Environmental and genetic factors affecting physiological performance in salmonids

太平洋鲑鱼在淡水和海水之间迁徙时，必须经历一个显著的转变，以维持体内的平衡。从溪流栖息幼鱼到洄游幼鱼的转变具有一系列复杂的发育事件，这些事件为鱼类进入海水做了准备。随着春天白昼和温度的增加，荷尔蒙的变化会刺激这种生理现象。我们对成年鲑鱼洄游回淡水时发生的生理变化所知甚少。在物种之间和物种内部，维持体内盐分平衡的机制是相似的。然而，海水和淡水之间在迁移的年龄、规模和时间上有相当大的差异。这种生活史特征的可变性为鱼类开发新栖息地或对自然或人为干扰造成的环境快速变化作出反应提供了一种机制。基因在生理适应中所起的作用，使鲑鱼能够开发新的，或在受干扰的栖息地中生存，还没有得到很好的理解。拟议研究的目的是比较来自不同地理区域的鲑鱼的生理表现，并检查它们在自然适应的环境条件下的生长、发育和生存。此外，物理因素的变化将用于评估不同人群的表现。这些研究的进一步方法将是通过从不同的鲑鱼种群中创建家庭和通过修改倍性来改变基因型。研究表型表达的环境、发育和遗传基础是了解鲑鱼离子平衡控制机制的新途径。拟议的工作将深入了解基因不同的鲑鱼对环境变化的反应能力。此外，这项工作还有许多实际应用。了解遗传和环境因素之间的相互作用将有利于选择菌株，以恢复野生种群和水产养殖生产。

Pacific salmon must undergo a remarkable transformation to maintain internal equilibrium as they migrate between fresh- and seawater. The change from stream dwelling parr to migratory smolt is characterized by a complex series of developmental events that prepare fish for entry into seawater. Hormonal changes in response to springtime increases in daylight and temperature stimulate the physiological phenomenon known as smolting. We know considerably less about the physiological changes that occur in maturing adult salmon as they migrate back to freshwater. Among and within species, the mechanisms for maintaining internal salt balance are similar. There is considerable variation, however, in the age, size and timing of migration between seawater and freshwater. This variability in life history traits provides a mechanism for fish to exploit new habitats or respond to rapid changes in their environment that occur naturally or due to human disturbance. The role genetics plays in the physiological adaptations that allow salmon to exploit new, or survive in disturbed habitats, is not well understood. The objective of the proposed research is to compare physiological performance of salmon from divergent geographic regions and examine their growth, development and survival under environmental conditions to which they are naturally adapted. In addition, changes in physical factors will be used to assess performance among different populations. A further approach for these investigations will be to alter the genotype through the creation of families from different populations of salmon and by modifying ploidy. The investigation of environmental, developmental and genetic bases of phenotypic expression is a novel approach to understanding the mechanisms controlling ion balance in salmon. The proposed work will provide insight into the ability of salmonids that differ genetically to respond to changes in the environment. In addition, there are a number of practical applications to this work. Understanding the interactions between genetic and environmental factors will benefit selection of strains for re-establishment of wild runs and for aquaculture production.