Habitat-driven diversification, hybridization and cryptic diversity in the Fork- tailed Drongo (Passeriformes: Dicruridae: Dicrurus adsimilis)

Species complexes of widespread African vertebrates that include taxa distributed across different habitats are poorly understood in terms of their phylogenetic rela-tionships, levels of genetic differentiation and diversification dynamics. The Fork- tailed Drongo (Dicrurus adsimilis) species complex includes seven Afrotropical taxa with parapatric distributions, each inhabiting a particular bioregion. Various taxo-nomic hypotheses concerning the species limits of the Fork- tailed Drongo have been suggested, based largely on mantle and upperpart coloration, but our understanding of diversity and diversification patterns remains incomplete. Especially given our lack of knowledge about how well these characters reflect taxonomy in a morpho-logically conservative group. Using a thorough sampling across Afrotropical biore-gions, we suggest that the number of recognized species within the D. adsimilis superspecies complex has likely been underestimated and that mantle and upperpart coloration reflects local adaptation to different habitat structure, rather than phyloge-netic relationships. Our results are consistent with recent phylogeographic studies of sub- Saharan African vertebrates, indicating that widespread and often morphologi-cally uniform species comprise several paraphyletic lineages, often with one or more of the lineages being closely related to phenotypically distinct forms inhabiting a different, yet geographically close, biome.