Figure 4.

Faster aging and rejuvenating reproduction in population 2 after 2000 generations of evolution; (A) Rate of decrease in the reproductive function with age for the ancestor (grey symbol and hatched line) and five clonal isolates from population 2. The rate of decrease in the reproductive function with age (y-axis) was determined by logistic regression as described in the Methods. Isolate 2.2 declined slower and isolates 2.1, 2.3 and 2.4 declined faster than the ancestor (significant at p < 0.05. After correction for multiple testing, isolate 2.1 is significantly different from the ancestor); (B) Reproductive output (average number of progeny produced per hour over a period of twelve hours) of 204 pairs of mothers and daughters from isolate 2.1. While young mothers (2.1 young) reproduced quickly, their reproductive output at an average age of 18 hours (2.1 old) was lower. Daughters born to these mothers (2.1 daughters) reproduced quickly again. Old mothers were significantly different from young mothers and daughters (p < 0.001, after correction for multiple testing). Young mothers were not significantly different from daughters; (C) Population doubling time for the ancestor and the five isolates from population 2. The five isolates were not significantly different from one another. All error bars are standard error of the mean.