Meeting Abstract
The stress response is an integrated set of behavioural and physiological changes that allow animals to respond to challenges in their environment. Individual variation in the dynamics of the stress response is a key aspect of an individual’s phenotype, affecting its interaction with the environment. Experience of stressors during ontogeny is known to influence adult stress responses, which are physiologically mediated in part by the glucocorticoid hormone, cortisol. While there are examples of single stressors early in life affecting adult phenotypes, much less well understood is the effect of multiple interacting stressors during development, or how developmental responses differ between the sexes. We reared juvenile guppies of both sexes in a 2×2 design under either standard or high social housing densities, combined with the exposure to either cues of predation risk or to a control non-predator. We collected water-borne cortisol twice, first to measure initial release during a stressful event, and second to measure the change in cortisol released over time in response to a recurring stressor. We found that the sexes differed considerably in their physiological response to stress, with males releasing more cortisol for their body mass than females, and with females, but not males, reducing cortisol release over time. However, females reared at high rearing density and exposed to predation cues during early life did not habituate to the recurring stressor, suggesting that developmental experiences interact to shape the stress response. Our results emphasize the importance of studying multiple interacting factors and both sexes for studies aimed at understanding development of the stress response.
