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...