日前，最新一期PNAS杂志刊登的一项研究"Genetic adaptation to captivity can occur in a single generation"说，人工养殖可能减少孵化场的鱼在野生环境中繁殖的能力。
对硬头鳟这种美国濒危物种法案规定的受威胁物种的保护计划的一部分涉及了向野生鱼群补充孵化场繁殖的幼鱼。然而人工养殖出生的鱼常常无法适应野生环境。Mark R. Christie及其同事进行了一项对俄勒冈州的Hood河的硬头鳟的多代世系分析，从而探索养殖的鱼重新引入野外出现的适应度下降。
这组作者报告说，人工养殖的第一代鱼的繁殖成功几乎是在同样条件下产卵的野生鱼的两倍，这提示对人工养殖的遗传适应而非人工养殖的环境效应很可能是孵化场的鱼的繁殖适应度下降的原因。此外，捕获到的繁殖成功度高的鱼产生的后代在野外的表现不佳，这提示与圈养状态下成功有关联的性状可能对野外的繁殖不利。这组作者说，发现作为这种适应的基础的遗传性状可能有助于科研人员修改鱼类养殖项目和物种保护策略。（生物谷Bioon.com）
doi:10.1073/pnas.1111073109
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Genetic adaptation to captivity can occur in a single generation
Mark R. Christiea,1, Melanie L. Marinea, Rod A. Frenchb, andMichael S. Blouina
Captive breeding programs are widely used for the conservation and restoration of threatened and endangered species. Nevertheless, captive-born individuals frequently have reduced fitness when reintroduced into the wild. The mechanism for these fitness declines has remained elusive, but hypotheses include environmental effects of captive rearing, inbreeding among close relatives, relaxed natural selection, and unintentional domestication selection (adaptation to captivity). We used a multigenerational pedigree analysis to demonstrate that domestication selection can explain the precipitous decline in fitness observed in hatchery steelhead released into the Hood River in Oregon. After returning from the ocean, wild-born and first-generation hatchery fish were used as broodstock in the hatchery, and their offspring were released into the wild as smolts. First-generation hatchery fish had nearly double the lifetime reproductive success (measured as the number of returning adult offspring) when spawned in captivity compared with wild fish spawned under identical conditions, which is a clear demonstration of adaptation to captivity. We also documented a tradeoff among the wild-born broodstock: Those with the greatest fitness in a captive environment produced offspring that performed the worst in the wild. Specifically, captive-born individuals with five (the median) or more returning siblings (i.e., offspring of successful broodstock) averaged 0.62 returning offspring in the wild, whereas captive-born individuals with less than five siblings averaged 2.05 returning offspring in the wild. These results demonstrate that a single generation in captivity can result in a substantial response to selection on traits that are beneficial in captivity but severely maladaptive in the wild. .
