Range expansions of sexual versus asexual organisms: Effects of reproductive assurance and migration load

It is generally considered that sexual organisms show faster evolutionary adaptation than asexual organisms because sexuals can accumulate adaptive mutations through recombination. Yet empirical evidence often shows that the geographic range size of sexual species is narrower than that of closely-related asexual species, which may seem as if asexuals can adapt to more varied environments. Two potential explanations for this apparent contradiction considered by existing theory are reproduction assurance and migration load. Here, we consider both reproductive assurance and migration load within a single model to comparatively examine their effects on range expansions of sexuals and asexuals across an environmental gradient. The model shows that higher dispersal propensity decreases sexuals’ disadvantage in reproductive assurance while increasing their disadvantage in migration load. Moreover, lower mutation rate constrains adaptation more strongly in asexuals than in sexuals. Thus, high d..., We develop this computer simulation model., JDK 1.8