Duration of heat stress determines whether stopping or continuing reproduction is the advantageous strategy.
Curves represent the fraction of plates (each containing offspring of a single stressed individual) that have exhausted bacterial food and thus finished the “eating race”. Because all plates initially contained equal amounts of bacteria, plates that were consumed faster contained more offspring. Depending on the duration of the stress, (A) 12 and (B) 24 hours, winning strategies were continued reproduction (worms stressed at 29°C continued to lay eggs) or cessation (worms stressed at 31°C did not ovulate or lay eggs). Time is in hours. The difference between the two curves was suggestive, although not significant in panel A (Kolmogorov-Smirnov test p = 0.13) and significant in panel B (p = 1.7×10−4).