Molecular phylogeny of Palearctic-African Acrocephalus and Hippolais Warblers (Aves: Sylviidae).

Phylogenetic relationships of the reed warbler group (genera Acrocephalus, Hippolais, Chloropeta; Aves: Passeriformes) and their potential relatives were studied using nucleotide sequences (1 kb) of the mitochondrial cytochrome b gene. This species-rich but morphologically poorly differentiated group of insectivorous passerines is distributed in Eurasia, Africa, and Australasia. Intergeneric relationships were poorly resolved, but monophyly of the reed warbler group (including Chloropeta) versus other Sylviidae was strongly supported. A basal polytomy within the reed warbler group consists of seven branches and may indicate a rapid early radiation. In the genus Acrocephalus three major clades were identified, which corresponded to phenotypic groups characterized by body size and plumage patterns. However, current delimitation of some subgenera (Acrocephalus, Lusciniola, Bebrornis) is at variance with our phylogeny estimate, and appropriate revisions are proposed. The genus Hippolais, which may or may not be monophyletic, consisted of two well-supported clades of four species each. Some Acrocephalus taxa whose species status had been doubted (griseldis, tangorum, orientalis, australis) proved to be highly distinct genetically. Genetic distances between members of two pairs of allopatric Hippolais taxa (caligata/rama; opaca/elaeica) were as large or larger than between other closely related warbler species. Overall, cytochrome b sequences resolved phylogenetically young relationships quite well, whereas more ancient nodes remained poorly resolved.