title: Regional environmental pressure influences population differentiation in turbot (Scophthalmus maximus).
abstract: Unravelling the factors shaping the genetic structure of mobile marine species is challenging due to the high potential for gene flow. However, genetic inference can be greatly enhanced by increasing the genomic, geographical or environmental resolution of population genetic studies. Here, we investigated the population structure of turbot (Scophthalmus maximus) by screening 17 random and gene-linked markers in 999 individuals at 290 geographical locations throughout the northeast Atlantic Ocean. A seascape genetics approach with the inclusion of high-resolution oceanographical data was used to quantify the association of genetic variation with spatial, temporal and environmental parameters. Neutral loci identified three subgroups: an Atlantic group, a Baltic Sea group and one on the Irish Shelf. The inclusion of loci putatively under selection suggested an additional break in the North Sea, subdividing southern from northern Atlantic individuals. Environmental and spatial seascape variables correlated marginally with neutral genetic variation, but explained significant proportions (respectively, 8.7% and 10.3%) of adaptive genetic variation. Environmental variables associated with outlier allele frequencies included salinity, temperature, bottom shear stress, dissolved oxygen concentration and depth of the pycnocline. Furthermore, levels of explained adaptive genetic variation differed markedly between basins (3% vs. 12% in the North and Baltic Sea, respectively). We suggest that stable environmental selection pressure contributes to relatively strong local adaptation in the Baltic Sea. Our seascape genetic approach using a large number of sampling locations and associated oceanographical data proved useful for the identification of population units as the basis of management decisions.
authors.affiliation: Institute for Agricultural and Fisheries Research (ILVO), Animal Sciences Unit - Fisheries, Ankerstraat 1, B-8400, Ostend, Belgium; Laboratory of Biodiversity and Evolutionary Genomics, University of Leuven, Charles Deberiotstraat 32, B-3000, Leuven, Belgium.
authors.forename: S G
authors.initials: SG
authors.lastname: Vandamme
authors.forename: G E
authors.initials: GE
authors.lastname: Maes
authors.forename: J A M
authors.initials: JA
authors.lastname: Raeymaekers
authors.forename: K
authors.initials: K
authors.lastname: Cottenie
authors.forename: A K
authors.initials: AK
authors.lastname: Imsland
authors.forename: B
authors.initials: B
authors.lastname: Hellemans
authors.forename: G
authors.initials: G
authors.lastname: Lacroix
authors.forename: E
authors.initials: E
authors.lastname: Mac Aoidh
authors.forename: J T
authors.initials: JT
authors.lastname: Martinsohn
authors.forename: P
authors.initials: P
authors.lastname: Martínez
authors.forename: J
authors.initials: J
authors.lastname: Robbens
authors.forename: R
authors.initials: R
authors.lastname: Vilas
authors.forename: F A M
authors.initials: FA
authors.lastname: Volckaert
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics; D000818:Animals; D001267:Atlantic Ocean; D004777:Environment; D005412:Flatfishes / Q000235:genetics*; D051456:Gene Flow; D005787:Gene Frequency; D005819:Genetic Markers; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D018895:Microsatellite Repeats; D009659:North Sea; D012641:Selection, Genetic
chemical_list: D005819:Genetic Markers
keywords: Scophthalmus maximus; adaptive genetic variation; microsatellite; oceanography; population structure; seascape genetics