The influence of maternal aging on mixis induction in various generations of marine Brachionus rotifers

Aging is a significant internal factor influencing the sexual ability of rotifers. This study examined the effects of maternal aging on a rotifer's reproductive behavior (either sexual or asexual) and how the impacts were transmitted via generations (P − F1 − F2) in two marine species in the Brachionus plicatilis species complex: Brachionus plicatilis (large type) and Brachionus rotundiformis (super-small type). Based on the rotifer reproductive period, we established young and old lineages produced in the first and second halves of the period, respectively. The fecundity and longevity of the progeny in the two species and throughout the generations remained unaffected by maternal age. However, young amictic females in each species (especially in B. plicatilis) produced a larger ratio of mictic offspring. The multigenerational assessment revealed that the amictic offspring from old mothers produced more mictic daughters than those from young rotifers. This implies that aged rotifers may adopt an adaptive strategy (i.e., entering dormancy via sexual reproduction) for survival.