Phylogeny, diversity, and classification of the Accipitridae based on DNA sequences of the RAG-1 exon

The avian family Accipitridae has historically been divided into subfamilies or tribes based on features such as general resemblance, feeding ecology, and behavior. Consequently, the monophyly of those groups has been questionable. Recently, three phylogenetic analyses of a majority of the genera have appeared, one based on osteology, one on DNA sequences from a single mitochondrial gene, and the third on mitochondrial plus nuclear DNA sequences, and the resulting phylogenies were in substantial disagreement concerning the composition and basal branching patterns of the clades and hence require further analysis and confirmation. Here we use DNA sequences from the large nuclear RAG-1 exon to investigate the phylogenetic relationships of these birds. Our results largely corroborated the prior study that included nuclear genes. We found strong support for a monophyletic clade comprising the secretarybird Sagittarius serpentarius, the osprey Pandion haliaetus, and the traditional accipitrids. However, every one of the traditionally recognized subfamilies of accipitrids was found to be polyphyletic. The most basal nodes in the phylogeny separate small clades of insectivorous and scavenger species, such as kites and Old World vultures, from the rest of the family. The speciose genera of bird and mammal predators are all relatively derived (terminal) in the phylogeny. Many of the basal clades are cosmopolitan in their distributions, consistent with the great mobility of these raptors. A new classification is proposed that eliminates the problem of polyphyletic intrafamilial taxa.