Dynamics and Phylogenetic Implications of MtDNA Control Region Sequences in New World Jays (Aves: Corvidae) |
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Authors: | Matthew A Saunders Scott V Edwards |
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Institution: | (1) Department of Zoology and Burke Museum, Box 351800, University of Washington, Seattle, WA 98195, USA, US |
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Abstract: | To study the evolution of mtDNA and the intergeneric relationships of New World Jays (Aves: Corvidae), we sequenced the entire
mitochondrial DNA control region (CR) from 21 species representing all genera of New World jays, an Old World jay, crows,
and a magpie. Using maximum likelihood methods, we found that both the transition/transversion ratio (κ) and among site rate
variation (α) were higher in flanking domains I and II than in the conserved central domain and that the frequency of indels
was highest in domain II. Estimates of κ and α were much more influenced by the density of taxon sampling than by alternative
optimal tree topologies. We implemented a successive approximation method incorporating these parameters into phylogenetic
analysis. In addition we compared our study in detail to a previous study using cytochrome b and morphology to examine the effect of taxon sampling, evolutionary rates of genes, and combined data on tree resolution.
We found that the particular weighting scheme used had no effect on tree topology and little effect on tree robustness. Taxon
sampling had a significant effect on tree robustness but little effect on the topology of the best tree. The CR data set differed
nonsignificantly from the tree derived from the cytochrome b/morphological data set primarily in the placement of the genus Gymnorhinus, which is near the base of the CR tree. However, contrary to conventional taxonomy, the CR data set suggested that blue and
black jays (Cyanocorax sensu lato) might be paraphyletic and that the brown jay Psilorhinus (=Cyanocorax) morio is the sister group to magpie jays (Calocitta), a phylogenetic hypothesis that is likely as parsimonious with regard to nonmolecular characters as monophyly of Cyanocorax. The CR tree also suggests that the common ancestor of NWJs was likely a cooperative breeder. Consistent with recent systematic
theory, our data suggest that DNA sequences with high substitution rates such as the CR may nonetheless be useful in reconstructing
relatively deep phylogenetic nodes in avian groups.
Received: 10 November 1999 / Accepted: 16 March 2000 |
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Keywords: | : Control region — Cooperative breeding — Corvidae — Among-site rate variation — Taxon sampling — Combined data — Psilorhinus morio |
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