Low costs of adaptation to dietary restriction

Dietary restriction (DR) is the most successful and widespread means of extending organismal lifespan. However, the evolutionary basis of life extension under DR remains uncertain. The traditional evolutionary explanation is that when organisms experience DR, they allocate endogenous resources to survival and postpone reproduction until conditions improve. However, this life-extension strategy should be maladaptive if DR continues for multiple generations due to tradeoffs between longevity and reproduction. To test this prediction, we subjected the budding yeast Saccharomyces cerevisiae to 1,800 generations of evolution on restricted (i.e., DR) vs. non-restricted diets. Adaptation to a non-restricted diet improved reproductive fitness by 57% on that diet, but provided a much smaller (14%) advantage on a restricted diet. In contrast, adaptation to DR resulted in an approximately 35% increase in reproductive fitness on both restricted and non-restricted diets. Importantly, the life-extend...饮食限制（Dietary restriction，DR）是目前已知最有效且应用最广泛的个体寿命延长手段。然而，饮食限制介导的寿命延长的进化基础仍不明确。传统进化理论对此的解释为：当生物体遭遇饮食限制时，会将内源性资源优先分配至生存活动，并推迟繁殖直至环境条件改善。然而，若饮食限制持续多代，由于寿命与繁殖之间存在权衡效应，这一延寿策略将会变得适应不良。为验证这一预测，我们将出芽酵母（Saccharomyces cerevisiae）置于限制饮食（即DR）与非限制饮食环境中，进行了1800代的进化培养。对非限制饮食的适应在该饮食环境下使繁殖适合度提升了57%，但在限制饮食环境中仅带来了14%的微弱适应性优势。与之相反，对饮食限制的适应则使得生物体在限制与非限制两种饮食环境下的繁殖适合度均提升了约35%。值得注意的是，其延寿……