Genetics of Microenvironmental Sensitivity of Body Weight in Rainbow Trout (Oncorhynchus mykiss) Selected for Improved Growth
Genetics of Microenvironmental Sensitivity of Body Weight in Rainbow Trout (Oncorhynchus mykiss) Selected for Improved Growth
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DOI：
10.1371/journal.pone.0038766
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发表时间：
2012-06-11
期刊：
影响因子：
3.7
通讯作者：
Jarvisalo, Otso
中科院分区：
文献类型：
--
作者：
Janhunen, Matti;Kause, Antti;Jarvisalo, Otso
基因型的微环境敏感性是指对非特异性环境因素的缓冲能力，它可以通过基因型后代在（宏观）环境中表达的性状的残留变异量来量化。由于行为、生长和生活史特征的高度多态性，养殖和野生鲑科鱼类都极易受到微环境变化的影响，但这种特征的遗传基础仍然未知。我们估计的遗传（协）方差的体重和其残留的变化，在2岁的虹鳟鱼（虹鳟鱼mykiss）使用多代数据的45,900人从芬兰国家育种计划。我们还测试了微环境敏感性是否已经改变，作为一个相关的遗传反应时，生长的遗传改良已超过五代。动物模型分析显示，存在遗传异质性的体重及其残差变异。残差变异的遗传力（0.02）显著低于体重的遗传力（0.35）。然而，体重（14%）和其残差变异（37%）的遗传变异系数是显着的，这表明在这两个性状的选择反应的巨大潜力。体重与其残差之间存在显著的负遗传相关（-0.16），即快速生长的基因型对微环境中的扰动也更耐受。遗传趋势表明，鱼的生长成功地增加了选择性育种（平均每代6%），而在同一时期的剩余变异没有发生遗传变化。结果表明，体重的遗传改良不会导致微环境敏感性的伴随增加。然而，对于商业化生产，如果将这两个标准都包括在选择指数中，则可能有很大的潜力同时改善增重并增加其均匀性。
Microenvironmental sensitivity of a genotype refers to the ability to buffer against non-specific environmental factors, and it can be quantified by the amount of residual variation in a trait expressed by the genotype's offspring within a (macro) environment. Due to the high degree of polymorphism in behavioral, growth and life-history traits, both farmed and wild salmonids are highly susceptible to microenvironmental variation, yet the heritable basis of this characteristic remains unknown. We estimated the genetic (co)variance of body weight and its residual variation in 2-year-old rainbow trout (Oncorhynchus mykiss) using a multigenerational data of 45,900 individuals from the Finnish national breeding programme. We also tested whether or not microenvironmental sensitivity has been changed as a correlated genetic response when genetic improvement for growth has been practiced over five generations. The animal model analysis revealed the presence of genetic heterogeneity both in body weight and its residual variation. Heritability of residual variation was remarkably lower (0.02) than that for body weight (0.35). However, genetic coefficient of variation was notable in both body weight (14%) and its residual variation (37%), suggesting a substantial potential for selection responses in both traits. Furthermore, a significant negative genetic correlation (-0.16) was found between body weight and its residual variation, i.e., rapidly growing genotypes are also more tolerant to perturbations in microenvironment. The genetic trends showed that fish growth was successfully increased by selective breeding (an average of 6% per generation), whereas no genetic change occurred in residual variation during the same period. The results imply that genetic improvement for body weight does not cause a concomitant increase in microenvironmental sensitivity. For commercial production, however, there may be high potential to simultaneously improve weight gain and increase its uniformity if both criteria are included in a selection index.