title: Anthropogenic hybridization between endangered migratory and commercially harvested stationary whitefish taxa (Coregonus spp.).
abstract: Natural hybridization plays a key role in the process of speciation. However, anthropogenic (human induced) hybridization of historically isolated taxa raises conservation issues. Due to weak barriers to gene flow and the presence of endangered taxa, the whitefish species complex is an excellent study system to investigate the consequences of hybridization in conservation. We focused on three naturally reproductively isolated whitefish taxa in Germany: the endangered, anadromous North Sea houting (NSH) and Baltic houting (BH), which were reintroduced after local extinction, and the commercially stocked European whitefish (EW). To evaluate the genetic integrity of each taxon, source and reintroduced populations of NSH and BH, and EW populations were characterized based on two mitochondrial and 17 microsatellite loci. Additionally, we investigated gill raker counts as an adaptive phenotypic trait. Even though clear genetic and phenotypic differentiation confirmed the houtings as separate evolutionarily significant units, admixture analyses revealed an extensive hybrid zone. Hybridizations were introgressive, positively correlated with genetic diversity, and were reflected in the gill raker counts. The BH distribution range showed higher heterogeneity and stronger admixture than the NSH range. Erroneous stocking with non-native genotypes best explained these patterns, which pose challenges for the conservation of the endangered NSH and BH.
authors.affiliation: Research Division Marine Ecology, Research Unit Evolutionary Ecology of Marine Fishes, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Dierking
authors.affiliation: Research Division Marine Ecology, Research Unit Evolutionary Ecology of Marine Fishes, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany ; Department of Evolutionary Ecology, Max Planck Institute for Evolutionary Biology Plön, Germany.
authors.forename: Luke
authors.initials: L
authors.lastname: Phelps
authors.affiliation: Department of Arctic and Marine Biology, Faculty of Biosciences Fisheries and Economics, University of Tromsø Tromsø, Norway.
authors.forename: Kim
authors.initials: K
authors.lastname: Præbel
authors.affiliation: Research Division Marine Ecology, Research Unit Evolutionary Ecology of Marine Fishes, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany ; Faculty of Science, University of Copenhagen Frederiksberg, Denmark.
authors.forename: Gesine
authors.initials: G
authors.lastname: Ramm
authors.affiliation: Research Division Marine Ecology, Research Unit Evolutionary Ecology of Marine Fishes, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany.
authors.forename: Enno
authors.initials: E
authors.lastname: Prigge
authors.affiliation: General Ecology & Limnology, Ecological Research Station Grietherbusch, Zoological Institute of the University of Cologne Cologne, Germany.
authors.forename: Jost
authors.initials: J
authors.lastname: Borcherding
authors.affiliation: Landesamt für Landwirtschaft, Umwelt und ländliche Räume (LLUR) Flintbek, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Brunke
authors.affiliation: Research Division Marine Ecology, Research Unit Evolutionary Ecology of Marine Fishes, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany.
authors.forename: Christophe
authors.initials: C
authors.lastname: Eizaguirre
keywords: admixture; anadromous fish; conservation; evolutionarily significant unit; gill raker; introgression; stocking