Browsing by Subject "Taxa"
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Item A Molecular Phylogeny of the Blackbirds (Icteridae): Five Lineages Revealed by Cytochrome-B Sequence Data(American Ornithological Society, 1999-07) Lanyon, Scott M.; Omland, Kevin E.New World blackbirds (Icteridae) have long served as model systems for studies of avian ecology, evolution, and behavior. However, this work has been conducted in the absence of a strong phylogenetic hypothesis for the group. We sequenced 890 base pairs (bp) of the mitochondrial cytochrome-b gene for 28 of the 29 icterid genera and subgenera recognized by Blake (1968). We found strong evidence of five lineages of blackbirds: grackles and allies; caciques and oropendolas; orioles; meadowlarks and allies; and a monotypic cupnesting cacique lineage. However, we found little support for any further structure among these five lineages and no strong evidence supporting icterid monophyly. Our results set the stage for forthcoming work on relationships within lineages and for higher-level studies that address blackbird monophyly and relationships among lineages.Item Novel Intron Phylogeny Supports Plumage Convergence in Orioles (Icterus)(American Ornithological Society, 2003-10) Allen, Eva Sanders; Omland, Kevin E.A recent study of New World orioles (Icterus spp.), which traced a large number of plumage characters onto a mitochondrial DNA phylogeny, reported high frequencies of evolutionary convergence and reversal of plumage characters (Omland and Lanyon 2000). Although those results are consistent with other smaller scale studies that have documented plumage homoplasy, the mitochondrial genome is inherited as a single linkage group, so mitochondrial data represent only one gene tree. The mitochondrial (mt) DNA tree may not reflect the true evolutionary history of a lineage; therefore, it remains possible that the plumage characters could reflect the true species phylogeny. Other rapidly evolving regions of DNA can provide independent phylogenetic hypotheses useful for evaluating mitochondrial gene trees. A novel phylogenetic marker, a region of the nuclear gene ornithine decarboxylase (ODC) spanning from exon 6 to exon 8, was sequenced in 10 oriole species. The resultant nuclear gene tree reconstructs the same three major oriole clades as the mtDNA tree (Omland et al. 1999), supporting the conclusion that plumage evolution in the New World orioles has been highly homoplastic. Although most phylogenetic studies that have employed introns report greatest resolution at the genus or family level, ODC appears to offer some degree of phylogenetic resolution for infrageneric analyses. However, that intron has clearly not sorted to monophyly within or between closely related species.