A molecular phylogeny of warbling-finches (Poospiza): Paraphyly in a neotropical emberizid genus

We investigated the phylogenetic relationships of 12 species within a singl e genus of neotropical passerine (Poospiza) using 849 bp (283 codons) of th e cytochrome b mitochondrial gene. We further explored evolutionary affinit ies of these tars using sequence from an additional 47 thraupine (tanagers) and 7 emberizine (sparrows and buntings) genera, members of the predominan tly New World family Emberizidae. Poospiza have traditionally been consider ed part of the emberizine radiation. However, our analyses suggest that mem bers of this genus are more closely related to some thraupine lineages than they are to the other neotropical emberizine genera included in our study (Atlapetes, Embernagra, Melopyrrha, Phrygilus, Saltatricula, Tiaris). Altho ugh member taxa are closely related, the genus Poospiza appears to be parap hyletic with representatives of 6 thraupine genera (Cnemoscapus, Cypsnagra, Hemispingus, Nephelornis, Pyrrhocoma, Thylpopsis) interspersed among four well-supported Poospiza clades. The majority of species within this Poospiz a-thraupine clade have geographic ranges that are exclusive to, or partiall y overlap with, the Andes Mountains. It is probable that these mountains ha ve played an important role in driving cladogenesis within this group. Sequ ence divergence (transversions only; mean 4.1 +/- 1.3%) within the clade su ggests that much of this diversification occurred within the late Miocene a nd Pliocene, a period coincident with major orogenic activity in central-we stern South America. (C) 2000 Academic Press.