Predator-induced transgenerational plasticity of parental care behaviour in male three-spined stickleback fish across two generations.

Parental care is a critical determinant of offspring fitness, and parents adjust their care in response to ecological challenges, including predation risk. The experiences of both mothers and fathers can influence phenotypes of future generations (transgenerational plasticity). If it is adaptive for parents to alter parental care in response to predation risk, then we expect F and F offspring who receive transgenerational cues of predation risk to shift their parental care behaviour if these ancestral cues reliably predict a similarly risky environment as their F parents. Here, we used three-spined sticklebacks () to understand how paternal exposure to predation risk prior to mating alters reproductive traits and parental care behaviour in unexposed F sons and F grandsons. Sons of predator-exposed fathers took more attempts to mate than sons of control fathers. F sons and F grandsons with two (maternal and paternal) predator-exposed grandfathers shifted their paternal care (fanning) behaviour in strikingly similar ways: they fanned less initially, but fanned more near egg hatching. This shift in fanning behaviour matches shifts observed in response to direct exposure to predation risk, suggesting a highly conserved response to pre-fertilization predator exposure that persists from the F to the F and F generations.