Title: Understanding species formation: a phenotypic approach.

Abstract:

Dobzhansky played a central role in our understanding of speciation by using simple 2-locus fitness landscape models. Over the past 30 years, research in speciation genetics has uncovered many robust patterns in intrinsic reproductive isolation, and fitness landscape models have been useful in interpreting these patterns. Here we examine fitness landscapes based on Fisher’s geometric model. Such landscapes are analogous to models of optimizing selection acting on quantitative traits. We show that Fisher’s model can generate all of the major findings of speciation studies (including “speciation genes” with strong deleterious effects in the sister-species background). Fisher’s model can also explain conflicting empirical results about the rate at which incompatibilities accumulate with genetic divergence. We finally show that the manner in which populations diverge has very little effect on the quality of reproductive isolation that evolves between them.