Testing the evolutionary theory of senescence in wild vertebrate and historical human populations

衰老，或称衰老，是当前广泛生物学学科研究的中心焦点，也是公众和政府更广泛关注的话题。由于缺乏对自然环境中衰老演化的研究，我们对导致衰老的过程的理解受到限制。自然界中的生物不可避免地面临着环境原因导致的死亡风险，这导致自然选择的力量随着年龄的增长而下降。现在人们普遍认为，衰老是这种弱化选择的双重产物。经典理论预测，增加死亡风险将导致更快的衰老速度。然而，最近的理论表明，这种预测过于简单化，可能不适用于实验室以外的地方。传统的观点还指出，随着年龄的增长，选择的力量会减弱，这使得衰老可以通过两种不同的遗传机制来进化，这两种机制被称为“拮抗多效性”和“突变积累”。然而，在包括人类在内的自然动物种群中，人们对这些机制实际扮演的角色知之甚少。我的研究将解决我们理解衰老进化的这两个主要挑战。为了了解衰老的演变，需要确定自然种群中个体死亡率、风险和衰老率的差异的原因。我将使用从四个野生脊椎动物种群的长期个体研究中收集的数据来测试共享基因和环境对成年死亡风险变化的影响。我还将测试与性别和环境质量相关的衰老速度的差异。为了测试两种被认为是导致衰老进化的遗传机制的作用，我将分析野生脊椎动物和历史人类种群的数据。我将使用人类历史数据集，对自然种群中衰老的两种遗传机制进行首次同时测试。我的分析将对有关自然界衰老进化的关键假设进行一般性的、而不仅仅是特定于系统的测试。增进我们对自然系统中衰老的理解将有利于涉及到老龄化研究的广泛的生物学学科，包括人口生态学、进化生物学、兽医和医学、分子和细胞生物学以及生理学。

Ageing, or senescence, is a central focus of current research across a wide range of biological disciplines, as well as a topic of wider public and governmental concern. Our understanding of the processes responsible for ageing is limited by the paucity of research into the evolution of senescence undertaken in natural settings. Organisms in nature experience an inevitable risk of death from environmental causes, and this leads to a decline in the force of natural selection with age. It is now widely accepted that senescence evolves as a bi-product of this weakening selection. Classical theory predicts that increasing the risk of mortality will result in the evolution of faster senescence rates. However, more recent theory has shown that this prediction is over-simplistic and may not apply outside of the laboratory. Conventional wisdom also states that the weakening force of selection with age allows senescence to evolve via two different genetic mechanisms, known as 'antagonistic pleiotropy' and 'mutation accumulation'. However, the roles that these mechanisms actually play are poorly understood in natural animal populations, including humans. My research will address these two major challenges to our understanding of evolution of senescence. Determining the causes of variation in individual mortality risk and senescence rates in natural populations is required to understand the evolution of senescence. I will use data collected from long-term individual-based studies of four wild vertebrate populations to test the effects of shared genes and environments on variation in adult mortality risk. I will also test for differences in senescence rates associated with sex and environmental quality. In order to test the roles of the two genetic mechanisms thought to be responsible for the evolution of senescence, I will analyse data from wild vertebrate and historical human populations. I will use historical human data sets to provide the first simultaneous tests of both genetic mechanisms of senescence in a natural population. My analyses will produce general, rather than just system-specific, tests of key hypotheses regarding the evolution of senescence in nature. Advancing our understanding of senescence in natural systems will benefit the wide range of biological disciplines involved in research into ageing, including population ecology, evolutionary biology, veterinary and medical sciences, molecular and cell biology and physiology.