Flickers of speciation: Sympatric colour morphs of the arc-eye hawkfish, Paracirrhites arcatus, reveal key elements of divergence with gene flow.

Abstract

One of the primary challenges of evolutionary research is to identify ecological factors that favour reproductive isolation. Therefore, studying partially isolated taxa has the potential to provide novel insight into the mechanisms of evolutionary divergence. Our study utilizes an adaptive colour polymorphism in the arc-eye hawkfish (Paracirrhites arcatus) to explore the evolution of reproductive barriers in the absence of geographic isolation. Dark and light morphs are ecologically partitioned into basaltic and coral microhabitats a few metres apart. To test whether ecological barriers have reduced gene flow among dark and light phenotypes, we evaluated genetic variation at 30 microsatellit..