Acoustic, genetic, and morphological analyses of the Canarian common chaffinch complex Fringilla coelebs ssp. reveals cryptic diversification

The common chaffinch Fringilla coelebs is the extant avian species with the highest level of differentiation across North Atlantic archipelagos. Such a degree of diversification has been traditionally recognised within the subspecies category, with one endemic subspecies occurring in Azores (F. c. moreletti), one in Madeira (F. c. maderensis), and three in the Canary Islands (F. c. canariensis, F. c. palmae and F. c. ombriosa). Recent genetic, acoustic, and sperm morphology studies informed us about the significant differentiation of the Gran Canaria population, which is traditionally included within F. c. canariensis subspecies. The goal of this study is to examine the similarity of the Canarian chaffinches, with the objective of determining if the Gran Canaria chaffinches represent an isolated and distinct population. In order to achieve this aim, we used a double approach: 1) we analysed new morphological and genetic data from the Canary Islands, and 2) we reviewed and synthesised the vast acoustic, morphological and genetic information available for these taxa in Macaronesia, with special emphasis on the Canary Islands. Genetic, acoustic, and sperm morphological data, and to a lesser extent phenotypic data, strongly support the existence of a cryptic taxon in Gran Canaria. Moreover, our findings also reveal an incipient speciation process on going in the Canary Islands, mostly driven by genetic differentiation. Overall, our synthesis suggests that individuals occurring in Gran Canaria should be considered as a novel taxon that we formally described as Fringilla coelebs bakeri ssp. nov.