DNA barcoding reveals recent speciation, extreme genus-level polyphyly and cryptic species in neotropical birds

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

Adelaida

Congreso; Fourth International Barcode of Life Conference; 2011

Consortium for the Barcode of Life y University of Adelaide

Wide scale DNA Barcoding projects provide the opportunity to conduct a standardized mitochondrial survey that can rapidly flag species or groups of species worthy of deeper study. Here we present three study cases that were originally identified while conducting Barcoding of Neotropical birds and led to multi-gene phylogenetic or phylogeographic analyses. COI haplotype sharing between 9 species of Sporophila seedeaters resulted in this group being the largest assemblage of bird taxa that could not be identified using DNA Barcodes. Further work including other mitochondrial markers, various nuclear introns and DNA microsatellite loci confirmed the extremely shallow divergence between these taxa, contrasting with the striking phenotypic differences observed in plumage and song. This pattern is consistent with the group undergoing a rapid and recent radiation during the Pleistocene, leaving signatures of demographic expansions, incomplete lineage sorting, and introgressive hybridization in their genes. COI patterns in the Andean-specialist genusPhrygilus suggested this group could be polyphyletic, with representatives of various other genera interspersed between them. This result was confirmed with other mitochondrial and nuclear markers, leading to the first phylogenetic hypothesis of the genus and suggesting it is composed of 4 distantly related clades that coincide with groups previously established mainly on the basis of plumage characters. Finally, DNA barcodes from passerines of the Malvinas/Falkland islands in the Southern Atlantic revealed deep divergence between the endemic Troglodytes cobbi and continentalTroglodytes aedon populations, two species involved in a long-standing taxonomic debate, that are currently still considered to be part of the same taxa. Further study using other nuclear and mitochondrial loci as well as song analysis suggests that T. cobbi may in fact deserve species status. As the project to barcode the birds of the world advances, many other cases of interest to evolutionary biologists will undoubtedly be revealed.