title: Legacy introductions and climatic variation explain spatiotemporal patterns of invasive hybridization in a native trout.
abstract: Hybridization between invasive and native species, a significant threat to worldwide biodiversity, is predicted to increase due to climate-induced expansions of invasive species. Long-term research and monitoring are crucial for understanding the ecological and evolutionary processes that modulate the effects of invasive species. Using a large, multidecade genetics dataset (N = 582 sites, 12,878 individuals) with high-resolution climate predictions and extensive stocking records, we evaluate the spatiotemporal dynamics of hybridization between native cutthroat trout and invasive rainbow trout, the world's most widely introduced invasive fish, across the Northern Rocky Mountains of the United States. Historical effects of stocking and contemporary patterns of climatic variation were strongly related to the spread of hybridization across space and time. The probability of occurrence, extent of, and temporal changes in hybridization increased at sites in close proximity to historical stocking locations with greater rainbow trout propagule pressure, warmer water temperatures, and lower spring precipitation. Although locations with warmer water temperatures were more prone to hybridization, cold sites were not protected from invasion; 58% of hybridized sites had cold mean summer water temperatures (<11°C). Despite cessation of stocking over 40 years ago, hybridization increased over time at half (50%) of the locations with long-term data, the vast majority of which (74%) were initially nonhybridized, emphasizing the chronic, negative impacts of human-mediated hybridization. These results show that effects of climate change on biodiversity must be analyzed in the context of historical human impacts that set ecological and evolutionary trajectories.
authors.affiliation: Northern Rocky Mountain Science Center, U.S. Geological Survey, West Glacier, MT, USA.|Flathead Lake Biological Station, Division of Biological Sciences, University of Montana, Polson, MT, USA.
authors.forename: Clint C
authors.identifier: 0000-0002-4599-4059
authors.initials: CC
authors.lastname: Muhlfeld
authors.affiliation: Northern Rocky Mountain Science Center, U.S. Geological Survey, West Glacier, MT, USA.
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Kovach
authors.affiliation: Northern Rocky Mountain Science Center, U.S. Geological Survey, Bozeman, MT, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Al-Chokhachy
authors.affiliation: Flathead Lake Biological Station, Division of Biological Sciences, University of Montana, Polson, MT, USA.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Amish
authors.affiliation: Northern Rocky Mountain Science Center, U.S. Geological Survey, Bozeman, MT, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Kershner
authors.affiliation: Montana Fish, Wildlife and Parks, Missoula, MT, USA.
authors.forename: Robb F
authors.initials: RF
authors.lastname: Leary
authors.affiliation: Division of Biological Sciences, University of Montana, Missoula, MT, USA.
authors.forename: Winsor H
authors.initials: WH
authors.lastname: Lowe
authors.affiliation: Flathead Lake Biological Station, Division of Biological Sciences, University of Montana, Polson, MT, USA.
authors.forename: Gordon
authors.initials: G
authors.lastname: Luikart
authors.affiliation: Flathead Lake Biological Station, Division of Biological Sciences, University of Montana, Polson, MT, USA.
authors.forename: Phil
authors.initials: P
authors.lastname: Matson
authors.affiliation: Montana Fish, Wildlife and Parks, Missoula, MT, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Schmetterling
authors.affiliation: B.B. Shepard & Associates, Livingston, MT, USA.
authors.forename: Bradley B
authors.initials: BB
authors.lastname: Shepard
authors.affiliation: School of Fisheries and Ocean Sciences, University of Alaska, Fairbanks, AK, USA.
authors.forename: Peter A H
authors.initials: PAH
authors.lastname: Westley
authors.affiliation: Flathead Lake Biological Station, Division of Biological Sciences, University of Montana, Polson, MT, USA.
authors.forename: Diane
authors.initials: D
authors.lastname: Whited
authors.affiliation: Wildlife Biology Program, Department of Ecosystem and Conservation Sciences, College of Forestry and Conservation, University of Montana, Missoula, MT, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Whiteley
authors.affiliation: Division of Biological Sciences, University of Montana, Missoula, MT, USA.
authors.forename: Fred W
authors.initials: FW
authors.lastname: Allendorf
mesh_terms: D000818:Animals; D057231:Climate Change; D006801:Humans; D006824:Hybridization, Genetic; D058865:Introduced Species; D017686:Oncorhynchus mykiss / Q000235:genetics* / Q000502:physiology; D013696:Temperature; D014337:Trout / Q000235:genetics* / Q000502:physiology
keywords: biodiversity; climate change; cutthroat trout; hybridization; introgression; invasion; propagule pressure; translocation