Behaviour 2019
Neuroendocrine Mechanisms of Individual Variation in Behavioral Phenotypes
Sarah E. Westrick1,2, Freya van Kesteren2, Stan Boutin3, Jeffrey E. Lane4, Andrew G. McAdam5, Ben Dantzer2. 1University of Illinois at Urbana-Champaign, Urbana, IL, United States; 2University of Michigan, Ann Arbor, MI, United States; 3University of Alberta, Edmonton, Alberta, Canada; 4University of Saskatchewan, Saskatoon, Saskatchewan, Canada; 5University of Colorado, Boulder, CO, United States

Individual variation is the fundamental substrate on which natural selection, and by extension adaptive evolution, depends. Developmental plasticity caused by variation in early life experiences, particularly parental care, is an important route by which individual differences can emerge. The impact of maternal physiology and behavior on offspring may be particularly pronounced in mammals due to the extended period of offspring dependency. Our goal was to understand how the maternal hormonal environment produces individual variation in behavior and neuroendocrine responses in a free-ranging small mammal, the North American red squirrel. We provisioned pregnant or lactating mothers daily with cortisol to experimentally elevate circulating glucocorticoids. We then compared two personality traits, the reactivity and negative feedback of the hypothalamus-pituitary-adrenal axis, and brain gene expression between the offspring of control and treated mothers. Together, these studies inform our understanding of the transgenerational transmission of environmental information and the development of individual variation in behavior through maternal hormones.