Peering into the past and predicting the future of the threatened southern swallowtail, <i>Papilio alexanor</i> Esper, 1799 (Lepidoptera: Papilionidae)

Abstract We investigated the evolutionary history of the threatened southern swallowtail butterfly (Papilio alexanor) using DNA sequences from COI barcodes, in addition to two nuclear genes (EF-1a and wingless) for a subset of the samples and outgroups to strengthen the backbone of the phylogeny. Our results align with previous hypotheses on the origin of this species in the eastern Palaearctic and clarify its current systematics by delineating five subspecies-level clades. Accordingly, we reinstate P. alexanor ssp. voldemar stat. rev. as a valid subspecies. Our phylogeographical analysis shows that P. alexanor is likely to have originated in Central Asia in the Eocene and began diversification and dispersal towards the west in the Early Miocene, arriving in Europe ∼9 Mya. Results of our species distribution modelling analysis suggest that although suitable habitats for P. alexanor will be likely to persist in the eastern parts of its distribution range, the species will be extinct in 89% of its potential suitable habitat by 2070 owing to environmental changes. We show that a combination of molecular phylogenetics and species distribution modelling can be used to reconstruct the evolutionary history and simultaneously predict the persistence of a species into the future. Our results also underline the high sensitivity of species with restricted distributions in times of rapid climate change, which might even drive such taxa towards global extinction.