title: Seascape analysis reveals regional gene flow patterns among populations of a marine planktonic diatom.
abstract: We investigated the gene flow of the common marine diatom, Skeletonema marinoi, in Scandinavian waters and tested the null hypothesis of panmixia. Sediment samples were collected from the Danish Straits, Kattegat and Skagerrak. Individual strains were established from germinated resting stages. A total of 350 individuals were genotyped by eight microsatellite markers. Conventional F-statistics showed significant differentiation between the samples. We therefore investigated whether the genetic structure could be explained using genetic models based on isolation by distance (IBD) or by oceanographic connectivity. Patterns of oceanographic circulation are seasonally dependent and therefore we estimated how well local oceanographic connectivity explains gene flow month by month. We found no significant relationship between genetic differentiation and geographical distance. Instead, the genetic structure of this dominant marine primary producer is best explained by local oceanographic connectivity promoting gene flow in a primarily south to north direction throughout the year. Oceanographic data were consistent with the significant FST values between several pairs of samples. Because even a small amount of genetic exchange prevents the accumulation of genetic differences in F-statistics, we hypothesize that local retention at each sample site, possibly as resting stages, is an important component in explaining the observed genetic structure.
authors.affiliation: Department of Biological and Environmental Sciences, University of Gothenburg, , PO Box 461, Gothenburg 405 30, Sweden, Department for Physics, Carl von Ossietzky University Oldenburg, , Carl-von-Ossietzky-Strasse 9, Oldenburg 26111, Germany, Department of Research and Development, Swedish Meteorological and Hydrological Institute, , Norrköping 601 76, Sweden, Department of Biological and Environmental Sciences, University of Gothenburg, , Tjärnö Marine Biological Laboratory, 452 96 Strömstad, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Godhe
authors.forename: Jenny
authors.initials: J
authors.lastname: Egardt
authors.forename: David
authors.initials: D
authors.lastname: Kleinhans
authors.forename: Lisa
authors.initials: L
authors.lastname: Sundqvist
authors.forename: Robinson
authors.initials: R
authors.lastname: Hordoir
authors.forename: Per R
authors.initials: PR
authors.lastname: Jonsson
mesh_terms: D017377:Diatoms / Q000235:genetics*; D051456:Gene Flow; D005838:Genotype; D018895:Microsatellite Repeats; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D058974:Phylogeography; D014872:Water Movements
keywords: Bacillariophyceae; Skeletonema marinoi; microsatellites; oceanographic connectivity