title: Global analysis of genes involved in freshwater adaptation in threespine sticklebacks (Gasterosteus aculeatus).
abstract: Examples of parallel evolution of phenotypic traits have been repeatedly demonstrated in threespine sticklebacks (Gasterosteus aculeatus) across their global distribution. Using these as a model, we performed a targeted genome scan--focusing on physiologically important genes potentially related to freshwater adaptation--to identify genetic signatures of parallel physiological evolution on a global scale. To this end, 50 microsatellite loci, including 26 loci within or close to (<6 kb) physiologically important genes, were screened in paired marine and freshwater populations from six locations across the Northern Hemisphere. Signatures of directional selection were detected in 24 loci, including 17 physiologically important genes, in at least one location. Although no loci showed consistent signatures of selection in all divergent population pairs, several outliers were common in multiple locations. In particular, seven physiologically important genes, as well as reference ectodysplasin gene (EDA), showed signatures of selection in three or more locations. Hence, although these results give some evidence for consistent parallel molecular evolution in response to freshwater colonization, they suggest that different evolutionary pathways may underlie physiological adaptation to freshwater habitats within the global distribution of the threespine stickleback.
authors.affiliation: Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, Helsinki, Finland. jacquelin.defaveri@helsinki.fi
authors.forename: Jacquelin
authors.initials: J
authors.lastname: DeFaveri
authors.forename: Takahito
authors.initials: T
authors.lastname: Shikano
authors.forename: Yukinori
authors.initials: Y
authors.lastname: Shimada
authors.forename: Akira
authors.initials: A
authors.lastname: Goto
authors.forename: Juha
authors.initials: J
authors.lastname: Merilä
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D017753:Ecosystem; D005060:Europe; D019143:Evolution, Molecular; D029941:Fish Proteins / Q000235:genetics; D005618:Fresh Water; D007564:Japan; D018895:Microsatellite Repeats; D009656:North America; D012641:Selection, Genetic; D023701:Smegmamorpha / Q000235:genetics* / Q000502:physiology
chemical_list: D029941:Fish Proteins