Speciation and secondary contact in a colourful agamid, Ctenophorus decresii

Abstract

Colour polymorphism, the co-existence of multiple heritable colour morphs within an interbreeding population, is thought to promote rapid phenotypic evolution and speciation. This is based on the importance of colour signals in reproductive isolation in combination with the underlying genetic architecture of polymorphism, where morphs are predicted to be governed by few genes of major effect. This prediction is supported by empirical data and stems from how colour morphs often differ in suites of co-adapted traits. During secondary contact between populations that differ in morphs, there is expected to be a high probability of genetic incompatibilities between morphs due to a breakdown of ad..