Data from: Introgression of domesticated alleles into a wild trout genotype and the impact on seasonal survival in natural lakes

We tested the fitness consequences of introgression of fast-growing domesticated fish into a wild population. Fry from wild and domesticated rainbow trout (Oncorhynchus mykiss) crosses, F1 hybrids, and first- and second-generation backcrosses were released into two natural lakes. Parentage analysis using microsatellite loci facilitated the identification of survivors so fitness was estimated in nature from the first-feeding stage. Results indicated that under certain conditions domesticated fish survived at least as well as wild fish within the same environment. Relative growth and survival of the crosses, however, was highly dependent on environment. During the first summer, fastest-growing crosses had the highest survival, but this trend was reversed after one winter and another summer. Although the F1 hybrids showed evidence of outbreeding depression due to disruption of local adaptation, there was little evidence of outbreeding depression in the backcrosses, and the second-generation backcrosses exhibited a wild-type phenotype. This information is relevant for assessing the multigenerational risk of escaped or released domesticated fish should they successfully interbreed with wild populations and provides information on how to minimize detrimental impacts of a conservation breeding and/or management program. These data also further understanding of the selection pressures in nature that maintain submaximal rates of growth.

本研究探究了快速生长的养殖鱼类渐渗（introgression）进入野生种群后对适合度的影响。将野生与养殖虹鳟（Oncorhynchus mykiss）的杂交后代、F1杂种（F1 hybrid）以及一代回交（backcross）和二代回交个体的鱼苗放归至两个天然湖泊中。通过基于微卫星位点（microsatellite loci）的亲权分析（parentage analysis），可精准识别存活个体，从而能够从首次摄食阶段起估算其在自然环境中的适合度。
研究结果表明，在特定条件下，养殖鱼类在相同生境中的存活率至少与野生鱼类相当。不过，各类杂交组合的相对生长速率与存活率高度依赖于环境条件。在首个夏季，生长最快的杂交组存活率最高，但经过一个冬季与第二个夏季后，这一趋势发生逆转。尽管F1杂种因本地适应遭到破坏而表现出远交衰退（outbreeding depression）迹象，但回交个体几乎未出现远交衰退现象，且二代回交个体呈现出野生型表型（wild-type phenotype）。
本研究结果可为评估逃逸或放归的养殖鱼类若与野生种群成功杂交所带来的多代风险提供参考，同时也能为如何降低保育繁育及/或管理计划的不利影响提供依据。此外，本数据集还增进了学界对自然界中维持亚最大生长速率的选择压力的认知。