The role of stress in natural populations

生存的基本现实之一是需要应对压力。它每天都会影响我们所有人，会损害健康，增加死亡率，并会加速衰老。自然界中的动物可能也会受到类似的影响，尽管它们能巧妙地适应许多应激源。应激轴是神经内分泌系统的关键部分，它整合了环境变化，并通过它实现了繁殖、生长或储存能量的生活史决定。当今最活跃的研究领域之一是神经科学领域，特别是压力如何影响大脑和身体。事实上，所有这些研究都建立在实验室大鼠和小鼠模型的基础上，但在自然界中，存在的问题有许多解决方案。我的研究计划的目的是运用关于压力作用的实验室研究结果，以帮助了解现实世界中动物在应对压力情况时的适应能力，当这些适应能力不足时会发生什么(即当慢性自然应激源通过母体效应对生理、生殖、大脑组织和人口统计产生负面影响时)，以及应激反应的变化可以多快演变。因此，尽管我的发现可能也与人类的状况有关，但我的主要动机是了解应激轴在为动物在自然界中的生存做准备方面所起的作用，以及应激源如何改变它们的反应。考虑到由于全球变暖而发生的快速变化，这一点在北方尤其相关。我的研究在加拿大各地进行，包括育空地区，并建立在我对野生哺乳动物的丰富经验的基础上。它针对五个关键领域，1)慢性应激对母体编程的作用和应激轴的表观遗传变化；2)应激对人口统计学的影响；3)应激轴对生殖成功的影响；4)肾上腺在与冬季生存相关的生活史过程中的作用(空间行为和冬眠)；以及5)应激轴的演变。

One of the fundamental realities of existence is the need to cope with stress. It impacts us all daily, can compromise health, increase the rates of mortality, and can accelerate the rate of aging. Animals in nature may be similarly affected, though they are exquisitely adapted to deal with many stressors. The stress axis is a pivotal part of the neuroendocrine system that integrates environmental change and through which life history decisions to reproduce, to grow, or to put energy into storage are implemented. One of the most vigorous areas of research today is the field of neuroscience and particularly how stress impacts the brain and body. Virtually all this research rests on a foundation of the laboratory rat and mouse models, yet in nature there are many solutions to the problem of existence. The objective of my research program is to bring to bear laboratory findings on the role of stress to help to understand the adaptations that animals in real world have in coping with stressful situations, what happens when these are insufficient (i.e. when chronic natural stressors negatively impact physiology, reproduction, brain organization, and demography through maternal effects), and how rapidly changes in the stress response can evolve. Thus though my findings may also have relevance to the human condition, my primary motivation is to understand the role of the stress axis in equipping animals for life in the natural world and how stressors modify their response. This is particularly relevant in the north, given the rapid changes occurring there because of global warming. My research takes place throughout Canada, including the Yukon, and builds on my extensive experience with wild mammals. It targets five key areas 1) the role of the chronic stress on maternal programming and epigenetic changes in the stress axis; 2) the impact of stress on population demography; 3) the impact of stress axis on reproductive success; 4) the role of the adrenals in life history processes associated with winter survival (spacing behavior and hibernation); and 5) the evolution of the stress axis.