Effects of selfing and outcrossing on transgenerational responses to predation risk

Phenotypic plasticity, an organism’s ability to change traits in response to its environment, can improve an individual's fitness by promoting a phenotype better suited for current environmental conditions. Phenotypic expression can be altered by direct experiences (i.e., within-generation plasticity) or experiences of previous generations (i.e., transgenerational plasticity). Transgenerational plasticity can help offspring overcome environmental stressors, such as predation, using epigenetic information from their parent(s). Offspring typically receive information from two parents though simultaneous hermaphrodites can produce offspring with varied contributions of epigenetic information by reproducing via outcrossing or self-fertilization (i.e., selfing). While the impact of predation on transgenerational effects has been described, the relative influence of epigenetic information from one or two parental sources is unknown. This study aimed to determine how transgenerational epigenetic effects of predation risk are influenced by selfing and outcrossing. Physid snails were collected and reared over two generations to evaluate anti-predator behavior and shell morphology. The F₁ generation was exposed to treatments consisting of all combinations of predation risk and a mate's absence or presence, resulting in six F₂ generation treatment lineages. Shell morphometrics and a behavioral assay were completed to quantify the anti-predator response of the F₂ generation. We found that the offspring of outcrossers were larger, and their size was influenced by paternal predator treatment. F₂ snails were also less likely to exhibit anti-predator behavior after exposure to predation risk. These findings provide insights into our understanding of transgenerational effects in species with various reproductive strategies.