Endocrine responses to environmental variation

Understanding the proximate mechanisms regulating the individual variation in responses to environmental challenges and changes is fundamental in ecological and evolutionary research. Theory predicts correlations between behavioural, cognitive and neurophysiological traits to form alternative strategies named coping styles. The “proactive strategy” combines a general fight-or-flight response and inflexibility in learning with a relatively low HPA (hypothalamic–pituitary–adrenal) response. The “reactive strategy” includes risk aversion, flexibility in learning and an enhanced HPA response. Most studies measured differences in endocrine response in populations that were artificially selected for their personality or cognitive traits. Those that considered wild or unselected populations, suggest a more complex relationship between behaviour, cognition and physiology.

I tested the predictions of the coping style model in an unselected population of bank voles (Myodes glareolus). I examined the relationship between a measure of endocrine state (concentrations of faecal glucocorticoid metabolites), two behavioural traits (boldness and activity) and two cognitive traits (speed and flexibility of learning) under three different conditions.

Individuals were moderately consistent in their HPA response across situations. Proactive voles had significantly lower corticosterone levels than reactive conspecifics in indoor and outdoor conditions. However, I could not find any co-variation between cognitive and behavioural traits and corticosterone levels in the open field test. Results partially support the original coping style model but highlight the need for further investigations and testing of theory.

Collaborators: J.A. Eccard (UniPotsdam), M. Dammhahn (UniPotsdam, Germany), J. Jacob (Julius Kühn Institute, Münster, Germany), R. Palme (UniVienna, Austria), M. Zaccaroni (UniFirenze, Italy)

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