Monster Seminar JAM - Hybridization between native westslope cutthroat trout and introduced rainbow trout: Genomic extinction or adaptive evolution?
Dr. Clint Muhlfeld, Northern Rocky Mountain Science Center, USGS
Human-mediated hybridization is a leading cause of biodiversity loss worldwide. How hybridization affects ecological adaptations and what level of hybridization is permissible pose difficult conservation questions with little empirical information to guide policy and management decisions. This is particularly true for salmonids, where widespread introgression among nonnative and native taxa has often created hybrid swarms over extensive geographic areas resulting in genomic extinction. Interbreeding between westslope cutthroat trout (Oncorhynchus clarkii lewisi) with nonnative rainbow trout (O. mykiss) exemplifies the conservation challenges of interspecific hybridization. Clint will present over 10 years of research in Montana that has investigated the behavioral, ecological, and fitness consequences of hybridization and the factors influencing the spread of hybridization between native westslope cutthroat trout and introduced rainbow trout. The combined results suggest that hybrids are not only genetically different than westslope cutthroat trout but also have reduced fitness and are ecologically different, and that hybridization is likely to continue to spread if hybrid populations with high amounts of rainbow trout admixture are not reduced or eliminated. Results indicate that extant aboriginal cutthroat trout are at greater conservation risk due to hybridization than previously thought and policies that protect hybridized populations need reconsideration.
Date and Time:
April 29, 2010,
11:00 am - 12:00 pm