Evidencia genética de una radiación en el género Sporophila

CAMPAGNA, LEONARDO; LIJTMAER, DARÍO A.; LOUGHEED, STEPHEN C.; TUBARO, PABLO L.

Tafí del Valle

Congreso; XIII Reunión Argentina de Ornitología; 2009

Aves Argentinas - Asociación Ornitológica del Plata

The capuchinos are 11 Sporophila species with little morphological differentiation, extended sympatry, and a high degree of sexual dimorphism in both color patterns and vocalizations. Previous work from our group using mitochondrial DNA (partial cytochrome b and COII-Tlys-ATP8 fragment) suggested that the capuchinos are monophyletic and divided into two clades: northern capuchinos (2 species) and southern capuchinos (9 species). The phylogenetic relationships among the southern capuchinos were unresolved due to lack of reciprocal monophyly among species. The objective of this study was to clarify the phylogenetic relationships of the capuchinos by a) analyzing cytochrome c oxidase 1 (COI) variation and this gene’s ability to separate species in the group; b) extending the analysis to other rapidly evolving mitochondrial and nuclear markers. In total we sequenced 4.2 kb (cytochrome b, COI, mitochondrial control region and 2 nuclear pseudogenes: numt2 and numt3) and genotyped 191 samples for 6 microsatellite loci. We subjected the sequences to neighbour joining, maximum parsimony and Bayesian phylogenetic analyses and calculated the degree of differentiation between species using microsatellite allele frequencies. We found that the southern capuchinos share COI haplotypes and show extremely low interspecific divergence constituting the only example of several species that cannot be separated among the neotropical birds barcoded so far. No further insight into the phylogenetic relationships of the group was obtained with the remaining markers, suggesting that the lack of resolution using COI is due to the biology of the southern capuchinos rather than to limitations of this molecular marker. Our results flag the southern capuchinos as a new case of an explosive and recent radiation where incomplete lineage sorting and hybridization with introgression are the most likely causes for the observed genetic pattern.