Novel insights into the historical biogeography of the streak-breasted scimitar babbler complex (Aves: Timaliidae: Pomatorhinus ruficollis complex)

Abstract

The Streak-breasted Scimitar Babblers of the Pomatorhinus ruficollis species complex are found in most of the forested habitats across southern and eastern Asia. The diversification history of this group is obscured by high plumage variation across populations and conflicting genetic signal across loci. We combined genetic and geographic data from several recent studies to investigate how these species diversified across China using both phylogenetic and ecological niche modeling analyses. These two lines of evidence are consistent in showing that two well-sampled species, P. reconditus and P. nigrostellatus, in central and southern China respectively, likely experienced a history of isolation and expansion as suitable habitat contracted during the last interglacial and expanded in patchy extent during the glacial maximum. The genetic analysis showed that populations of P. nigrostellatus on Hainan Island are very similar to the ones in nearby mainland southern China. We recovered two well-supported clades within P. reconditus that were not geographically structured with both containing individuals from the same localities across central China. This phylogenetic result corresponded to the ecological niche models that showed expansion from refugia since the last interglacial. This study illustrates the value of using an integrative approach and detailed geographic sampling to help understand the recent diversification of birds in China.