Martin Lynn B, Weil Zachary M, Nelson Randy J
Departments of Psychology and Neuroscience, The Ohio State University, Columbus, OH 43210, USA.
Philos Trans R Soc Lond B Biol Sci. 2008 Jan 27;363(1490):321-39. doi: 10.1098/rstb.2007.2142.
Animals living in temporally dynamic environments experience variation in resource availability, climate and threat of infection over the course of the year. Thus, to survive and reproduce successfully, these organisms must allocate resources among competing physiological systems in such a way as to maximize fitness in changing environments. Here, we review evidence supporting the hypothesis that physiological trade-offs, particularly those between the reproductive and immune systems, mediate part of the seasonal changes detected in the immune defences of many vertebrates. Abundant recent work has detected significant energetic and nutritional costs of immune defence. Sometimes these physiological costs are sufficiently large to affect fitness (e.g. reproductive output, growth or survival), indicating that selection for appropriate allocation strategies probably occurred in the past. Because hormones often orchestrate allocations among physiological systems, the endocrine mediators of seasonal changes in immune activity are discussed. Many hormones, including melatonin, glucocorticoids and androgens have extensive and consistent effects on the immune system, and they change in systematic fashions over the year. Finally, a modified framework within which to conduct future studies in ecological immunology is proposed, viz. a heightened appreciation of the complex but intelligible nature of the vertebrate immune system. Although other factors besides trade-offs undoubtedly influence seasonal variation in immune defence in animals, a growing literature supports a role for physiological trade-offs and the fitness consequences they sometimes produce.
生活在时间动态环境中的动物，在一年的过程中会经历资源可用性、气候和感染威胁的变化。因此，为了成功生存和繁殖，这些生物必须在相互竞争的生理系统之间分配资源，以便在不断变化的环境中最大化适应性。在这里，我们回顾了支持以下假设的证据：生理权衡，特别是生殖系统和免疫系统之间的权衡，介导了许多脊椎动物免疫防御中检测到的部分季节性变化。最近大量的研究发现了免疫防御存在显著的能量和营养成本。有时这些生理成本足够大，会影响适应性（例如繁殖输出、生长或生存），这表明过去可能发生了对适当分配策略的选择。由于激素通常协调生理系统之间的分配，因此讨论了免疫活动季节性变化的内分泌介质。许多激素，包括褪黑素、糖皮质激素和雄激素，对免疫系统有广泛且一致的影响，并且它们在一年中以系统的方式变化。最后，提出了一个用于未来生态免疫学研究的改进框架，即提高对脊椎动物免疫系统复杂但可理解本质的认识。尽管权衡之外的其他因素无疑会影响动物免疫防御的季节性变化，但越来越多的文献支持生理权衡及其有时产生的适应性后果所起的作用。
