Crespel Amélie, Bernatchez Louis, Garant Dany, Audet Céline
Institut des sciences de la mer de Rimouski, Université du Québec à Rimouski, 310 Allée des Ursulines, Rimouski, QC, Canada.
Genetica. 2013 Mar;141(1-3):51-64. doi: 10.1007/s10709-013-9705-x. Epub 2013 Feb 15.
Investigating the nature of physiological traits potentially related to fitness is important towards a better understanding of how species and/or populations may respond to selective pressures imposed by contrasting environments. In northern species in particular, the ability to mobilize energy reserves to compensate for the low external energy intake during winter is crucial. However, the phenotypic and genetic bases of energy reserve accumulation and mobilization have rarely been investigated, especially pertaining to variation in strategy adopted by different populations. In the present study, we documented variation in several energy reserve variables and estimated their quantitative genetic basis to test the null hypothesis of no difference in variation at those traits among three strains of brook charr (Salvelinus fontinalis) and their reciprocal hybrids. Our results indicate that the strategy of winter energy preparation and mobilization was specific to each strain, whereby (1) domestic fish accumulated a higher amount of energy reserves before winter and kept accumulating liver glycogen during winter despite lower feeding; (2) Laval fish used liver glycogen and lipids during winter and experienced a significant decrease in condition factor; (3) Rupert fish had relatively little energy reserves accumulated at the end of fall and preferentially mobilized visceral fat during winter. Significant heritability for traits related to the accumulation and use of energy reserves was found in the domestic and Laval but not in the Rupert strain. Genetic and phenotypic correlations also varied among strains, which suggested population-specific genetic architecture underlying the expression of these traits. Hybrids showed limited evidence of non-additive effects. Overall, this study provides the first evidence of a genetically based-and likely adaptive-population-specific strategy for energy mobilization related to overwinter survival.
研究与适应性潜在相关的生理特征的本质，对于更好地理解物种和/或种群如何应对不同环境施加的选择压力至关重要。特别是在北方物种中，调动能量储备以补偿冬季外部能量摄入不足的能力至关重要。然而，能量储备积累和调动的表型和遗传基础很少被研究，尤其是关于不同种群所采用策略的差异。在本研究中，我们记录了几种能量储备变量的变化，并估计了它们的数量遗传基础，以检验三种溪红点鲑（Salvelinus fontinalis）品系及其正反交杂种在这些性状上的变异无差异的零假设。我们的结果表明，冬季能量准备和调动的策略因每个品系而异，即：（1）养殖鱼在冬季前积累了更多的能量储备，并且在冬季尽管摄食减少但仍持续积累肝糖原；（2）拉瓦尔品系的鱼在冬季利用肝糖原和脂质，且体况因子显著下降；（3）鲁珀特品系的鱼在秋季末积累的能量储备相对较少，并且在冬季优先调动内脏脂肪。在养殖品系和拉瓦尔品系中发现了与能量储备积累和利用相关性状的显著遗传力，但在鲁珀特品系中未发现。遗传和表型相关性在不同品系之间也有所不同，这表明这些性状表达背后存在种群特异性的遗传结构。杂种显示出有限的非加性效应证据。总体而言，本研究首次提供了与越冬生存相关的基于遗传且可能具有适应性的种群特异性能量调动策略的证据。
