@ARTICLE{TreeBASE2Ref23703, author = {Mariana F Nery and Jos? Ignacio Arroyo and Juan C Opazo}, title = {Increased rate of hair keratin gene loss in the cetacean lineage}, year = {2014}, keywords = {Alpha keratin, adaptation, gene family evolution, cetaceans, mammals, pseudogenes}, doi = {}, url = {http://}, pmid = {}, journal = {BMC Genomics}, volume = {}, number = {}, pages = {}, abstract = {Background: Hair represents an evolutionary innovation that appeared early on mammalian evolutionary history, and presumably contributed significantly to the rapid radiation of the group. An interesting event in hair evolution has been its secondarily loss in some mammalian groups, such as cetaceans, whose hairless phenotype appears to be an adaptive response to better meet the environmental conditions. To determine whether different repertoire of keratin genes among mammals can potentially explain the phenotypic hair features of different lineages, we characterized the type I and II clusters of alpha keratins from seven mammalian species, including the hairless dolphin species representing the order Cetacea. Results: We combined the available genomic information with phylogenetic analysis to conduct a comprehensive analysis of the evolutionary patterns of keratin gene clusters. We found that both type I and II gene clusters are fairly conserved among the terrestrial mammals included in this study, with lineage specific gene duplication and gene loss. Nevertheless, there is also evidence for striking increased rate of pseudogenization in the dolphin lineage when compared to its terrestrial relatives, especially among the hair type keratins. Conclusions: Here we present a comprehensive characterization of alpha-keratin genes among mammals and elucidate the mechanisms involved in the evolution of this gene family. We identified lineage-specific gene duplications and gene loss among the Laurasiatherian and Euarchontoglires species included in the study. Interestingly, the dolphin presents an increased loss of hair-type keratin genes when compared to other terrestrial mammals. As suggested by the ?less-is-more? hypothesis, we do not rule out the possibility that the gene loss of hair type keratin genes in this species might be associated to the hairless phenotype and could have been adaptive in response to new selective pressures imposed by the colonization of a new habitat. Our study provides support for the idea that pseudogenes are not simply ?genomic fossils? but instead have adaptive roles during the evolutionary process. } }

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