Rapid Radiation of Canaries (Genus Serinus)

Abstract

Mitochondrial cytochrome b (mit cyt b) DNA from 20 out of 37 extant canaries (genus Serinus) has been sequenced from living specimens photographed around the world. Phylogenetic analysis has consistently resulted in the same groupings of birds, which have generally been related to geographical proximity. The fossil registry of chicken and pheasant and its divergence time have been used to calibrate the molecular clock; mit cyt b DNA dendrograms suggest that the Serinus bird lineage appeared in the Miocene (9 MYA), a time when the Mediterranean Sea was closing its western and eastern oceanic connections. Pleistocene glaciations (starting 2 MYA) may have only been important in the subspeciation and isolation of birds in the Northern and Southern hemispheres around the world, and not only in North America, where it has already been described. The European-isolated Serinus citrinella (Citril finch) is not a canary but rather a true goldfinch. Only about 4% average nucleotide divergence is found among the different Serinus species; this suggests a remarkably rapid radiation when compared to other passerine (songbird) genera radiations. In addition, reproductive barriers are observed between closely related species but not between other more distant ones. Finally, a tentative classification for the genus Serinus species is put forward.