Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK.
School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK.
Proc Biol Sci. 2021 Jul 28;288(1955):20210851. doi: 10.1098/rspb.2021.0851. Epub 2021 Jul 21.
Patterns of ageing across the tree of life are much more diverse than previously thought. Yet, we still do not adequately understand how, why and where across the tree of life a particular pattern of ageing will evolve. An ability to predict ageing patterns requires a firmer understanding of how and why different ecological and evolutionary factors alter the sensitivity of fitness to age-related changes in mortality and reproduction. From this understanding, we can ask why and where selection gradients might not decline with age. Here, we begin by summarizing the recent breadth of literature that is unearthing, empirically and theoretically, the mechanisms that drive variation in patters of senescence. We focus on the relevance of two key parameters, population structure and reproductive value, as key to understanding selection gradients, and therefore senescence. We discuss how growth form, individual trade-offs, stage structure and social interactions may all facilitate differing distributions of these two key parameters than those predicted by classical theory. We argue that these four key aspects can help us understand why patterns of negligible and negative senescence can actually be explained under the same evolutionary framework as classical senescence.
生命之树上的衰老模式比以前想象的要多样化得多。然而，我们仍然不能充分理解为什么以及在生命之树上的什么地方，特定的衰老模式会进化。预测衰老模式的能力需要更深入地了解不同的生态和进化因素如何改变适应与死亡率和繁殖率相关的年龄变化的敏感性。从这个理解中，我们可以问为什么以及在哪里选择梯度可能不会随着年龄的增长而下降。在这里，我们首先总结了最近大量的文献，这些文献从经验和理论上揭示了导致衰老模式变化的机制。我们专注于两个关键参数的相关性，即种群结构和生殖价值，这是理解选择梯度，因此也是衰老的关键。我们讨论了生长形式、个体权衡、阶段结构和社会相互作用如何都可能导致这两个关键参数的分布与经典理论预测的不同。我们认为，这四个关键方面可以帮助我们理解为什么在与经典衰老相同的进化框架下，实际上可以解释微不足道的和负面的衰老模式。
