Afrotropics on the wing: phylogenomics and historical biogeography of awl and policeman skippers

摘要

The Old-World Tropics encompass many unique biomes and associated biotas shaped by drastic climate and geological changes throughout the Cenozoic. Disjunct distributions of clades between the Afrotropics and the Oriental regions are testament to these changes. Awl and policeman skippers (Hesperiidae: Coeliadinae) are disjunctly distributed with some genera endemic to the Afrotropics and others restricted to the Oriental and Australian regions. We reconstruct the phylogeny of these butterflies using target exon capture phylogenomics. We also generate a dated framework for this clade that uses the putatively oldest known butterfly fossil to estimate the historical biogeography of Coeliadinae using a model-based approach. We infer a stable and robust phylogeny for the subfamily, with all but one Afrotropical lineage forming a derived clade. The African genusPyrrhiadessyn. nov.is placed in synonymy withCoeliadesto accommodate the new phylogeny. Our comparative dating exercise casts doubt on the assignment of the fossilProtocoeliades kristensenias a derived Coeliadinae and suggests, along with our biogeographic estimation, a split of Coeliadinae from the rest of skippers in the Palaeoceneca. 70 million years ago. The origin of crown Coeliadinae skippers is estimated in Indomalaya during the late Eoceneca. 36 million years ago, with subsequent Oligocene colonisation events toward the Australian region and the Afrotropics. Colonisation of the Afrotropics from the Indian region occurred during climatic transition, associated biome shifts, and the closure of the Tethys Ocean, which likely allowed geodispersal through the Arabian Peninsula. The current disjunct distribution of Coeliadinae in the Old World Tropics may result from the emergence of savannahs in the Miocene that progressively replaced woodlands and forests in the Arabian Peninsula and western Asia. Coeliadinae skippers are almost exclusively dicot feeders and were likely extirpated as grasslands became dominant, resulting in the present-day disjunct distribution of these butterflies.