Environmental effects on growth; consequences for parents and offspring

为什么所有动物都不能以最大可能的速度生长呢？长期以来，人们认识到动物有可能比正常情况下生长得更快，而这种限制的原因被认为是快速生长的延迟成本的存在。虽然这些成本已经被广泛记录在案，但几乎没有人试图确定潜在的机制，因此我们仍然不明白快速增长的成本是如何产生的。有人提出，快速增长会加速老龄化，但到目前为止，证据在很大程度上并不令人信服。通过使用一种新的方法来操纵增长率，我们最近对这种关系进行了第一次严格的实验测试，并发现随着增长率的向上和向下操纵，寿命和其他衰老指标在预测方向上都发生了戏剧性的变化。此外，这些影响的强度取决于在繁殖季节之前从生长扰动中恢复的可感知时间：对于给定的生长速度，在繁殖季节开始之前有较少空闲时间的动物随后遭受更大的寿命缩短。这些结果表明，虽然生长较慢可以延缓衰老，但在季节性环境中，动物的最佳结果受到时间限制的影响。然而，这些戏剧性效应背后的生理机制，以及它们如何影响后代的健康，目前尚不清楚。该项目旨在通过操纵刺鱼生长速度的实验，揭示这些机制，并量化它们对后代生存能力的影响。这是一项极具原创性的研究，将探索生命早期遇到的不利和有利的环境条件如何在有机体细胞上留下印记，从而影响其晚年开始衰老的速度，并可能影响其后代的命运。它旨在解释生态学家长期以来怀疑的现象，这些现象在不断变化的环境中具有越来越大的相关性。

Why don't animals all grow at their maximum possible rate? It has long been recognised that animals have the potential to grow faster than they normally do, and the reason for this restraint is thought to be the existence of delayed costs of rapid growth. While such costs have been widely documented, there has been little attempt to determine the underlying mechanisms, so we still do not understand how the costs of rapid growth are incurred. It has been suggested that rapid growth hastens the rate of ageing, but the evidence so far has largely been unconvincing. By using a novel approach to manipulate growth rates, we recently provided the first rigorous experimental test of this relationship, and found dramatic changes in both lifespan and other measures of senescence in the predicted direction in response to both upward and downward manipulations of growth rates. Moreover, the strength of these effects depended on the perceived time available to recover from the growth perturbation prior to the breeding season: for a given rate of growth, animals with less time to spare before the start of the breeding season subsequently suffered a greater reduction in their lifespan. These results demonstrate that, while growing more slowly can postpone senescence, the best outcome for the animal is influenced by time constraints in a seasonal environment. However the physiological mechanisms underlying these dramatic effects, and how they influence offspring fitness, are unknown. This project aims to uncover those mechanisms, and to quantify their effect on offspring viability, using experiments that manipulate the growth rate of stickleback fish. This is a highly original study that will explore how adverse and favourable environmental conditions encountered early in life can leave an imprint on an organism's cells that influence both the rate at which it starts to senescence later in life, and potentially the fate of its offspring. It aims to explain phenomena long suspected by ecologists, which have increasing relevance in a changing environment.