Robertsen Grethe, Reid Donald, Einum Sigurd, Aronsen Tonje, Fleming Ian A, Sundt-Hansen Line E, Karlsson Sten, Kvingedal Eli, Ugedal Ola, Hindar Kjetil
Norwegian Institute for Nature Research Trondheim Norway.
School of Life Sciences, College of Medical, Veterinary and Life Sciences University of Glasgow Glasgow UK.
Ecol Evol. 2018 Dec 26;9(1):212-222. doi: 10.1002/ece3.4716. eCollection 2019 Jan.
Escaped farmed Atlantic salmon interbreed with wild Atlantic salmon, leaving offspring that often have lower success in nature than pure wild salmon. On top of this, presence of farmed salmon descendants can impair production of wild-type recruits. We hypothesize that both these effects connect with farmed salmon having acquired higher standard metabolic rates (SMR, the energetic cost of self-maintenance) during domestication. Fitness-related advantages of phenotypic traits associated with both high SMR and farmed salmon (e.g., social dominance) depend on environmental conditions, such as food availability. We hypothesize that farmed offspring have an advantage at high food availability due to, for example, dominance behavior but suffer increased risks of starvation when food is scarce because this behavior is energy-demanding. To test these hypotheses, we first compare embryo SMR of pure farmed, farmed-wild hybrids and pure wild offspring. Next, we test early-life performance (in terms of survival and growth) of hybrids relative to that of their wild half-siblings, as well as their competitive abilities, in semi-natural conditions of high and low food availability. Finally, we test how SMR affects early-life performance at high and low food availability. We find inconclusive support for the hypothesis that domestication has induced increased SMR. Further, wild and hybrid juveniles had similar survival and growth in the semi-natural streams. Yet, the presence of hybrids led to decreased survival of their wild half-siblings. Contrary to our hypothesis about context-dependency, these effects were not modified by food availability. However, wild juveniles with high SMR had decreased survival when food was scarce, but there was no such effect at high food availability. This study provides further proof that farmed salmon introgression may compromise the viability of wild salmon populations. We cannot, however, conclude that this is connected to alterations in the metabolic phenotype of farmed salmon.
逃逸的养殖大西洋鲑与野生大西洋鲑杂交，产生的后代在自然环境中的生存成功率往往低于纯种野生鲑鱼。除此之外，养殖鲑鱼后代的存在会影响野生型新个体的产生。我们推测，这两种影响都与养殖鲑鱼在驯化过程中获得了更高的标准代谢率（SMR，自我维持的能量消耗）有关。与高SMR和养殖鲑鱼相关的表型性状在适应度方面的优势（例如社会优势）取决于环境条件，如食物供应情况。我们推测，养殖后代在食物供应充足时具有优势，例如由于优势行为，但在食物稀缺时挨饿的风险会增加，因为这种行为需要消耗能量。为了验证这些假设，我们首先比较纯种养殖、养殖 - 野生杂交和纯种野生后代的胚胎SMR。接下来，我们在食物供应高低不同的半自然条件下，测试杂交后代相对于其野生半同胞的早期生活表现（以生存和生长来衡量）以及它们的竞争能力。最后，我们测试SMR如何在食物供应高低不同的情况下影响早期生活表现。我们发现对于驯化导致SMR增加这一假设的支持尚无定论。此外，野生和杂交幼鱼在半自然溪流中的生存和生长情况相似。然而，杂交后代的存在导致其野生半同胞的存活率下降。与我们关于环境依赖性的假设相反，这些影响并未因食物供应情况而改变。然而，SMR高的野生幼鱼在食物稀缺时存活率下降，但在食物供应充足时没有这种影响。这项研究进一步证明，养殖鲑鱼的基因渗入可能会损害野生鲑鱼种群的生存能力。然而，我们不能得出这与养殖鲑鱼代谢表型的改变有关的结论。
