Parental stressor exposure simultaneously conveys both adaptive and maladaptive larval phenotypes through epigenetic inheritance in the zebrafish (Danio rerio)

Abstract

Genomic modifications occur slowly across generations, whereas short-term epigenetic inheritance of adaptive phenotypes may be immediately beneficial to large numbers of individuals acting as a bridge for survival when adverse environments occur. Crude oil was used as an example of an environmental stressor. Adult zebrafish (P0) were dietarily-exposed for three weeks to no, low, medium or high concentrations of crude oil. The F1 offspring obtained from the P0 groups were then assessed for transgenerational epigenetic transfer of oil-induced phenotypes. The exposure did not alter body length, body and organ mass or condition factor in the P0. However, when the P0 were bred, the fecundity in both sexes decreased in proportion to the amount of oil fed. Then the F1 larvae from each P0 were exposed from hatch to 5dpf to oil in their ambient water. Remarkably, F1 larvae derived from oil-exposed parents, when reared in oiled water, showed a 30% enhanced survival compared to controls (P<0.001). Unexpectedly, from day 3 to 5 of exposure, the F1 larvae from oil-exposed parents showed poorer survival in clean water (up to 55 % decreased survival). Additionally, parental oil exposure induced bradycardia (presumably maladaptive) in F1 larvae in both clean and oiled water. We conclude that epigenetic transgenerational inheritance can lead to an immediate and simultaneous inheritance of both beneficial and maladaptive traits in a large proportion of the F1 larvae. Depending upon whether they are offset by the maladaptive traits, the adaptive responses may help fish populations survive when facing transient environmental stressors.