Le Galliard Jean-François, Clobert Jean, Ferrière Régis
Laboratoire Fonctionnement et Evolution des Systèmes Ecologiques, CNRS UMR 7625, Ecole Normale Supérieure, 46 rue d'Ulm, 75230 Paris cedex 05, France.
Nature. 2004 Nov 25;432(7016):502-5. doi: 10.1038/nature03057.
Strong evidence for a genetic basis of variation in physical performance has accumulated. Considering one of the basic tenets of evolutionary physiology--that physical performance and darwinian fitness are tightly linked--one may expect phenotypes with exceptional physiological capacities to be promoted by natural selection. Why then does physical performance remain considerably variable in human and other animal populations? Our analysis of locomotor performance in the common lizard (Lacerta vivipara) demonstrates that initial endurance (running time to exhaustion measured at birth) is indeed highly heritable, but natural selection in favour of this trait can be unexpectedly weak. A manipulation of dietary conditions unravels a proximate mechanism explaining this pattern. Fully fed individuals experience a marked reversal of performance within only one month after birth: juveniles with low endurance catch up, whereas individuals with high endurance lose their advantage. In contrast, dietary restriction allows highly endurant neonates to retain their locomotor superiority as they age. Thus, the expression of a genetic predisposition to high physical performance strongly depends on the environment experienced early in life.
关于身体机能变异存在遗传基础的有力证据已经积累起来。考虑到进化生理学的一个基本原理——身体机能与达尔文适应性紧密相连——人们可能会预期具有非凡生理能力的表型会受到自然选择的推动。那么，为什么在人类和其他动物群体中，身体机能仍然存在相当大的变异性呢？我们对普通蜥蜴（胎生蜥蜴）运动表现的分析表明，初始耐力（出生时测量的力竭奔跑时间）确实具有高度遗传性，但有利于该性状的自然选择可能出人意料地微弱。对饮食条件的操控揭示了一个解释这种模式的直接机制。完全饱腹的个体在出生后仅一个月内就经历了运动表现的显著逆转：耐力低的幼体赶了上来，而耐力高的个体失去了优势。相比之下，饮食限制使高耐力的新生儿在成长过程中能够保持其运动优势。因此，高身体机能遗传倾向的表达强烈依赖于生命早期所经历的环境。
