Liking the good guys: amplifying local adaptation via the evolution of condition-dependent mate choice

Local adaptation can be strengthened through a diversity of mechanisms that reduce gene flow between contrasting environments. Recent work revealed that mate choice could enhance local adaptation when females preferentially mate with locally adapted males and that such female preferences readily evolve, but the opposing effects of recombination, migration, and costs of female preferences remain relatively unexplored. To investigate these effects, we develop a two-patch model with two genes, one influencing an ecological trait and one influencing female preferences, where both male signals and female preferences are allowed to depend on the match between an individual's ecological trait and the local environment (condition). Because trait variation is limited when migration is rare and the benefits of preferential mating are short-lived when migration is frequent, we find that female preferences for males in high condition spread most rapidly with intermediate levels of migration. Surpri...