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New CU- Boulder study clarifies diversity, distribution of cutthroat trout in Colorado I Uni... Page 2 of 4 Metcalf and her colleagues first collected multiple samples of tissue and bone from each of the ethanol- pickled trout specimens, obtaining fragments of DNA that were amplified and then pieced together like a high -tech jigsaw puzzle to reveal two genes of the individual specimens. The tests were conducted on two different continents under highly sterile conditions and each DNA sequencing effort was repeated several times for many specimens to ensure accuracy in the study, Metcalf said. Roughly half of the study was conducted at CU- Boulder and half at the Australian Center for Ancient DNA at the University of Adelaide, where Metcalf had worked for two years. "By conducting repeatable research at two very different, state -of -the -art laboratories, we were able to show the Bear Creek trout was the same strain as the cutthroats originally occupying the South Platte River drainage." The Bear Creek trout strain is now being propagated in the Colorado Parks and Wildlife hatchery system and at the USFWS Leadville National Fish Hatchery. In addition to identifying the Bear Creek cutthroat trout, Metcalf and her colleagues discovered a previously unknown cutthroat strain native to the San Juan Basin in southwestern Colorado that has since gone extinct. The study also confirmed that the yellowfin cutthroat, a subspecies from the Arkansas River headwaters that grew to prodigious size in Twin Lakes near Leadville, also had gone extinct. Fortunately, most fish preserved by naturalists before igoo were "fixed" in ethanol, which makes it easier for researchers to obtain reliable DNA than from fish preserved in a formaldehyde solution, a practice that later became popular. Prior to the new study -- which included DNA from specimens up to about 150 years old -- scientists working in ancient DNA labs had only performed similar research on ethanol- preserved museum vertebrate specimens less than loo years old. "One of the exciting things to come from this research project is that it opens up the potential for scientists to sequence the genes of other fish, reptiles and amphibian specimens preserved in ethanol further back in time than ever before to answer ecological questions about past diversity and distribution," said Metcalf, who conducts her research at CU's BioFrontiers Institute. Funding for the study was provided by agencies of the Greenback Cutthroat Trout Recovery Team, including the USFWS, the U.S. Forest Service, the Bureau of Land Management, the National Park Service and Trout Unlimited. "I think in many cases success depends less on the application of a new technology and more on the convergence of people with shared interest and complementary skills necessary for solving difficult problems," said Martin. "Our greenback story is really one about what can be discovered when dedicated and talented people collaborate with a shared purpose." "We've known for some time that the trout in Bear Creek were unique," said Doug Krieger, senior aquatic biologist for Colorado Parks and Wildlife and the Greenback Cutthroat Trout Recovery Team leader. "But we didn't realize they were the only surviving greenback population." The decline of native cutthroats in Colorado occurred because of a combination of pollution, overfishing and stocking of native and non- native species of trout, said Metcalf. "It's ironic that stocking nearly drove the greenback cutthroat trout to extinction, and a particularly early stocking event actually saved it from extinction," she said. Contact: Jessica Metcalf, 720- 224-5522 j essicaLmetcalf cTgmail.com Andrew Martin, 303 - 492 -2573 Andrew.M artin- 1Ccolorado.edu Jim Scott, CU- Boulder media relations, 303-492-3114 Jim. Scott Cad colo rado. edu http: / /www. colorado. edu/ news /releases/ 2012 /09/24/ new -cu- boulder - study - clarifies - diversi... 9/26/2012