Like mother, like daughter: heritability of female Richardson’s ground squirrel Urocitellus richardsonii cortisol stress responses

Abstract

Activation of the hypothalamic–pituitary–adrenal (HPA) axis liberates glucocorticoids, which provides an acute indication of an individual’s response to stressors. The heritability of the stress response in wild mammals, however, remains poorly documented. We quantified the cortisol stress response of female Richardson’s ground squirrels (RGSs) to handling and physical restraint, testing for: (1) the effects of individual age, time of day, and sample latency; (2) repeatability within individuals; (3) narrow-sense heritability; and (4) differences among individuals owing to potential genetic and/or environmental effects. We detected a positive linear relationship between baseline plasma cortisol (BL-cortisol) concentration and stress-induced plasma cortisol (SI-cortisol) concentration that defined each individual’s cortisol stress response. BL-cortisol, SI-cortisol, and stress response did not differ according to the time the sample was taken, or by subject age. Cortisol stress response was highly repeatable within individuals, had a mother–offspring heritability of h2 = 0.40 ± 0.24 (mean ± SE), full-sibling heritability of hFS2 = 0.37 ± 0.71, and half-sibling heritability of hHS2= 0.75 ± 1.41. Stress responses of sibling groups, immediate-family groups, and squirrels within a given area did not differ, whereas those of individuals from more distantly related matrilines did. Our results highlight the natural variability in HPA axis reactivity among individuals by quantifying both BL- and SI-cortisol levels, demonstrate partial heritability of the stress response that is not attributable to environmental variation, and suggest that at least part of an individual’s stress response can be accounted for by differences in matrilineal history.

Prenatal Exposure to High Cortisol Induces ADHD-like Behaviors with Delay in Spatial Cognitive Functions during the Post-weaning Period in Rats

“…High cortisol level was critically associated with weight loss in animal models showing depressive symptoms that were induced by repetitive corticosterone injections [ 9 , 10 ]. Consistent with those reports, we also confirmed the weight loss in Corti.Moms during pregnancy and postnatal Corti.Pups, suggesting that maternal cortisol level during pregnancy might influence the cortisol level in offspring ( Fig.…”

Individual variation in phenotypic plasticity of the stress axis

“…More broadly, it is unclear whether individual differences in endocrine plasticity arise 211 from genetic, early-life, or environmental effects. Circulating glucocorticoids are shaped in part 212 by additive genetic effects [44][45][46][47], though the heritability of plasticity in glucocorticoids has not 213 been examined [18]. Early life exposure to fluctuating environments [48], maternal 214 glucocorticoids [49], and reduced parental care [50] all shape the glucocorticoid phenotype of 215 offspring [51][52][53], and could similarly shape variation in endocrine plasticity.…”

Gone girl: Richardson's ground squirrel offspring and neighbours are resilient to female removal

“…Furthermore, Bairos-Novak et al . [73] recently demonstrated that variation in the cortisol-based stress response of Richardson's ground squirrels is attributable more to heritability than environmental influences, suggesting that their physiological stress response may be more robust to external stressors than previously assumed. We attempted to collect faecal samples for glucocorticoid metabolite analysis from a variety of neighbours, though we observed that individuals vary in their ‘trapability'.…”