CONICET | Buscador de Institutos y Recursos Humanos

Background: The ultramarine grosbeak (Cyanocompsa brissonii) is a songbird of the Cardinalidae family exclusive to South America. It is divided into five subspecies, based on morphology and plumage coloration. A regional scale study of DNA barcodes showed that there are 2 clades of C. brissonii in Argentina, with more than 2% genetic divergence and no apparent geographical barriers that could impede the gene flow between them. Here, we analyzed variation in COI as well as in other mitochondrial and nuclear markers and assessed if phenotypic variation (morphology, plumage coloration and vocalizations) correlated with genetic variation. Results: We found two reciprocally monophyletic mitochondrial clades with high to maximum support within C. brissonii. Congruent with previous findings, clade 1 grouped individuals from northwestern Argentina, western Paraguay and Bolivia, while clade 2 included samples from northeastern Argentina, Brazil and Colombia. Mean divergence between clades was 2.43%, while average distance within them was 0.15% (clade 1) and 0.51% (clade 2). No distinguishable clades were found using nuclear markers. In Corrientes province (Argentina) both clades meet, and the area where individuals of both clades can be found extends at least from the Parana River to the Mburucuya National Park (approximately 50 km). Individuals from this area could not always be assigned correctly to their genetic clade based on their phenotype, contrary to what happened with individuals from other regions. Significance: It has recently been estimated that the actual number of bird species might be twice than currently recognized. The correct delimitation and quantification of species is fundamental for evolutionary studies and conservation efforts. This study shows that DNA barcodes can play a fundamental role in detecting cryptic diversity and assessing species boundaries. It is worth mentioning that this is the first time individuals from the isolated population of Colombia are included in molecular analyses.