title: Dispersal and selection mediate hybridization between a native and invasive species.
abstract: Hybridization between native and non-native species has serious biological consequences, but our understanding of how dispersal and selection interact to influence invasive hybridization is limited. Here, we document the spread of genetic introgression between a native (Oncorhynchus clarkii) and invasive (Oncorhynchus mykiss) trout, and identify the mechanisms influencing genetic admixture. In two populations inhabiting contrasting environments, non-native admixture increased rapidly from 1984 to 2007 and was driven by surprisingly consistent processes. Individual admixture was related to two phenotypic traits associated with fitness: size at spawning and age of juvenile emigration. Fish with higher non-native admixture were larger and tended to emigrate at a younger age--relationships that are expected to confer fitness advantages to hybrid individuals. However, strong selection against non-native admixture was evident across streams and cohorts (mean selection coefficient against genotypes with non-native alleles (s) = 0.60; s.e. = 0.10). Nevertheless, hybridization was promoted in both streams by the continuous immigration of individuals with high levels of non-native admixture from other hybrid source populations. Thus, antagonistic relationships between dispersal and selection are mediating invasive hybridization between these fish, emphasizing that data on dispersal and natural selection are needed to fully understand the dynamics of introgression between native and non-native species.
authors.affiliation: US Geological Survey, Northern Rocky Mountain Science Center, Glacier National Park, West Glacier, MT 59936, USA Flathead Lake Biological Station, Fish and Wildlife Genomics Group, Division of Biological Sciences, University of Montana, Polson, MT 59860, USA rkovach@usgs.gov.
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Kovach
authors.affiliation: US Geological Survey, Northern Rocky Mountain Science Center, Glacier National Park, West Glacier, MT 59936, USA.
authors.forename: Clint C
authors.initials: CC
authors.lastname: Muhlfeld
authors.affiliation: Montana Fish Wildlife and Parks, Kalispell, MT 59901, USA.
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Boyer
authors.affiliation: Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA.
authors.forename: Winsor H
authors.initials: WH
authors.lastname: Lowe
authors.affiliation: Fish and Wildlife Genomics Group, Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA.
authors.forename: Fred W
authors.initials: FW
authors.lastname: Allendorf
authors.affiliation: Flathead Lake Biological Station, Fish and Wildlife Genomics Group, Division of Biological Sciences, University of Montana, Polson, MT 59860, USA.
authors.forename: Gordon
authors.initials: G
authors.lastname: Luikart
mesh_terms: D063147:Animal Distribution; D000818:Animals; D004272:DNA, Mitochondrial / Q000235:genetics; D005838:Genotype; D006824:Hybridization, Genetic; D058865:Introduced Species; D017683:Oncorhynchus; D012641:Selection, Genetic
chemical_list: D004272:DNA, Mitochondrial
keywords: dispersal; fitness; hybridization; introgression; invasive species; selection