Figure 1.

Experimental design. (a) The experiment included eight experimental evolution lines; four from the E-regime (early reproduction; salmon) and four from the L-regime (late reproduction; green). The E-regime was propagated by harvesting eggs laid after only 2 days of adult reproduction, whereas the L-regime was propagated by providing individuals that had aged 10 days with host seeds and harvesting the eggs. The E- and L-regimes had been kept for 350 and 240 generations, respectively, prior to the experiment. (b) Females from all lines, that were either young (1–3 days) or aged (6–8 days), were mated to standard males from the base population and allowed to lay eggs for 48 h. The males were either serving as controls or they had been irradiated to generate a damaged ejaculate. Offspring resulting from the matings to control males were counted to estimate the age-dependent reproductive schedules of the F0 females in the experiment. (c) F1 offspring were crossed within the line and treatment group (while avoiding inbreeding) using a middle-class neighbourhood (MCN) design to relax selection against induced (epi)mutations. Counts of emerging F2 adult offspring were used to assess age-specific female germline maintenance by comparing the proportional reduction in offspring quality in lineages deriving from either young and aged F0 females, mated with either irradiated or control males. Photo credit for panel (b): Mareike Koppik. Beetles in panel (c) were generated using BioRender.