Mitochondrial DNA Sequence Evolution in the Arctoidea

Some taxa in the superfamily Arctoidea, such as the giant panda and the lesser panda, have presented puzzles to taxonomists. In the present study, ≈ 397 bases of the cytochrome b gene, 364 bases of the 12S rRNA gene, and 74 bases of the tRNAThrand tRNAProgenes from the giant panda, lesser panda, kin...

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Published inProceedings of the National Academy of Sciences - PNAS Vol. 90; no. 20; pp. 9557 - 9561
Main Authors Zhang, Ya-Ping, Ryder, Oliver A.
Format Journal Article
LanguageEnglish
Published Washington, DC National Academy of Sciences of the United States of America 15.10.1993
National Acad Sciences
National Academy of Sciences
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Summary:Some taxa in the superfamily Arctoidea, such as the giant panda and the lesser panda, have presented puzzles to taxonomists. In the present study, ≈ 397 bases of the cytochrome b gene, 364 bases of the 12S rRNA gene, and 74 bases of the tRNAThrand tRNAProgenes from the giant panda, lesser panda, kinkajou, raccoon, coatimundi, and all species of the Ursidae were sequenced. The high transition/transversion ratios in cytochrome b and RNA genes prior to saturation suggest that the presumed transition bias may represent a trend for some mammalian lineages rather than strictly a primate phenomenon. Transversions in the 12S rRNA gene accumulate in arctoids at about half the rate reported for artiodactyls. Different arctoid lineages evolve at different rates: the kinkajou, a procyonid, evolves the fastest, 1.7-1.9 times faster than the slowest lineage that comprises the spectacled and polar bears. Generation-time effect can only partially explain the different rates of nucleotide substitution in arctoids. Our results based on parsimony analysis show that the giant panda is more closely related to bears than to the lesser panda; the lesser panda is neither closely related to bears nor to the New World procyonids. The kinkajou, raccoon, and coatimundi diverged from each other very early, even though they group together. The polar bear is closely related to the spectacled bear, and they began to diverge from a common mitochondrial ancestor ≈ 2 million years ago. Relationships of the remaining five bear species are derived.
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ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.90.20.9557