Habituation and individual variation in the endocrine stress response in the Trinidadian guppy (Poecilia reticulata) (article)
Houslay, T; Earley, R; Young, A; et al.Wilson, A
Date: 16 October 2018
Article
Journal
General and Comparative Endocrinology
Publisher
Elsevier
Publisher DOI
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Abstract
The vertebrate stress response enables individuals to react to and cope with
environmental challenges. A crucial aspect of the stress response is the elevation of
circulating glucocorticoids. However, continued activation of the stress response under
repeated exposure to stressors can be damaging to fitness. Under certain ...
The vertebrate stress response enables individuals to react to and cope with
environmental challenges. A crucial aspect of the stress response is the elevation of
circulating glucocorticoids. However, continued activation of the stress response under
repeated exposure to stressors can be damaging to fitness. Under certain circumstances
it may therefore be adaptive to habituate to repeated exposures to a particular stressor
by reducing the magnitude of any associated release of glucocorticoids. Here, we
investigate whether Trinidadian guppies (Poecilia reticulata) habituate to repeated
exposure to a mild stressor, using a waterborne hormone sampling approach that has
previously been shown to elicit a stress response in small fish. We also test for
individual variation in the extent of habituation to this stressor. Concentrating on freely
circulating cortisol, we found that the first exposure to the assay induced high cortisol
release rates but that guppies tended to habituate quickly to subsequent exposures.
There were consistent differences among individuals in their average cortisol release
rate (after accounting for effects of variables such as body size) over repeated
exposures. Our analyses did not find evidence of individual differences in habituation
rate, although limitations in statistical power could account for this finding. We repeated
the analysis for free 11-ketotestosterone, which can also respond to stressors, but found
no obvious habituation pattern and no among-individual variation. We also present data
on conjugated forms of both hormones, which were repeatable but did not show the
expected time-lagged habituation effect. We discuss consistent individual differences
around the general pattern of habituation in the flexible stress response, and highlight
the potential for individual variation in habituation to facilitate selection against the
deleterious effects of chronic stress.
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