Strait Jeffrey T, Eby Lisa A, Kovach Ryan P, Muhlfeld Clint C, Boyer Matthew C, Amish Stephen J, Smith Seth, Lowe Winsor H, Luikart Gordon
Wildlife Biology Program, W.A. Franke College of Forestry and Conservation University of Montana Missoula MT USA.
Flathead Lake Biological Station, Fish and Wildlife Genomics Group Division of Biological Sciences University of Montana Polson MT USA.
Evol Appl. 2020 Dec 18;14(3):821-833. doi: 10.1111/eva.13163. eCollection 2021 Mar.
Human-mediated hybridization threatens many native species, but the effects of introgressive hybridization on life-history expression are rarely quantified, especially in vertebrates. We quantified the effects of non-native rainbow trout admixture on important life-history traits including growth and partial migration behavior in three populations of westslope cutthroat trout over five years. Rainbow trout admixture was associated with increased summer growth rates in all populations and decreased spring growth rates in two populations with cooler spring temperatures. These results indicate that non-native admixture may increase growth under warmer conditions, but cutthroat trout have higher growth rates during cooler periods. Non-native admixture consistently increased expression of migratory behavior, suggesting that there is a genomic basis for life-history differences between these species. Our results show that effects of interspecific hybridization on fitness traits can be the product of genotype-by-environment interactions even when there are minor differences in environmental optima between hybridizing species. These results also indicate that while environmentally mediated traits like growth may play a role in population-level consequences of admixture, strong genetic influences on migratory life-history differences between these species likely explains the continued spread of non-native hybridization at the landscape-level, despite selection against hybrids at the population-level.
人类介导的杂交对许多本地物种构成威胁，但渐渗杂交对生活史表达的影响很少被量化，尤其是在脊椎动物中。我们在五年时间里，对三个西部斜坡割喉鳟种群中，非本地虹鳟鱼混合基因对包括生长和部分洄游行为在内的重要生活史特征的影响进行了量化。虹鳟鱼混合基因与所有种群夏季生长率的增加以及两个春季温度较低种群春季生长率的降低有关。这些结果表明，非本地混合基因可能在温暖条件下促进生长，但割喉鳟在较凉爽时期的生长率更高。非本地混合基因持续增加了洄游行为的表达，这表明这些物种之间生活史差异存在基因组基础。我们的结果表明，即使杂交物种之间的环境最适值存在微小差异，种间杂交对适应性特征的影响也可能是基因型与环境相互作用的产物。这些结果还表明，虽然像生长这样受环境介导的特征可能在混合基因的种群水平后果中起作用，但这些物种之间洄游生活史差异受到的强大遗传影响，可能解释了非本地杂交在景观水平上的持续扩散，尽管在种群水平上存在对杂交种的选择。
