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Effects of semi-natural environmental conditions on phenotypic plasticity in Rattus norvegicus

  • Author(s): Margerum, Lisa
  • Advisor(s): Francis, Darlene
  • Kaufer, Daniela
  • et al.
Abstract

Controlled laboratory experiments find there is normal variation in maternal care that regulates the development of the endocrine, cognitive and behavioral responses to stress in rats. As housing conditions of laboratory rats can have pronounced effects on experimental outcomes, I examined how semi-naturalistic environmental conditions affect maternal care and how or if variation in maternal care affects neural and behavioral development in adult female offspring. Specifically, I assessed maternal behaviors in semi-natural enclosures and what effects, if any, alternative maternal strategies might have on the development of stress physiology and cognition in adult offspring. I found semi-natural housing conditions decreased variation in maternal care, litter size, and offspring survival regardless of the amount of maternal care provided to pups, but increased pregnancy success in dams phenotyped as lower maternal care providers in laboratory housing, suggesting there could be direct fitness benefits to providing lower levels of maternal care. I also found significant environmental effects on adult offspring stress reactivity and behavior as well as cognition and hippocampal cell proliferation that are not mediated by maternal care, unlike previous laboratory findings. Collectively these analyses underscore the critical role of environmental context on maternal behavior and its behavioral and physiological outcomes

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