A new article by researchers from the University of Montana, the U.S. Geological Survey and Montana Fish, Wildlife & Parks asserts that climate warming is increasing the hybridization of trout – interbreeding between native and non-native species – in the interior western United States.
Clint Muhlfeld, a research assistant professor in the UM Division of Biological Sciences’ Flathead Lake Biological Station and research ecologist with the USGS Northern Rocky Mountain Science Center in Glacier National Park, is the lead author of the article, titled “Invasive hybridization in a threatened species is accelerated by climate change,” which was published in the latest issue of Nature Climate Change. Co-authors are Ryan Kovach, a postdoctoral scholar at UM’s Flathead Lake Biological Station, and Leslie Jones, a UM doctoral student who works with Muhlfeld and USGS.
Specifically, rapid increases in stream temperature and decreases in spring flow over the past several decades contributed to the spread of hybridization between native westslope cutthroat trout and the introduced rainbow trout – the world’s most widely introduced invasive fish – across the Flathead River system in Montana and British Columbia, Canada.
Experts have hypothesized that climate change could decrease worldwide biodiversity through cross-breeding between invasive and native species, but this study is the first to directly and scientifically support this prediction. The study was based on 30 years of research by scientists with UM, USGS and Montana FWP.
Hybridization has contributed to the decline and extinction of many native fishes worldwide, including all subspecies of cutthroat trout in western North America, which have enormous ecological and socioeconomic value. The researchers used long-term genetic monitoring data coupled with high-resolution climate and stream temperature predictions to measure whether climate warming enhances interactions between native and non-native species through hybridization.
“Climatic changes are threatening highly prized native trout as introduced rainbow trout continue to expand their range and hybridize with native populations through climate-induced ‘windows of opportunity,’ putting many populations and species at greater risk than previously thought,” Muhlfeld said.
“The study illustrates that protecting genetic integrity and diversity of native species will be incredibly challenging when species are threatened with climate-induced invasive hybridization,” he said.
Westslope cutthroat trout and rainbow trout both spawn in the spring and can produce fertile offspring when they interbreed. Over time, a mating population of native and non-native fish will result in only hybrid individuals with substantially reduced fitness because their genomes have been altered by non-native genes that are maladapted to the local environment. Protecting and maintaining the genetic integrity of native species is important for a species’ ability to be resilient and better adapt to a rapidly changing climate.
Historical genetic samples revealed that hybridization between the two species was largely confined to one downstream Flathead River population. However, the study noted, during the past 30 years, hybridization rapidly spread upstream, irreversibly reducing the genetic integrity of native westslope cutthroat trout populations. Genetically pure populations of westslope cutthroat trout are known to occupy less than 10 percent of their historical range.
The rapid increase in hybridization was associated with climatic changes in the region. From 1978 to 2008, the rate of warming nearly tripled in the Flathead basin, resulting in earlier spring runoff, lower spring flooding and flows, and warming summer stream temperatures. Those locations with the greatest changes in stream flow and temperature experienced the greatest increases in hybridization.
Relative to cutthroat trout, rainbow trout prefer these climate-induced changes and tolerate greater environmental disturbance. These conditions likely have enhanced rainbow trout spawning and population numbers, leading to massive expansion of hybridization with westslope cutthroat trout.
“The evolutionary consequences of climate change are one of our greatest areas of uncertainty because empirical data addressing this issue are extraordinarily rare,” Kovach said. “This study is a tremendous step forward in our understanding of how climate change can influence evolutionary process and ultimately species biodiversity.”
Overall, aquatic ecosystems in western North America are predicted to experience earlier snowmelt in the spring, reduced late spring and summer flows, warmer and drier summers, and increased water temperatures – all of which indicate increased hybridization between these species.
Additional UM-affiliated authors are UM Wildlife Biology Program Director Winsor Lowe, UM Associate Professor of Conservation Ecology Gordon Luikart and Regents Professor Emeritus Fred Allendorf. Authors not affiliated with UM are Robert Al-Chokhachy with the USGS Northern Rocky Mountain Science Center, Matthew Boyer with Montana FWP in Kalispell and Robb Leary with Montana FWP in Missoula.
The study was supported by the Great Northern Landscape Conservation Cooperative, the U.S. Department of the Interior’s Northwest Climate Science Center, the National Climate Change and Wildlife Science Center, the National Science Foundation and Bonneville Power Administration.
Clint Muhlfeld, research assistant professor, UM Division of Biological Sciences, 406-600-9686, firstname.lastname@example.org .
Clint Muhlfeld | Eurek Alert!
The causes of soil consumption
14.06.2016 | Schweizerischer Nationalfonds SNF
Fishing prohibitions produce more sharks along with problems for fishing communities
09.06.2016 | Wildlife Conservation Society
Physicists in Innsbruck have realized the first quantum simulation of lattice gauge theories, building a bridge between high-energy theory and atomic physics. In the journal Nature, Rainer Blatt‘s and Peter Zoller’s research teams describe how they simulated the creation of elementary particle pairs out of the vacuum by using a quantum computer.
Elementary particles are the fundamental buildings blocks of matter, and their properties are described by the Standard Model of particle physics. The...
A year and a half on the outer wall of the International Space Station ISS in altitude of 400 kilometers is a real challenge. Whether a primordial bacterium...
Researchers at Case Western Reserve University have developed a way to swiftly and precisely control electron spins at room temperature.
A physics experiment performed at the National Institute of Standards and Technology (NIST) has enhanced scientists' understanding of how free neutrons decay...
Chemically the same, graphite and diamonds are as physically distinct as two minerals can be, one opaque and soft, the other translucent and hard. What makes...
09.06.2016 | Event News
24.05.2016 | Event News
20.05.2016 | Event News
27.06.2016 | Physics and Astronomy
27.06.2016 | Life Sciences
27.06.2016 | Awards Funding