日前，最新一期PNAS雜志刊登的一項(xiàng)研究"Genetic adaptation to captivity can occur in a single generation"說(shuō),，人工養(yǎng)殖可能減少孵化場(chǎng)的魚在野生環(huán)境中繁殖的能力。
對(duì)硬頭鱒這種美國(guó)瀕危物種法案規(guī)定的受威脅物種的保護(hù)計(jì)劃的一部分涉及了向野生魚群補(bǔ)充孵化場(chǎng)繁殖的幼魚,。然而人工養(yǎng)殖出生的魚常常無(wú)法適應(yīng)野生環(huán)境。Mark R. Christie及其同事進(jìn)行了一項(xiàng)對(duì)俄勒岡州的Hood河的硬頭鱒的多代世系分析,，從而探索養(yǎng)殖的魚重新引入野外出現(xiàn)的適應(yīng)度下降,。
這組作者報(bào)告說(shuō)，人工養(yǎng)殖的第一代魚的繁殖成功幾乎是在同樣條件下產(chǎn)卵的野生魚的兩倍,，這提示對(duì)人工養(yǎng)殖的遺傳適應(yīng)而非人工養(yǎng)殖的環(huán)境效應(yīng)很可能是孵化場(chǎng)的魚的繁殖適應(yīng)度下降的原因,。此外，捕獲到的繁殖成功度高的魚產(chǎn)生的后代在野外的表現(xiàn)不佳,，這提示與圈養(yǎng)狀態(tài)下成功有關(guān)聯(lián)的性狀可能對(duì)野外的繁殖不利,。這組作者說(shuō),，發(fā)現(xiàn)作為這種適應(yīng)的基礎(chǔ)的遺傳性狀可能有助于科研人員修改魚類養(yǎng)殖項(xiàng)目和物種保護(hù)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. .
