Molecular systematics and diversification of the Asian scimitar babblers (Timaliidae, Aves) based on mitochondrial and nuclear DNA sequences

The Asian scimitar babblers, including the genus Pomatorhinus and Xiphirhynchus, are a small group of babblers characterized by long down-curved bills and a distribution throughout East and Southeast Asia. To infer the molecular phylogeny of this group and their divergence time, we examined sequences of multiple fragments including two entire mitochondrial genes and four nuclear introns (4352. bp in total) from multiple samples of eight of the nine recognized species of Asian scimitar babblers. The phylogeny resulting from the concatenated multi-locus dataset suggests that Pomatorhinus is paraphyletic. Due to its paraphyly, we propose dividing the traditional genus Pomatorhinus into two morphologically and genetically diagnosable genera: Pomatorhinus and Erythrogenys. Results of the molecular dating based on the conventional mitochondrial DNA divergence rate indicates that the diversification of these babblers is likely congruent with the historical climatic events. Our findings shed light on the diversification of avian species in southern Asia, a poorly studied biodiversity hotspot.