Age-dependent effects of predation risk on reproductive success in a freshwater snail

Abstract

Reproductive performance is often age-dependent, showing patterns of improvement and/or senescence as well as trade-offs with other traits throughout the lifespan. High levels of extrinsic mortality (e.g., from predators) have been shown to sometimes, but not always, select for accelerated actuarial senescence in nature and in the lab. Here, we explore the inductive (i.e., plastic) effects of predation risk (i.e., nonlethal exposure to chemical cues from predators) on the reproductive success of freshwater snails (Physa acuta). Snails were reared either in the presence or absence of chemical cues from predatory crayfish and mated early in life or late in life (a 2 × 2 factorial design); we measured egg hatching and early post-hatching survival of their offspring. Both age and predation risk reduced reproductive success, illustrating that predation risk can have a cross-generational effect on the early survival of juveniles. Further, the decline in reproductive success was over three times faster under predation risk compared to the no-predator treatment, an effect that stemmed from a disproportionate, negative effect of predation risk on the post-hatching survival instead of hatching rate. We discuss our results in terms of a hypothesized consequence of elevated stress hormone levels.

Offspring reaction norms shaped by parental environment: interaction between within- and trans-generational plasticity of inducible defenses

“…However, the decrease in weight in offspring from induced parents may also be a transgenerational cost, and resulting from a higher investment of parents in defenses than in progeny. Predation risk is indeed known to affect the decision making of prey between predation avoidance and energy intake, and to increase the maternal stress acting on offspring development [ 50 , 57 , 58 ]. These results further suggest that offspring cannot totally overcome the parental environment effect because TGP was detected late in offspring development.…”

“…In this study, we conducted an experimental two-generation study to investigate how WGP and TGP can interact to shape the inducible defenses of the freshwater snail Physa acuta (behaviour and shell morphology) in response to predator cues. The hermaphroditic Physa gastropods have been used in numerous works studying inducible defenses (e.g., DeWitt [ 37 ]; DeWitt et al, [ 47 ]; Auld & Relyea [ 48 ]; Gustafson et al, [ 49 ]; Auld & Houser [ 50 ]; Beaty et al, [ 42 ]). Modifications of shell morphology and behaviour induced by predator cues are thus well-described (shell-crushing resistant: e.g., thicker shell, rotund shell shape and predator avoidance behaviour).…”

Transgenerational plasticity of inducible defences: Combined effects of grand‐parental, parental and current environments

“…We focused on a hermaphroditic gastropod Physa acuta (Figure ). Physidae are well‐known to develop adaptive phenotypes in response to predation risk (Auld & Houser, ; Auld & Relyea, , ; Beaty et al, ; DeWitt, Sih, & Hucko, ; Gustafson, Kensinger, Bolek, & Luttbeg, ). Predator (crayfish) cues induce within‐generational plasticity of Physa sp.…”

Transgenerational plasticity of inducible defenses: combined effects of grand-parental, parental and current environments

“…We focused on a hermaphroditic gastropod Physa acuta. Physidae are well-known to develop adaptive phenotypes in response to predation risk (DeWitt et al 1999;Relyea 2008, 2011;Gustafson et al 2014;Auld and Houser 2015;Beaty et al 2016). Predator (crayfish) cues induce WGP of Physa sp.…”