Department of Biology, Indiana University, Bloomington, IN 47405, USA.
Biol Lett. 2020 Mar;16(3):20200008. doi: 10.1098/rsbl.2020.0008. Epub 2020 Mar 25.
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 trade-offs between longevity and reproduction. To test this prediction, we subjected the budding yeast to 1800 generations of evolution on restricted versus non-restricted diets. Adaptation to a non-restricted diet improved reproductive fitness by 57%, but provided a much smaller (14%) advantage on a restricted diet. By contrast, adaptation to DR resulted in an approximately 35% increase in reproductive fitness on both restricted and non-restricted diets. Importantly, the life-extending effect of DR did not decrease following long-term evolution on the restricted diet. Thus, contrary to theoretical expectations, we found no evidence that the life-extending DR response became maladaptive during multigenerational DR. Together, our results suggest that the DR response has a low cost and that this phenomenon may have evolved as part of a generalist strategy that extends beyond the benefits of postponing reproduction.
饮食限制（DR）是延长生物寿命最成功和最广泛的手段。然而，DR 下寿命延长的进化基础仍然不确定。传统的进化解释是，当生物体经历 DR 时，它们会将内源性资源分配给生存，并将繁殖推迟到条件改善。然而，如果由于长寿和繁殖之间的权衡，DR 持续多代，这种延长寿命的策略应该是适应不良的。为了检验这一预测，我们让芽殖酵母在限制和非限制饮食下经历了 1800 代的进化。适应非限制饮食使生殖适应性提高了 57%，但在限制饮食中只提供了 14%的优势。相比之下，适应 DR 导致在限制和非限制饮食中生殖适应性分别提高了约 35%。重要的是，DR 的延长寿命效应在长期限制饮食进化后并没有降低。因此，与理论预期相反，我们没有发现 DR 延长寿命的反应在多代 DR 期间变得适应不良的证据。总之，我们的结果表明，DR 反应的代价很低，这种现象可能是作为一种超越推迟繁殖的好处的一般性策略的一部分而进化的。
