Strain variation in mean lifespan of ILSXISS recombinant inbred (RI) mice under ad libitum (AL) and dietary restriction (DR) diets. Lifespans were typically obtained from 10 AL and 10 DR mice from each strain (5 males & 5 females per treatment group); sample sizes in a few strains were either greater or less than 10 (details in Supplementary Table S1). The mean lifespans in the upper two panels are shown for each strain [AL (□) and DR (■)], ranked in ascending order according to the AL means (A: males, 41 strains; B: females, 39 strains). The lower two panels illustrate the deviation (positive and negative) of the mean DR lifespan from the mean AL for the same strains, ranked from the strain with the greatest increase in lifespan under DR to the strain with the greatest decrease (C: males; D: females). Error bars represent SEM. * p < 0.05, ** p < 0.01, *** p < 0.001 by t-test (no experiment-wise Bonferroni correction).