Mol. Phylogenet. Evol.

The frigatebirds (Fregatidae) and Tropicbirds (Phaethonidae) represent the most morphologically and behaviorally distinct members of the traditional Order Pelecaniformes. Using 1756bp of mitochondrial DNA sequence consisting of the 12S, ATPase-6, ATPase-8, and COI genes obtained from all extant species, we derive a completely resolved phylogeny for both groups. The inferred relationships among these species are robust to the method of phylogenetic estimation used, and all branches are well supported, in spite of the relatively recent radiation within the frigatebirds. The two families are not closely related either to each other, or to any other putative relatives (e.g., pelicans; Pelecanidae).

Source:http://purl.uniprot.org/citations/15019606