Predator-induced transgenerational plasticity in animals: a meta-analysis

Abstract

There is growing evidence that the environment experienced by one generation can influence phenotypes in the next generation via transgenerational plasticity (TGP). One of the best-studied examples of TGP in animals is predator-induced transgenerational plasticity, whereby exposing parents to predation risk triggers changes in offspring phenotypes. Yet, there is a lack of general consensus synthesizing the predator-prey literature with existing theory pertaining to ecology and evolution of TGP. Here, we apply a meta-analysis to the sizable literature on predator-induced TGP (441 effect sizes from 29 species and 49 studies) to explore five hypotheses about the magnitude, form and direction of predator-induced TGP. Hypothesis #1: the strength of predator-induced TGP should vary with the number of predator cues. Hypothesis #2: the strength of predator-induced TGP should vary with reproductive mode. Hypothesis #3: the strength and direction of predator-induced TGP should vary among offspring phenotypic traits because some traits are more plastic than others. Hypothesis #4: the strength of predator-induced TGP should wane over ontogeny. Hypothesis #5: predator-induced TGP should generate adaptive phenotypes that should be more evident when offspring are themselves exposed to risk. We found strong evidence for predator-induced TGP overall, but no evidence that parental predator exposure causes offspring traits to change in a particular direction. Additionally, we found little evidence in support of any of the specific hypotheses. We infer that the failure to find consistent evidence reflects the heterogeneous nature of the phenomena, and the highly diverse experimental designs used to study it. Together, these findings set an agenda for future work in this area.

Keywords: Developmental plasticity; Intergenerational inheritance; Maternal effect; Parental effect; Predation.

Fig. 1

Orchard plots showing the overall a direction of Predator-induced TGP effects (Hedge’s g), as well as b the effect of Predator-induced TGP on trait variance (lnCVR, values > 0 represent datapoints where treatment group variance exceeded control group variance). Model estimates ± SE are depicted as overlaid black open circles ± thick bar, with a thin bar representing the prediction intervals. Dashed line indicates zero (i.e. no effect) and k values indicate the number of effect sizes

Fig. 2

Forest plot showing the influence of the type of offspring trait measured on Predator-induced TGP (N = 441 effect sizes). Model estimates ± 95% CIs are depicted as points and bars with arrows. The size of the estimate point relates to the precision of the point (1/SE)

Fig. 3

Forest plot showing influence of offspring risk environment on Predator-induced TGP (N = 149 effect sizes, from 13 studies). Model estimates ± 95% CIs are depicted as points and bars with arrows. The size of the estimate point relates to the precision of the point (1/SE)