Abstract Artificial selection can be advantageous for breeding fish that are better adapted to temperature changes induced by climate change. Selecting fish with better growth performance and survival under long term thermal stress would require an understanding of the level of additive genetic variation for these traits. Moreover, disentangling the genetic co-variation between growth- and robustness-related traits is key to understand potential antagonisms between selection for an increased performance and survivability. Thus, this study aimed at: i) assessing levels of genetic variation for growth and survival under chronic heat stress, and ii) evaluating the genetic relationship between these two traits and a broad range of growth- and robustness-related traits to identify potential trade-offs in rainbow trout. Phenotypic and pedigree records (n = 65,298 animals) from a rainbow trout breeding population were used. Growth and survival under chronic thermal stress were defined as the final body weight (FWHT) and days to death (TSR), after the experimental chronic exposure to high temperature (between 18 and 22 °C). Other growth-related traits analyzed here were: body weight at smolt stage (SW), harvest weight (HW), weight at processing plant (WPP), fillet weight (FW), weight of the eviscerated fish (GUW) and body weight at low temperature (FWLT). Robustness-related traits evaluated here were: resistance against Piscirickettsia salmonis (PSR) and Flavobacterium psychrophilum (FPR), and susceptibility to Caligus rogercresseyi (CS). The heritabilites estimated were: FWHT = 0.41 ± 0.14; TSR = 0.13 ± 0.05; SW = 0.54 ± 0.01; HW = 0.63 ± 0.01; WPP = 0.19 ± 0.02; FW = 0.03 ± 0.03; GUW = 0.18 ± 0.02; FWLT = 0.59 ± 0.17; FPR = 0.35 ± 0.05; PSR = 0.30 ± 0.05; and CS 0.08 ± 0.02. In general, strong compensations were identified between the robustness- and growth- related traits with genetic correlations that ranged from −0.28 to −0.98, except for resistance to F. psychrophilum and growth-related traits, which showed correlation values from 0.28 to 0.46. Genetic improvement for growth and survival under chronic upper thermal exposure is feasible. Compensations between growth- and robustness- related traits have to be accounted for when simultaneously including performance and disease resistance traits in the breeding objective.

中文翻译：

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虹鳟鱼在慢性热应激下的生长和存活遗传学以及与生长和健壮性相关性状的权衡

摘要 人工选择有利于培育更适应气候变化引起的温度变化的鱼类。选择在长期热应激下具有更好生长性能和存活率的鱼需要了解这些性状的附加遗传变异水平。此外，解开生长相关性状和健壮性相关性状之间的遗传共变是理解选择之间潜在对抗以提高性能和生存能力的关键。因此，本研究旨在：i) 评估在慢性热应激下生长和存活的遗传变异水平，以及 ii) 评估这两个性状和广泛的生长和健壮性相关性状之间的遗传关系，以确定潜在的贸易- 虹鳟鱼。使用了虹鳟鱼繁殖种群的表型和谱系记录（n = 65,298 只动物）。慢性热应激下的生长和存活定义为实验性慢性暴露于高温（18 至 22 °C）后的最终体重 (FWHT) 和死亡天数 (TSR)。此处分析的其他生长相关性状包括：幼鱼体重 (SW)、收获体重 (HW)、加工厂体重 (WPP)、鱼片重量 (FW)、去内脏鱼的重量 (GUW) 和低温 (FWLT)。此处评估的健壮性相关性状是：对鲑鱼 (PSR) 和嗜冷黄杆菌 (FPR) 的抗性，以及对 Caligus rogercresseyi (CS) 的易感性。估计的遗传力为：FWHT = 0.41 ± 0.14；TSR = 0.13 ± 0.05；SW = 0.54±0.01；硬件=0.63±0.01；WPP = 0.19 ± 0.02；FW = 0.03 ± 0.03；GUW = 0.18 ± 0.02；FWLT = 0.59 ± 0.17；FPR = 0.35 ± 0.05；PSR = 0.30 ± 0.05；和 CS 0.08 ± 0.02。一般而言，在健壮性和生长相关性状之间确定了强补偿，遗传相关性范围为 -0.28 至 -0.98，但对嗜冷嗜热菌的抗性和生长相关性状的相关性值为 0.28 至 0.46。在慢性高温暴露下对生长和存活的遗传改良是可行的。当在育种目标中同时包括性能和抗病性状时，必须考虑生长和健壮性相关性状之间的补偿。在健壮性和生长相关性状之间确定了强补偿，遗传相关性范围为 -0.28 至 -0.98，但对嗜冷嗜热菌的抗性和生长相关性状的相关性值为 0.28 至 0.46。在慢性高温暴露下对生长和存活的遗传改良是可行的。当在育种目标中同时包括性能和抗病性状时，必须考虑生长和健壮性相关性状之间的补偿。在健壮性和生长相关性状之间确定了强补偿，遗传相关性范围为 -0.28 至 -0.98，除了对嗜冷嗜热菌的抗性和生长相关性状，相关性值为 0.28 至 0.46。在慢性高温暴露下对生长和存活的遗传改良是可行的。当在育种目标中同时包括性能和抗病性状时，必须考虑生长和健壮性相关性状之间的补偿。