Phylogeography and diversification of Oriental weaverbirds (Ploceus spp.): A gradual increase of eurytopy

Abstract

Weaverbirds are a speciose group of colorful passerines inhabiting the Old World Tropics. Nevertheless, the Oriental weaverbirds (Ploceus spp.), widespread across southern Asia, are much less diverse and restricted to a few ecological niches compared to their African counterpart. To investigate their phylogeography, we retrieved 101 samples of Baya Weaver (P. philippinus), Streaked Weaver (P. manyar), Black-Throated Weaver (P. benghalensis) and Asian Golden Weaver (P. hypoxanthus) along with GenBank sequences of Finn's Weaver (P. megarhynchus). We reconstructed the first molecular phylogeny based on a dataset consisting of both mitochondrial and nuclear genes, dating the most recent common ancestor of Oriental Ploceus to ∼11 mya. Subsequent speciation appears to have been a combination of divergence within the Indian subcontinent and dispersal across a barrier situated between the Indian subcontinent and the Indochinese region, which provided habitats with a varying degree of isolations and ultimately promoted divergences in allopatry. Two descendants of the earliest nodes, P. megarhynchus and P. hypoxanthus, are both rare and local, often found near large river systems, which perhaps reflects niche conservatism and a lack of adaptive potential. The three smaller species are all widespread, common and less habitat specific. The most recent divergence, between western and eastern P. philippinus populations, is supported by both phylogenetic and morphological evidence, pointing toward limited gene flow between them. However, a zone of intergradation may exist in Myanmar and Brahmaputra flood plains, thus preventing a recommendation for species level recognition without further study.