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Adaptive Evolution of5'HoxD Genes in theOrigin andDiversification ofthe Cetacean Flipper Zhe WangLiping YuanStephen J. Rossiter2008 год

Adaptive Evolution of 5'HoxD Genes in the Origin and Diversification of the Cetacean Flipper
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Аннотация: The homeobox (Hox) genes Hoxd12 and Hoxd13 control digit patterning and limb formation in tetrapods. Both show strong expression in the limb bud during embryonic development, are highly conserved across vertebrates, and show mutations that are associated with carpal, metacarpal, and phalangeal deformities. The most dramatic evolutionary reorganization of the mammalian limb has occurred in cetaceans (whales, dolphins, and porpoises), in which the hind limbs have been lost and the forelimbs have evolved into paddle-shaped flippers. We reconstructed the phylogeny of digit patterning in mammals and inferred that digit number has changed twice in the evolution of the cetacean forelimb. First, the divergence of the early cetaceans from their even-toed relatives coincided with the reacquisition of the pentadactyl forelimb, whereas the ancestors of tetradactyl baleen whales (Mysticeti) later lost a digit again. To test whether the evolution of the cetacean forelimb is associated with positive selection or relaxation of Hoxd12 and Hoxd13, we sequenced these genes in a wide range of mammals. In Hoxd12, we found evidence of Darwinian selection associated with both episodes of cetacean forelimb reorganization. In Hoxd13, we found a novel expansion of a polyalanine tract in cetaceans compared with other mammals (17/18 residues vs. 14/15 residues, respectively), lengthening of which has previously been shown to be linked to synpolydactyly in humans and mice. Both genes also show much greater sequence variation among cetaceans than across other mammalian lineages. Our results strongly implicate 5′HoxD genes in the modulation of digit number, web forming, and the high morphological diversity of the cetacean manus.
Год издания: 2008
Авторы: Zhe Wang, Liping Yuan, Stephen J. Rossiter, Xiaoli Zuo, B. Le Rü, Hong Zhong, Na Han, Gareth Jones, Paul D. Jepson, Shuyi Zhang
Издательство: Oxford University Press
Источник: Molecular Biology and Evolution
Ключевые слова: Developmental Biology and Gene Regulation, Genetic and Clinical Aspects of Sex Determination and Chromosomal Abnormalities, Congenital heart defects research
Другие ссылки: Molecular Biology and Evolution (PDF)
Molecular Biology and Evolution (HTML)
PubMed (HTML)