurred at one contact zone but not the other. Here I will elucidate the factors that determined the different evolutionary outcomes at each contact zone and, in doing so, will greatly advance our understanding of the determinants and importance of this speciation mechanism in nature.