New world nine-primaried oscine relationships: Constructing a mitochondrial DNA framework

Historically, a paucity of comparative morphological characters has led to much debate regarding relationships within and among the major lineages of New World nine-primaried oscines. More recently, DNA-DNA hybridization stud ies have provided novel and testable hypotheses of relationships, although no consensus has been reached. For 40 songbird taxa, we obtained 1,929 base pairs (bp) of DNA sequence from the mitochondrial cytochrome-b (894 bp) an d NADH dehydrogenase subunit 2 (1,035 bp) genes. Phylogenetic analyses conf irm the monophyly of this assemblage as traditionally defined. The lineages delineated historically on morphological grounds are retained; finches (Fr ingillinae) are sister to a well-supported clade (Emberizinae) containing b lackbirds (Icterini), sparrows (Emberizini), wood-warblers (Parulini), tana gers (Thraupini), and cardinal-grosbeaks (Cardinalini). However, each tribe individually is either paraphyletic or polyphyletic with respect to most r ecent songbird classifications. Our results suggest that Euphonia is not a tanager but perhaps represents a derived form of cardueline finch. Piranga, traditionally considered a typical tanager, is a cardinaline in all of our analyses. Calcarius falls outside the sparrow lineage in all of our analys es, but its true affinities remain unclear. Elements of four different AOU families are represented in our clade Thraupini. The inclusion of several " tanager-finches" (Haplospiza, Diglossa, Tiaris, Volatinia, Sporophila) and a nectarivore (Coereba) in this dade is consistent with findings from other molecular phylogenies in suggesting that convergence in feeding specializa tions among some lineages has confounded traditional morphological classifi cations. We obtained a novel arrangement of relationships among tribes in o ur "best" topology; Cardinalini is sister to the rest of the Emberizinae as semblage las defined by Sibley and Ahlquist [1990]), and Thraupini is siste r to a clade containing Icterini, Emberizini, and Parulini. Despite nearly 2,000 bp of sequence for each taxon, and a high degree of stability across most weighting schemes and analytical methods, most nodes lack strong boots trap support. The ND2 gene provided higher resolution than did cytochrome b , but combining genes provided the most highly supported and resolved topol ogy. We consider the phylogeny a working hypothesis to be used as a guide f or further studies within the nine-primaried oscine assemblage.