Data from: Dietary restriction fails to extend life in stressful environments

Moderate dietary restriction often prolongs life in laboratory animals,
and this response has been interpreted as an adaptive strategy that
promotes survival during famine. However, dietary restriction can also
increase frailty, and it therefore remains unclear whether restricted
diets prolong life under stressful conditions like those experienced by
wild animals.  We manipulated adult dietary protein
of Drosophila melanogaster across a gradient of ambient
temperature and examined effects on survival. To test for trade-offs, we
also quantified the reproduction, and performance of F1, F2 and F3
descendants. We found that protein restriction increased longevity of one
or both sexes at benign ambient temperatures (25°C, 27°C) but failed to
extend longevity of flies maintained in cold (21°C, 23°C) or hot (29°C)
conditions. Instead, in females, protein restriction resulted in strongly
elevated mortality at cold temperatures. Protein restriction also
generally reduced reproductive performance and did not consistently
enhance performance of F1, F2 or F3 descendants.  Taken together,
our results challenge the long-held idea that extended longevity of
diet-restricted laboratory animals represents an adaptive survival
strategy in natural populations. Our findings suggest instead that this
response is an artefact of benign laboratory conditions, and that
DR-induced life extension might not be achieved in the more stressful
conditions experienced in the wild.

适度膳食限制（Dietary Restriction, DR）通常可延长实验动物的寿命，这一反应曾被解读为一种在饥荒时期提升生存能力的适应性策略。然而，膳食限制也会增加机体的虚弱程度，因此目前仍无法明确，在野生动物所经历的这类应激环境中，限饲饮食是否仍能延长受试个体的寿命。我们在不同环境温度梯度下，对黑腹果蝇（Drosophila melanogaster）的成年期膳食蛋白摄入水平进行调控，并检测其对果蝇生存情况的影响。为验证生存与繁殖的权衡效应，我们还量化了F1、F2及F3代后代的繁殖能力与各项生存表现。研究结果显示，在温和环境温度（25℃、27℃）下，蛋白限制可提升单性别或双性别的果蝇寿命，但在低温（21℃、23℃）或高温（29℃）环境下饲养的果蝇，其寿命并未得到延长。与之相反，在低温环境中，雌性果蝇接受蛋白限制后，死亡率会显著升高。此外，蛋白限制通常会降低果蝇的繁殖性能，且并未持续提升F1、F2及F3代后代的各项表现。综合以上结果，我们的研究对长期以来的主流观点提出了挑战：即限饲实验动物的寿命延长，代表了自然种群中的适应性生存策略。我们的研究结果反而表明，这一寿命延长现象仅是温和实验室环境下的人为产物，膳食限制诱导的寿命延长或许无法在野外更为严苛的应激环境中实现。