SRA

Biologists marvel at the powers of adaptive convergence, when distantly related animals look alike. While mimetic wing patterns of butterflies have fooled predators for millennia, entomologists inferred that mimics were distant relatives despite similar appearance. However, the obverse question has not been frequently asked. Who are the close relatives of mimetic butterflies and what are their features? As opposed to close convergence, divergence from a non-mimetic relative would also be extreme. When closely related animals look unalike, it is challenging to pair them. Genomic analysis promises to elucidate evolutionary relationships and shed light on molecular mechanisms of divergence. We chose the Firetip skipper butterflies as a model due to their phenotypic diversity and abundance of mimicry. We sequenced and analyzed whole genomes of nearly 120 representative species. Genomes partitioned this subfamily Pyrrhopyginae into 5 tribes (1 new), 23 genera and, additionally, 22 subgenera (10 new). The largest tribe Pyrrhopygini is divided into 4 subtribes (3 new). Surprisingly, we found 5 cases where a uniquely patterned butterfly was formerly placed in a genus of its own and separately from its close relatives. In several cases, extreme phenotypic and rapid divergence involved not only wing patterns but also the structure of the male genitalia. The visually striking wing pattern difference between close relatives frequently involves disappearance or suffusion of spots and color exchange between orange and blue. These differences, in particular a transition between unspotted black and striped wings, happen recurrently on a short evolutionary time-scale, and are therefore likely achieved by only few mutations.