Knowledge of the relative importance of genetic versus environmental determinants of major developmental transitions is pertinent to understanding phenotypic evolution. In salmonid fishes, a major developmental transition enables a risky seaward migration that provides access to feed resources. In Atlantic salmon, initiation of the migrant phenotype, and thus age of migrants, is presumably controlled via thresholds of a quantitative liability, approximated by body size expressed long before the migration. However, how well size approximates liability, both genetically and environmentally, remains uncertain. We studied 32 Atlantic salmon families in two temperatures and feeding regimes (fully fed, temporarily restricted) to completion of migration status at age 1 year. We detected a lower migrant probability in the cold (0.42) than the warm environment (0.76), but no effects of male maturation status or feed restriction. By contrast, body length in late summer predicted migrant probability and its control reduced migrant probability heritability by 50–70%. Furthermore, migrant probability and length showed high heritabilities and between-environment genetic correlations, and were phenotypically highly correlated with stronger genetic than environmental contributions. Altogether, quantitative estimates for the genetic and environmental effects predicting the migrant phenotype indicate, for a given temperature, a larger importance of genetic than environmental size effects.

中文翻译：

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遗传生长潜力，而不是表型大小，预测大西洋鲑鱼的迁移表型

了解主要发育转变的遗传与环境决定因素的相对重要性与理解表型进化有关。在鲑鱼中，一次重大的发育转变使危险的向海迁移成为可能，从而提供获取饲料资源的途径。在大西洋鲑鱼中，迁移表型的开始，以及迁移的年龄，大概是通过定量责任的阈值控制的，通过在迁移之前很久表达的体型来近似。然而，在遗传和环境方面，大小与责任的接近程度仍然不确定。我们研究了 32 个大西洋鲑鱼家族在两种温度和喂养方式（完全喂养，暂时限制）到 1 岁时完成迁移状态。我们在寒冷中检测到较低的迁徙概率 (0. 42) 比温暖的环境 (0.76)，但没有雄性成熟状态或饲料限制的影响。相比之下，夏末的体长预测了迁徙概率，其控制使迁徙概率的遗传力降低了 50-70%。此外，迁徙概率和长度显示出高遗传性和环境间遗传相关性，并且在表型上与更强的遗传而非环境贡献高度相关。总之，对预测迁徙表型的遗传和环境影响的定量估计表明，对于给定的温度，遗传比环境大小影响更重要。夏末体长预测迁徙概率，其控制使迁徙概率遗传率降低 50-70%。此外，迁徙概率和长度显示出高遗传性和环境间遗传相关性，并且在表型上与更强的遗传而非环境贡献高度相关。总之，对预测迁徙表型的遗传和环境影响的定量估计表明，对于给定的温度，遗传比环境大小影响更重要。夏末体长预测迁徙概率，其控制使迁徙概率遗传率降低 50-70%。此外，迁徙概率和长度显示出高遗传性和环境间遗传相关性，并且在表型上与更强的遗传而非环境贡献高度相关。总之，对预测迁徙表型的遗传和环境影响的定量估计表明，对于给定的温度，遗传比环境大小影响更重要。