STRONG NATURAL SELECTION IN A WARNING-COLOR HYBRID ZONE

Strong Natural Selection in a Warning-color Hybrid Zone.

Frequency-dependent selection on warning color can maintain narrow hybrid zones between unpalatable prey taxa. To measure such selection, we transferred marked Heliconius erato (Lepidoptera: Nymphalidae) in both directions across a 10-km-wide hybrid zone between Peruvian races differing in color pattern. These experimental H. erato were released at four sites, along with control H. erato of the...

Strong natural selection on juveniles maintains a narrow adult hybrid zone in a broadcast spawner.

Natural selection can maintain and help form species across different habitats, even when dispersal is high. Selection against inferior migrants (immigrant inviability) acts when locally adapted populations suffer high mortality on dispersal to unsuitable habitats. Habitat-specific populations undergoing divergent selection via immigrant inviability should thus show (1) a change in the ratio of...

Natural and Sexual Selection in a Natural Hybrid Zone of Ficedula Flycatchers

Sexual selection against natural hybrids may contribute to reinforcement in a house mouse hybrid zone.

Sexual selection may hinder gene flow across contact zones when hybrid recognition signals are discriminated against. We tested this hypothesis in a unimodal hybrid zone between Mus musculus musculus and Mus musculus domesticus where a pattern of reinforcement was described and lower hybrid fitness documented. We presented mice from the border of the hybrid zone with a choice between opposite s...

Strong Amplifiers of Natural Selection: Proofs

We consider the modified Moran process on graphs to study the spread of genetic and cultural mutations on structured populations. An initial mutant arises either spontaneously (aka uniform initialization), or during reproduction (aka temperature initialization) in a population of n individuals, and has a fixed fitness advantage r > 1 over the residents of the population. The fixation probabilit...