Evolutionary relationships and biogeography of the enigmatic West Indian butterfly genus Calisto, a high-throughput sequencing approach

The West Indies are an archipelago in the Atlantic Ocean, near the centre of America. The West Indies consist of the Greater Antilles, the Lesser Antilles and the Bahamas in the north. Due to its geological complexity, the region is considered a natural laboratory for the study of speciation, adaptive radiation and niche occupation. While many plant groups are highly diverse, most animal groups inhabiting the nearby continent are impoverished or completely absent on the islands, including good dispersal species such as insects, birds and bats.

Butterflies have not been spared from this situation either, as their fauna is rather sparse compared to the neighbouring continental areas and many tribes and butterfly subfamilies are missing or underrepresented. Calisto has experienced the greatest spread of all West Indian butterflies. The genus is endemic to the islands, where it is the only representative of the Satyrinae (Nymphalidae). There are 52 known species of Calisto, most of which are endemic to a single island or even a single mountain range. The generic affiliations remain unclear and it is estimated that the species appears to have been isolated since the Eocene. Given its apparently ancient origin, some authors have surmised that Calisto's ancestor may have reached the Proto-Antilles via GAARlandia, a land peninsula that connected northern South America to the islands 32-35 million years ago.

This project will re-examine the relationships of Calisto species using, for the first time, a high-throughput sequencing approach and sampling that includes nearly all species and many genera within their parent lineage, the highly diverse subgroup Satyrini. A biogeographical analysis will be conducted to determine the most likely place of origin of the generic ancestor. As the islands have been repeatedly flooded since the Pliocene, mountains probably played an important role in the survival and diversification of Calisto. For this reason, and due to the fact that most species are restricted to single mountain ranges or specific island areas, further biogeographical analysis using an island-within-island approach would shed light on how members of each species group evolved within the genus. The project will also revise the taxonomy of Calisto species, especially rare taxa known only from the types and cryptic, undescribed species, using current approaches developed for phylogenomics, wing pattern recognition and geometric morphometrics.