Hybridization constrains the evolution of mimicry complexes in woodpeckers

Abstract

The evolution of interspecific mimicry does not always result in perfect resemblance between mimics and models. Differences between members of a mimicry complex can be explained by genetic or developmental constraints. Alternatively, imperfect mimicry might be the outcome of a tradeoff between multiple selective pressures. In this study, we explored the evolutionary conflict between mimicry and hybridization in woodpeckers. Based on the selective tradeoff hypothesis, we expected that mimicry complexes will start to evolve once the constraint of maladaptive hybridization is relaxed. Hence, we predicted limited overlap in the divergence times between hybridizing species pairs and members of a mimicry complex. This prediction was supported by clear tipping point in the probability of hybridization and mimicry at ca 9 million years of divergence. Around this timepoint, the probability of hybridization approaches zero while the probability of belonging to a mimicry complex increases. This finding is only correlational and remains to be confirmed in other taxonomic groups. Nonetheless, our results suggest a selective tradeoff between evolving interspecific mimicry and avoiding maladaptive hybridization in woodpeckers.