Molecular systematics of the grackles and allies, and the effect of additional sequence (cyt b and ND2)

Within the New World blackbirds, the lineage of grackles and their allies contains several species that have been extremely well studied by avian biologists. Using mitochondrial DNA (mtDNA) sequences, we present a phylogeny for the grackles and allies that serves as a basis for comparative studies in this group. We compare two gene regions and determine that ND2 is evolving more rapidly than cytochrome b. However, this difference in evolutionary rate does not result in significant incongruence between phylogenies derived from the two gene regions independently A combined weighted analysis provides a completely resolved phylogeny for this group. In general, this phylogeny has higher support than the phylogenies derived from the two genes independently. Two major clades are identified in this combined phylogeny (1) a completely South American clade, and (2) a largely North American/Caribbean/Central American clade. This phylogeny has important implications for the study of behaviors and morphology.