Molecular systematics of the caracaras and allies (Falconidae: Polyborinae) inferred from mitochondrial and nuclear sequence data

Abstract

The Polyborinae is the most diverse subfamily of the Falconidae in terms of both morphology and behaviour, and includes falconet‐shaped birds (Spiziapteryx), arboreal omnivores (Daptrius, Ibycter), as well as terrestrial generalists and scavengers (Caracara, Milvago and Phalcoboenus). The Polyborinae are endemic to the New World, with all but one species (Caracara cheriway) being restricted to Central and South America. Using over 7300 bp of mitochondrial and nuclear sequence data, we aim to clarify the taxonomy and biogeography of the Polyborinae. The genus Milvago was unexpectedly found to be polyphyletic, with Chimango Caracara Milvago chimango being related to the genus Phalcoboenus and Yellow‐headed Caracara Milvago chimachima being sister to Daptrius. Furthermore, very low genetic divergence was found among the four species of the genus Phalcoboenus, with the lowest divergence being between White‐throated Caracara Phalcoboenus albogularis and Mountain Caracara Phalcoboenus megalopterus. Our divergence time analyses revealed that the Polyborinae started to diversify in the Miocene, at about 14 Ma, and that the generalist/scavenger behaviour in the Falconidae appeared between 14 and 6.6 Ma. All speciation events within the caracaras occurred during the Pleistocene. This situation differs from the general pattern described for forest birds, in which most diversification events are older, occurring primarily in the Pliocene and Miocene.