title: Whole-genome sequencing reveals small genomic regions of introgression in an introduced crater lake population of threespine stickleback.
abstract: Invasive species pose a major threat to biological diversity. Although introduced populations often experience population bottlenecks, some invasive species are thought to be originated from hybridization between multiple populations or species, which can contribute to the maintenance of high genetic diversity. Recent advances in genome sequencing enable us to trace the evolutionary history of invasive species even at whole-genome level and may help to identify the history of past hybridization that may be overlooked by traditional marker-based analysis. Here, we conducted whole-genome sequencing of eight threespine stickleback (Gasterosteus aculeatus) individuals, four from a recently introduced crater lake population and four of the putative source population. We found that both populations have several small genomic regions with high genetic diversity, which resulted from introgression from a closely related species (Gasterosteus nipponicus). The sizes of the regions were too small to be detected with traditional marker-based analysis or even some reduced-representation sequencing methods. Further amplicon sequencing revealed linkage disequilibrium around an introgression site, which suggests the possibility of selective sweep at the introgression site. Thus, interspecies introgression might predate introduction and increase genetic variation in the source population. Whole-genome sequencing of even a small number of individuals can therefore provide higher resolution inference of history of introduced populations.
authors.affiliation: Division of Ecological Genetics Department of Population Genetics National Institute of Genetics Mishima Shizuoka Japan.
authors.forename: Kohta
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Evolutionary Genetics Laboratory Department of Biological Sciences Tokyo Metropolitan University Hachioji Tokyo Japan.
authors.forename: Ryutaro
authors.initials: R
authors.lastname: Miyagi
authors.affiliation: Biological Laboratory Gifu-keizai University Ogaki Gifu Japan.
authors.forename: Seiichi
authors.initials: S
authors.lastname: Mori
authors.affiliation: Evolutionary Genetics Laboratory Department of Biological Sciences Tokyo Metropolitan University Hachioji Tokyo Japan.
authors.forename: Aya
authors.initials: A
authors.lastname: Takahashi
authors.affiliation: Division of Ecology and Evolutionary Biology Graduate School of Life Sciences Tohoku University Sendai Miyagi Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Makino
authors.affiliation: Comparative Genomics Laboratory Center for Information Biology National Institute of Genetics Mishima Shizuoka Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Toyoda
authors.affiliation: Division of Ecology and Evolutionary Biology Graduate School of Life Sciences Tohoku University Sendai Miyagi Japan; Department of Genetics SOKENDAI (The Graduate University for Advanced Studies) Mishima Shizuoka Japan.
authors.forename: Asao
authors.initials: A
authors.lastname: Fujiyama
authors.affiliation: Division of Ecological Genetics Department of Population Genetics National Institute of Genetics Mishima Shizuoka Japan; Department of Genetics SOKENDAI (The Graduate University for Advanced Studies) Mishima Shizuoka Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Kitano
keywords: Biological invasion; Japan Sea stickleback; conservation genomics; exotic species; fisheries; hybridization; next‐generation sequencer; rapid evolution