Hybridization in brushfinches (Atlapetes, Emberizidae) from the southeast Andes of Colombia: a consequence of habitat disturbance?

Hybridization between Atlapetes brushfinches has been scarcely documented across the 28 species of the genus. An unusual Atlapetes was observed and collected in the foothills of the southeast Andes of Colombia. We analysed plumage, morphometrics and mitochondrial and nuclear DNA sequences to test whether this specimen represented a hybrid or an aberrant individual of a local species. We found genetic and morphological evidence that the specimen is a hybrid between White-naped Brushfinch Atlapetes albinucha and Dusky-headed Brushfinch Atlapetes fuscoolivaceus . Phylogenetic analyses based on mitochondrial DNA suggest that its female parent was A. fuscoolivaceus , whereas nuclear DNA suggests that A. albinucha is likely the male parent. Moreover, the hybrid exhibits a combination of plumage characters of both parents, although morphometrically it is more similar to the male parent. We hypothesize that hybridization was likely facilitated by forest clearance enabling geographic contact between individuals of these species, which presumably were formerly isolated on different mountain slopes.