The Nanling Mountains are an important mountain range and watershed in southcentral China. Because of the abundance in relictual plant species and geological stability throughout the Cenozoic, the mountains are considered a “museum” of subtropical biological diversity. With respect to birds, however, the roles of the Nanling Mountains in impeding the dispersal of the subtropical birds and, as a result, shaping their population and community structures have received little consideration. To examine these roles, we compiled and analyzed two datasets. (1) To test the mountains’ influence on gene flow, we undertook a population phylogeographic study comparing mitochondrial COI and Cytb DNA sequences of 5 sylvioid resident bird species of the mountains (Huet’s Fulvetta Alcippe hueti, Red-billed Leiothrix Leiothrix lutea, Greater Necklaced Laughingthrush Pterorhinus pectoralis, Indochinese Yuhina Staphida torqueola, and Mountain Bulbul Ixos mcclellandii). (2) To examine differentiated community development over the history of modern birds, we examined distributional data of all species of the Nanling region using public species occurrence records. For part (1), we sampled 327 individuals from 36 sites and conducted correlation analysis of genetic and geographic distances, taking into account the landscape of the mountains. We found that the mountains do not seriously impede gene flow among populations but influenced species differently. For part (2), comparative analysis of 446 species in 81 families indicated that family membership influenced the community composition of birds in Nanling region. Variation in family distributions is attributable to both environmental and evolutionary factors. Overall, we found that the Nanling Mountains are not currently a substantial barrier to gene flow among the species we studied but act as a corridor and refuge for these birds. However, analyses on higher ranked community data suggest the mountains acted as a barrier in older times, corresponding to the known diversification events in southeast Asian avifauna.
