A comprehensive phylogeny of the nuthatches, genus Sitta, is proposed based on 21 of the 24-28 species recognized in the genus and three genes, two mitochondrial (cytochrome b and cytochrome oxidase subunit I) and one nuclear (RAG1). This phylogeny is well resolved and reveals several major clades within nuthatches. Przevalski's Nuthatch Sitta przewalskii is sister to all other nuthatches, without any close relatives in our sampling. The larger species S. carolinensis and S. magna, despite their disjunct distributions, are sister taxa at the base of the tree. The next clade comprises the europaea group, which is sister to the two rock nuthatches (S. tephronota and S. neumayer), and to the Beautiful Nuthatch Sitta formosa of southeast Asia, although with less support. All these species use plastering to reduce the entrance of their hole or to build their nest with mud on rocks, but their ecologies are not as specialized as those of the rock nuthatches. The Asian small species (represented by S. azurea, S. frontalis and S. oenochlamys) form a well-supported clade. We confirm a single origin for the canadensis group that also includes the Yunnan nuthatch Sitta yunnanensis. Both are sister group to the two sibling species of North America (S. pygmaea and S. pusilla); all these species dig their own nest in trunks and are closely associated with coniferous forest. A biogeographical analysis supports the hypothesis of Asia being the center of diversification for nuthatches, with several independent dispersal events to North America.
- Biogeographical analysis
- Mitochondrial and nuclear genes
- Nesting behavior
- Phylogenetic relationships