Fig. 2

Decline in mean productivity of experimental lines during mutation accumulation with subsequent increase in productivity during population expansion. Fitness (productivity) trajectories of five experimental evolution lines of C. elegans during two experimental phases of (a) mutation accumulation, and (b) fitness recovery after population expansion. Two fitness assays were conducted during the mutation accumulation phase of the experiment — (i) following 24 consecutive generations of mutation accumulation with msh-2 RNAi (MA24), and (ii) 50 consecutive generations of mutation accumulation with msh-2 RNAi and an additional 15 additional generations of full-sib mating to promote homozygosity (MA50 + 15 Inbreeding). All five experimental lines displayed significant decline in productivity, a fitness-related trait during the MA phase, relative to the ancestral pre-MA control from which all lines were derived. Populations derived from the MA lines exhibited moderate to strong fitness recovery following 150 consecutive generations of maintenance at large population sizes (RC150). Each point for the assay RC150 represents the mean productivity across five independently expanded population and within population replicates (5 populations × 5 replicates per population). The mean productivity of the ancestral pre-mutation accumulation control has been scaled to a value of 1. Errors bars represent one standard error