Batesian mimicry promotes pre- and postmating isolation in a snake mimicry complex

Area of Science:

• Evolutionary Biology
• Ecology
• Behavioral Ecology

Background:

• Batesian mimicry involves a palatable species (mimic) evolving to resemble an unpalatable species (model).
• Mimics and models often coexist (sympatry), but mimics can also be found without their models (allopatry).
• Local adaptation in sympatry and allopatry may lead to divergent selection pressures.

Purpose of the Study:

• To investigate if Batesian mimicry contributes to early-stage reproductive isolation.
• To determine if predator-mediated selection favors local phenotypes over immigrants and hybrids.

Main Methods:

• Clay replicas of sympatric, allopatric, and hybrid snake phenotypes were used.
• Replicas were placed in both sympatric and allopatric environments.
• Predation attempts on replicas were measured to infer selection pressures.

Main Results:

• Immigrant phenotypes (allopatric in sympatry, sympatric in allopatry) experienced higher predation.
• Hybrid phenotypes faced selection against them, particularly in sympatric areas with strong mimicry selection.
• Predator-mediated selection disfavored both immigrant and hybrid phenotypes.

Conclusions:

• Batesian mimicry can promote reproductive isolation by increasing immigrant inviability.
• Ecologically dependent selection against hybrids, driven by mimicry, may contribute to divergent evolution.
• Mimicry may play a significant role in speciation, beyond its role in convergent evolution.