Museum phylogenomics of extinct Oryctes beetles from the Mascarene Islands

The evolution of island systems is characterized by processes that result in extreme morphological diversity, high endemism and high extinction rates. These dynamics can make phylogenetic reconstruction difficult, i.e. the extinct flightless Dodo from Mauritius was assigned to the family of doves only through DNA analysis of subfossils. Many insect species on islands have gone extinct through habitat loss, and face similar challenges to decipher their evolutionary history, however historical specimens have not yet been harnessed for phylogenomic reconstructions. Here, we employed historical museum specimens from the Mascarene Islands to generate the first whole-genome based phylogeny of three presumably extinct species of the rhinoceros beetle genus . We compared their genomes with those of an extant species from the island of Réunion, as well as a flightless Réunion-based species previously placed into the supposedly unrelated genus . We found that belongs instead to the genus and that the two Réunion-based species ( and ) are not sister taxa, suggesting two independent colonizations. The divergence time between them (<3Myr) overlaps with the volcanic formation of Réunion, likely indicating that became flightless . Our study showcases the power of genomes from insect museum specimens to address evolutionary questions in light of increasing extinction rates.