title: Evolutionary Genetics of Hypoxia Tolerance in Cetaceans during Diving.
abstract: Hypoxia was a major challenge faced by cetaceans during the course of secondary aquatic adaptation. Although physiological traits of hypoxia tolerance in cetaceans have been well characterized, the underlying molecular mechanisms remain unknown. We investigated the sequences of 17 hypoxia-tolerance-related genes in representative cetaceans to provide a comprehensive insight into the genetic basis of hypoxia tolerance in these animals. Genes involved in carrying and transporting oxygen in the blood and muscle (hemoglobin-α and β, myoglobin), and genes involved in the regulation of vasoconstriction (endothelin-1, -2, and -3; endothelin receptor type A and B; adrenergic receptor α-1D; and arginine vasopressin) appear to have undergone adaptive evolution, evidence for positive selection on their particular sites, and radical physiochemical property changes of selected condons. Interestingly, "long-diving" cetaceans had relatively higher ω (dN/dS) values than "short-diving" cetaceans for the hemoglobin β gene, indicating divergent selective pressure presented in cetacean lineages with different diving abilities. Additionally, parallel positive selection or amino acid changes (ADRA1D: P50A, A53G,AVPR1B: I/V270T) among animals exposed to different hypoxia habitats reflect functional convergence or similar genetic mechanisms of hypoxia tolerance. In summary, positive selection, divergent selective pressures, and parallel evolution at the molecular level provided some new insights into the genetic adaptation of hypoxia tolerance.
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
authors.forename: Ran
authors.initials: R
authors.lastname: Tian
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
authors.forename: Zhengfei
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Niu
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China.
authors.forename: Kaiya
authors.initials: K
authors.lastname: Zhou
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China xushixia78@163.com gyang@njnu.edu.cn.
authors.forename: Shixia
authors.initials: S
authors.lastname: Xu
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing, China xushixia78@163.com gyang@njnu.edu.cn.
authors.forename: Guang
authors.initials: G
authors.lastname: Yang
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000818:Animals; D001798:Blood Proteins / Q000235:genetics*; D002591:Cetacea / Q000235:genetics* / Q000502:physiology; D004242:Diving; D019143:Evolution, Molecular; D000860:Hypoxia / Q000235:genetics*; D010101:Oxygen Consumption / Q000235:genetics; D010802:Phylogeny
chemical_list: D001798:Blood Proteins
keywords: Cetacean; adaptive evolution; hypoxia tolerance; positive selection