These wing patterns are also used in mate choice, and morph-based assortative mating can arise as a byproduct of selection for wing mimicry 14 if accompanied by evolution of preferences. In Heliconius, selection for Müllerian mimicry (mimicry between unpalatable species) has led to intraspecific divergence in wing patterns, as different populations radiate into distinct mimicry rings 13. This has led to impressive morphological radiations in diverse taxonomic groups such as catfish 7, millipedes 8, snakes 9, bees 10, frogs 11, moths 12 and, most famously, Heliconius butterflies 13. Mimicry can drive phenotypic convergence between distantly related species, but can also drive within-species diversification. With the goal of investigating initial divergence, one can focus on the early stages of speciation, for example, populations of a single species showing incipient reproductive isolation. However, these reproductive barriers may have arisen after speciation was complete, whereas other, currently incomplete barriers may have arisen earlier and been important during initial population divergence 6.
Speciation is frequently studied by examining pairs of ‘good’ species and identifying current reproductive barriers 5. Several studies have identified cases where divergent selection on ecologically relevant traits leads to partial or complete reproductive isolation or speciation 1, 2, 3, 4. These results extend the effects of mimicry on speciation into a vertebrate system and characterize an early stage of speciation where reproductive isolation between mimetic morphs is incomplete but evident.Įlucidating the factors that promote population divergence and initiate speciation is key to understanding the evolution of biodiversity.
imitator is associated with a narrow phenotypic transition zone, neutral genetic divergence and assortative mating, suggesting that divergent selection to resemble different model species has led to a breakdown in gene flow between these two populations. Using a combination of colour–pattern analysis, landscape genetics and mate-choice experiments, we show that a mimetic shift in R. We study the Peruvian poison frog Ranitomeya imitator, a species that has undergone a mimetic radiation into four distinct morphs. While mimetic radiations have occurred in a variety of taxa, their role in speciation remains poorly understood. In a mimetic radiation-when a single species evolves to resemble different model species-mimicry can drive within-species morphological diversification, and, potentially, speciation.
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