Bailey Michael M, Lachapelle Kevin A, Kinnison Michael T
School of Biology and Ecology, University of Maine Orono, ME, USA.
Evol Appl. 2010 Jul;3(4):340-51. doi: 10.1111/j.1752-4571.2009.00115.x. Epub 2010 Jan 27.
Captive rearing often alters the phenotypes of organisms that are destined for release into the wild. Natural selection on these unnatural phenotypes could have important consequences for the utility of captive rearing as a restoration approach. We show that normal hatchery practices significantly advance the development of endangered Atlantic salmon (Salmo salar) fry by 30+ days. As a result, hatchery fry might be expected to face strong natural selection resulting from their developmental asynchrony. We investigated patterns of ontogenetic selection acting on hatchery produced salmon fry by experimentally manipulating fry development stage at stocking. Contrary to simple predictions, we found evidence for strong stabilizing selection on the ontogeny of unfed hatchery fry, with weaker evidence for positive directional selection on the ontogeny of fed fry. These selection patterns suggest a seasonally independent tradeoff between abiotic or biotic selection favoring advanced development and physiological selection linked to risk of starvation in unfed fry. We show, through a heuristic exercise, how such selection on ontogeny may exacerbate problems in restoration efforts by impairing fry productivity and reducing effective population sizes by 13-81%.
圈养繁殖常常会改变那些注定要放归野外的生物的表型。对这些非自然表型进行自然选择可能会对圈养繁殖作为一种恢复手段的效用产生重要影响。我们发现，正常的孵化场养殖方式会使濒危的大西洋鲑（Salmo salar）鱼苗的发育显著提前30多天。因此，预计孵化场鱼苗可能会因其发育不同步而面临强烈的自然选择。我们通过在放养鱼苗时实验性地操纵鱼苗发育阶段，研究了作用于孵化场生产的鲑鱼苗的个体发育选择模式。与简单预测相反，我们发现有证据表明对未喂食的孵化场鱼苗的个体发育存在强烈的稳定选择，而对喂食鱼苗的个体发育存在正向定向选择的证据较弱。这些选择模式表明，在有利于提前发育的非生物或生物选择与未喂食鱼苗中与饥饿风险相关的生理选择之间存在季节性无关的权衡。我们通过一项启发式分析表明，这种对个体发育的选择可能会通过损害鱼苗生产力并使有效种群规模减少13 - 81%，从而加剧恢复工作中的问题。
