Salmonids are some of the most widely studied species of fish worldwide. They span freshwater rivers and lakes to fjords and oceans; they include short- and long-distance anadromous migrants, as well as partially migratory and non-migratory populations; and exhibit both semelparous and iteroparous reproduction. Salmonid life-history strategies represent some of the most diverse on the planet. For this reason, salmonids provide an especially interesting model to study the drivers of these different life-history pathways. Over the past few decades, numerous studies and reviews have been published, although most have focused on ultimate considerations where expected reproductive success of different developmental or life-history strategies are compared. Those that considered proximate causes generally focused on genetics or the environment, with less consideration of physiology. Our objective was therefore to review the existing literature on the role of physiology as a proximate driver for life-history strategies in salmonids. This link is necessary to explore since physiology is at the core of biological processes influencing energy acquisition and allocation. Energy acquisition and allocation processes, in turn, can affect life histories. We find that life-history strategies are driven by a range of physiological processes, ranging from metabolism and nutritional status to endocrinology. Our review revealed that the role of these physiological processes can vary across species and individuals depending on the life-history decision(s) to be made. In addition, while findings sometimes vary by species, results appear to be consistent in species with similar life cycles. We conclude that despite much work having been conducted on the topic, the study of physiology and its role in determining life-history strategies in salmonids remains somewhat unexplored, particularly for char and trout (excluding brown trout) species. Understanding these mechanistic links is necessary if we are to understand adequately how changing environments will impact salmonid populations.

中文翻译：

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鲑鱼的生活史策略：生理学的作用及其后果

鲑鱼是世界范围内研究最广泛的鱼类之一。它们跨越淡水河流和湖泊到峡湾和海洋；他们包括短途和长途溯河移民，以及部分迁徙和非迁徙人口；并表现出半生和单生的繁殖。鲑鱼生活史策略代表了地球上最多样化的一些策略。出于这个原因，鲑鱼提供了一个特别有趣的模型来研究这些不同生活史途径的驱动因素。在过去的几十年中，已经发表了许多研究和评论，尽管大多数研究和评论都集中在最终考虑因素上，其中比较了不同发育或生活史策略的预期繁殖成功。那些考虑近因的人通常集中在遗传或环境上，较少考虑生理。因此，我们的目标是回顾现有的关于生理学作为鲑鱼生活史策略的直接驱动因素的文献。由于生理学是影响能量获取和分配的生物过程的核心，因此有必要探索这一联系。反过来，能量获取和分配过程会影响生命史。我们发现生活史策略是由一系列生理过程驱动的，从新陈代谢和营养状况到内分泌。我们的审查表明，这些生理过程的作用可能因物种和个体而异，具体取决于要做出的生活史决定。此外，虽然发现有时因物种而异，但在具有相似生命周期的物种中，结果似乎是一致的。我们得出的结论是，尽管已就该主题进行了大量工作，但生理学研究及其在确定鲑科动物生命史策略中的作用仍然有些未探索，特别是对于炭和鳟鱼（不包括褐鳟鱼）物种。如果我们要充分了解不断变化的环境将如何影响鲑鱼种群，就必须了解这些机械联系。