Evolution of the hormonal control of animal performance: insights from the seaward migration of salmon

Integrative and Comparative Biology



The endocrine system is the key mediator of environmental and developmental (internal) information, and is likely to be involved in altering the performance of animals when selection has favored phenotypic plasticity. The endocrine control of performance should be especially pronounced in animals that undergo a developmental shift in niche, such as occurs in migratory species. By way of example, I review the developmental and environmental control of the preparatory changes for seawater entry of juvenile salmon (known as smolting) and its hormonal regulation. There is a size threshold for smolt development in juvenile Atlantic salmon that results in greater sensitivity of the growth hormone and cortisol axes to changes in daylength. These hormones, in turn, have broad effects on survival, ion homeostasis, growth and swimming performance during entry into seawater. Migratory niche shifts and metamorphic events are extreme examples of the role of hormones in animal performance and represent one end of a continuum. A framework for predicting when hormones will be involved in performance of animals is presented. Endocrine involvement in performance will be more substantial when (1) selection differentials on traits underlying performance are high and temporally discontinuous over an animal's lifetime, (2) the energetic and fitness costs of maintaining performance plasticity are less than those of constant performance, (3) cues for altering performance are reliable indicators of critical environmental conditions, require neurosensory input, and minimize effects of lag, and (4) the need for coordination of organs, tissues and cells to achieve increased performance is greater. By examining these impacts of selection, endocrinologists have an opportunity to contribute to the understanding of performance, phenotypic plasticity, and the evolution of life-history traits.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Evolution of the hormonal control of animal performance: insights from the seaward migration of salmon
Series title Integrative and Comparative Biology
DOI 10.1093/icb/icp044
Volume 49
Issue 4
Year Published 2009
Language English
Publisher Oxford University Press
Contributing office(s) Conte Anadromous Fish Research Center
Description 15 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Integrative and Comparative Biology
First page 408
Last page 422
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