Dietary restriction and aging: Comparative tests of evolutionary hypotheses

Dietary restriction (DR) increases life span in many types of animals. The response to chronic DR may be an adaptation to environments with variable f ood levels. This study uses the comparative method to test evolutionary pre dictions about the origin of the response to DR, using data from 10 species of rotifers. Most species, but not all, responded to DR by increasing mean life span, maximum life span, reproductive life span, mortality rate doubl ing time, and initial mortality rate. Interspecific comparisons did not sho w the predicted correlations between the strength of the response to DR and either reproductive life span, age of first reproduction, or total reprodu ction. There was support for the idea that the response to chronic DR is as sociated with changes in reproductive allocation during short-term periods of starvation: species that reduced reproduction when starved increased the ir life spans under DR, whereas species that continued to reproduce when st arved decreased their life spans under DR.