title: Population differentiation of zander (Sander lucioperca) across native and newly colonized ranges suggests increasing admixture in the course of an invasion.
abstract: In addition to ecological factors, evolutionary processes can determine the invasion success of a species. In particular, genetic admixture has the potential to induce rapid evolutionary change, which can result from natural or human-assisted secondary contact between differentiated populations. We studied the recent range expansion of zander in Germany focusing on the interplay between invasion and genetic admixture. Historically, the rivers Elbe and Danube harboured the most north-western source populations from which a north-westward range expansion occurred. This was initiated by introducing zander outside its native range into rivers and lakes, and was fostered by migration through artificial canals and stocking from various sources. We analysed zander populations of the native and invaded ranges using nuclear and mitochondrial genetic markers. Three genetic lineages were identified, which were traced to ancestral ranges. Increased genetic diversity and admixture in the invaded region highlighted asymmetric gene flow towards this area. We suppose that the adaptive potential of the invading populations was promoted by genetic admixture, whereas competitive exclusion in the native areas provided a buffer against introgression by novel genotypes. These explanations would be in line with evidence that hybridization can drive evolutionary change under conditions when new niches can be exploited.
authors.affiliation: Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries Berlin, Germany.
authors.forename: Erik
authors.initials: E
authors.lastname: Eschbach
authors.affiliation: Max Planck Institute for Evolutionary Biology Plön, Germany.
authors.forename: Arne W
authors.initials: AW
authors.lastname: Nolte
authors.affiliation: Department of Ecophysiology and Aquaculture, Leibniz-Institute of Freshwater Ecology and Inland Fisheries Berlin, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Kohlmann
authors.affiliation: Department of Ecophysiology and Aquaculture, Leibniz-Institute of Freshwater Ecology and Inland Fisheries Berlin, Germany.
authors.forename: Petra
authors.initials: P
authors.lastname: Kersten
authors.affiliation: Department of Aquatic Ecology, Faculty of Biology, University of Duisburg-Essen Essen, Germany.
authors.forename: Jochem
authors.initials: J
authors.lastname: Kail
authors.affiliation: Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries Berlin, Germany ; Chair of Integrative Fisheries Management, Faculty of Agriculture and Horticulture, Humboldt-Universität zu Berlin Berlin, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Arlinghaus
keywords: competitive exclusion; gene flow; hybridization; local adaptation; pike-perch; secondary contact