Roberge Christian, Normandeau Eric, Einum Sigurd, Guderley Helga, Bernatchez Louis
Département de biologie, Université Laval, Québec, Canada G1K 7P4.
Mol Ecol. 2008 Jan;17(1):314-24. doi: 10.1111/j.1365-294X.2007.03438.x.
Large annual escapees of farmed Atlantic salmon enhance the risk of extinction of wild populations through genetic and ecological interactions. Recently, we documented evolutionary change in gene transcription between farmed and wild Atlantic salmon after only five generations of artificial selection. While differences for most quantitative traits are expected to gradually dilute through repeated backcrossing to wild populations, the genetic basis of gene transcription has been shown to be largely nonadditive and hybrid crosses may display unexpected inheritance patterns. This makes it difficult to predict to what extent interbreeding between farmed and wild individuals will change the genetic makeup of wild salmon populations. Here, we compare the genome-wide gene transcription profiles of Norwegian wild salmon to that of a second generation hybrid cross [backcross: (Farmed X Wild) X Wild]. Over 6% (298, q-value < 0.01) of the detected genes exhibited highly significantly different transcription levels, and the range and average magnitude of those differences was strikingly higher than previously described between pure farmed and wild strains. Most differences appear to result from nonadditive gene interactions. These results suggest that interbreeding of fugitive farmed salmon and wild individuals could substantially modify the genetic control of gene transcription in natural populations exposed to high migration from fish farms, resulting in potentially detrimental effects on the survival of these populations. This further supports the idea that measures to considerably reduce the number of escaped farmed salmon and their reproduction in the wild are urgently needed.
养殖的大西洋鲑鱼每年大量逃逸，通过基因和生态相互作用增加了野生种群灭绝的风险。最近，我们记录了仅经过五代人工选择后养殖和野生大西洋鲑鱼之间基因转录的进化变化。虽然大多数数量性状的差异预计会通过与野生种群的反复回交而逐渐稀释，但基因转录的遗传基础已被证明在很大程度上是非加性的，杂交后代可能会表现出意想不到的遗传模式。这使得很难预测养殖个体与野生个体之间的杂交会在多大程度上改变野生鲑鱼种群的基因组成。在这里，我们将挪威野生鲑鱼的全基因组基因转录谱与第二代杂交后代【回交：（养殖×野生）×野生】的转录谱进行了比较。超过6%（298个，q值<0.01）的检测基因表现出高度显著不同的转录水平，这些差异的范围和平均幅度明显高于先前报道的纯种养殖和野生品系之间的差异。大多数差异似乎是由非加性基因相互作用导致的。这些结果表明，逃逸的养殖鲑鱼与野生个体的杂交可能会极大地改变自然种群中基因转录的遗传控制，这些自然种群面临着来自养鱼场的大量洄游鱼类，从而可能对这些种群的生存产生不利影响。这进一步支持了迫切需要采取措施大幅减少逃逸养殖鲑鱼数量及其在野外繁殖的观点。
