title: Genetic signatures of natural selection in a model invasive ascidian.
abstract: Invasive species represent promising models to study species' responses to rapidly changing environments. Although local adaptation frequently occurs during contemporary range expansion, the associated genetic signatures at both population and genomic levels remain largely unknown. Here, we use genome-wide gene-associated microsatellites to investigate genetic signatures of natural selection in a model invasive ascidian, Ciona robusta. Population genetic analyses of 150 individuals sampled in Korea, New Zealand, South Africa and Spain showed significant genetic differentiation among populations. Based on outlier tests, we found high incidence of signatures of directional selection at 19 loci. Hitchhiking mapping analyses identified 12 directional selective sweep regions, and all selective sweep windows on chromosomes were narrow (~8.9 kb). Further analyses indentified 132 candidate genes under selection. When we compared our genetic data and six crucial environmental variables, 16 putatively selected loci showed significant correlation with these environmental variables. This suggests that the local environmental conditions have left significant signatures of selection at both population and genomic levels. Finally, we identified "plastic" genomic regions and genes that are promising regions to investigate evolutionary responses to rapid environmental change in C. robusta.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China.|University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China.|University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China.
authors.forename: Yiyong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Marine Biodiversity Assessment and Management Team, National Marine Biodiversity Institute of Korea, 101-75 Jangsan-ro, Janghang-eup, Seocheon-gun Chungcheongnam-do 33662, Korea.
authors.forename: Changho
authors.initials: C
authors.lastname: Yi
authors.affiliation: Science Unit, Lingnan University, 8 Castle Peak Road, Tuen Mun, New Territories, Hong Kong, China.
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Fong
authors.affiliation: School of Biological Sciences, College of Natural Sciences, Seoul National University, Seoul 08826, Korea.
authors.forename: Won
authors.initials: W
authors.lastname: Kim
authors.affiliation: Ocean and Earth Science, National Oceanography Centre, University of Southampton, European Way, Southampton SO14 3ZH, United Kingdom.|Department of Zoology, University of Johannesburg, Auckland Park, 2006, Johannesburg, South Africa.
authors.forename: Marc
authors.initials: M
authors.lastname: Rius
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Haidian District, Beijing 100085, China.|University of Chinese Academy of Sciences, 19A Yuquan Road, Shijingshan District, Beijing 100049, China.
authors.forename: Aibin
authors.initials: A
authors.lastname: Zhan
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D019143:Evolution, Molecular; D014644:Genetic Variation; D005828:Genetics, Population; D058865:Introduced Species; D018895:Microsatellite Repeats; D009520:New Zealand; D056910:Republic of Korea; D012641:Selection, Genetic; D013019:South Africa; D013030:Spain; D014561:Urochordata / Q000235:genetics*