%0 Journal Article %A T.M. Houslay %A R.L. Earley %A S.J. White %A W. Lammers %A A.J. Grimmer %A L.M. Travers %A E.L. Johnson %A A.J. Young %A A.J. Wilson %T Genetic integration of the stress response %D 2019 %R 10.1101/770586 %J bioRxiv %P 770586 %X The stress response is a product of selection for an integrated suite of behavioural and physiological traits that facilitate coping with acute stressors. As such, genetic variation in the stress response is expected to reflect genetic variation in, and genetic covariation among, its behavioural and physiological components. Such genetic integration among stress response components has yet to be formally demonstrated using multivariate quantitative genetics, despite its profound implications for optimising human and animal health and understanding the responses of wild populations to natural and anthropogenic stressors. Here we use a laboratory population of wild-derived Trinidadian guppies (Poecilia reticulata) to determine levels of genetic variation in behavioural and physiological components of the acute stress response, and to establish whether such variation is integrated into a single major axis of genetic (co)variation. First, using a novel method to characterise behavioural components of the stress response from a widely used Open Field Trial paradigm, we find genetic variation in, and genetic covariation among, behavioural parameters that characterise movement patterns under stress. Second, we find a strong genetic component to variation in both the endocrine response to a confinement stressor and the rate at which this response attenuates following repeated exposures to the stressor. Finally, we show that these behavioural and physiological components of the stress response align on a major axis of genetic (co)variation as predicted, suggesting correlational selection in the past has led to genetic integration. This genetic integration could either facilitate or constrain future responses to selection, depending upon the extent to which the direction of selection aligns with this major axis of genetic covariation among stress response traits. This genetic integration also suggests that, while stress-related disease typically arises from physiological stress responses, selection on the genetically correlated behavioural responses could offer a viable non-invasive route to the genetic improvement of health and welfare in captive animal populations. %U https://www.biorxiv.org/content/biorxiv/early/2019/09/16/770586.full.pdf