Phylogeography of the Delias hyparete species group (Lepidoptera: Pieridae): Complex historical dispersals into and out of Wallacea

Abstract

The unique and highly endemic fauna of Wallacea has been extensively examined; however, the diversification of a single animal lineage in Wallacea has not yet been studied in detail. The Delias hyparete (Linnaeus) species group is distributed in the Oriental and Australian regions as well as throughout Wallacea (i.e. North Maluku, South Maluku, Sulawesi and Lesser Sunda), with the highest species diversity occurring in Wallacea. The present study reconstructed the phylogeny and estimated the between- and within-species divergence of the D. hyparete group using two genes: mitochondrial NADH-dependent dehydrogenase subunit 5 (ND5) and nuclear elongation factor 1 alpha (EF1-α). Two out of five clades were associated with Lesser Sunda, and the remaining three clades were associated with North Maluku, South Maluku and Sulawesi, respectively. Ancestral area analyses and molecular dating suggested five colonization events into Wallacea at various times with the Australian and Oriental regions inferred as the geographical origins; Lesser Sunda may have been colonized twice. Two range expansion events from Lesser Sunda to Greater Sunda in the recent past and an older dispersal passing through Wallacea towards the Oriental region have also been inferred. The species diversity of this butterfly group in Wallacea appears to have developed due to non-sympatric speciation events. Complex historical dispersals into and out of Wallacea inferred in the D. hyparete group reinforce the view that animals move across Wallace’s and Lydekker’s Lines more frequently than classical assumptions, and these complex dispersals may have largely contributed to the high biodiversity and endemism evident in Wallacea.