Environmental effects on growth; consequences for parents and offspring

为什么不是所有的动物都以最大可能的速度生长呢？人们早就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。虽然这些成本已被广泛记录，但很少有人试图确定其潜在机制，因此我们仍然不了解快速增长的成本是如何产生的。有人认为经济的快速增长加速了老龄化的速度，但迄今为止的证据在很大程度上还不能令人信服。通过使用一种新颖的方法来操纵生长速度，我们最近提供了这种关系的第一个严格的实验测试，并发现寿命和其他衰老指标在预测方向上发生了巨大变化，以响应生长速度的上下操纵。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的剩余时间较少的动物随后遭受更大的寿命减少。这些结果表明，虽然生长缓慢可以延缓衰老，但动物的最佳结果受到季节环境中时间限制的影响。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，都是未知的。这个项目旨在揭示这些机制，并量化它们对后代生存能力的影响，通过实验来控制刺鱼的生长速度。这是一项极具独创性的研究，它将探索生命早期遇到的不利和有利的环境条件如何在生物体细胞上留下印记，从而影响生物体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怀疑的现象，这些现象与不断变化的环境越来越相关。

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.