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The complete mitochondrial DNA sequence of the shark Mustelus manazo: evaluating rooting contradictions to living bony vertebrates 总被引:5,自引:0,他引:5
A remarkable example of a misleading mitochondrial protein tree is
presented, involving ray-finned fishes, coelacanths, lungfishes, and
tetrapods, with sea lampreys as an outgroup. In previous molecular
phylogenetic studies on the origin of tetrapods, ray-finned fishes have
been assumed as an outgroup to the tetrapod/lungfish/coelacanth clade, an
assumption supported by morphological evidence. Standard methods of
molecular phylogenetics applied to the protein-encoding genes of
mitochondria, however, give a bizarre tree in which lamprey groups with
lungfish and, therefore, ray-finned fishes are not the outgroup to a
tetrapod/lungfish/coelacanth clade. All of the dozens of published
phylogenetic methods, including every possible modification to maximum
likelihood known to us (such as inclusion of site heterogeneity and
exclusion of potentially misleading hydrophobic amino acids), fail to place
the ray-finned fishes in a biologically acceptable position. A likely cause
of this failure may be the use of an inappropriate outgroup. Accordingly,
we have determined the complete mitochondrial DNA sequence from the shark,
Mustelus manazo, which we have used as an alternative and more proximal
outgroup than the lamprey. Using sharks as the outgroup, lungfish appear to
be the closest living relative of tetrapods, although the possibility of a
lungfish/coelacanth clade being the sister group of tetrapods cannot be
excluded.
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73.
Decomposable graphical Gaussian model determination 总被引:8,自引:0,他引:8