The benefits of maternal effects in novel and in stable environments

Abstract

Natural selection favours phenotypes that match prevailing ecological conditions. A rapid process of adaptation is therefore required in changing environments. Maternal effects can facilitate such responses, but it is currently poorly understood under which circumstances maternal effects may accelerate or slow down the rate of phenotypic evolution. Here, we use a quantitative genetic model, including phenotypic plasticity and maternal effects, to suggest that the relationship between fitness and phenotypic variance plays an important role. Intuitive expectations that positive maternal effects are beneficial are supported following an extreme environmental shift, but, if too strong, that shift can also generate oscillatory dynamics that overshoot the optimal phenotype. In a stable environment, negative maternal effects that slow phenotypic evolution actually minimize variance around the optimum phenotype and thus maximize population mean fitness.

Predator-induced phenotypic plasticity within- and across-generations: a challenge for theory?

“…The negative correlation we observed between within-and across-generation responses is consistent with the model of Hoyle & Ezard [23] but only when the maternal effect coefficient is negative and the genetic covariance among reaction norm coefficients is positive. We evaluated these conditions by fitting the Hoyle & Ezard model [23] to the Daphnia maturation data from the predator and no-predator treatments of experiment 1 ( predator removal). Doing so, results in a maximum-likelihood estimate of the maternal effects coefficient that is not significantly different from zero (see the electronic supplementary material, appendix S1).…”

“…This includes the extent to which researchers impose environmental treatments that reflect ecologically relevant variation and the statistical robustness of designs that are typically used to detect transgenerational Figure 4. Fit of predicted versus observed maturation data based upon the Hoyle & Ezard model [23]. We fitted the model [23] to the Daphnia maturation data from the predator and no-predator treatments of the predator-removal experiment.…”

“…Fit of predicted versus observed maturation data based upon the Hoyle & Ezard model [23]. We fitted the model [23] to the Daphnia maturation data from the predator and no-predator treatments of the predator-removal experiment. The black (generation 2), grey (generation 3) and white (generation 4) markers indicate the results for generations 2-4.…”

“…Transgenerational responses are expected to be favoured when there is environmental heterogeneity across generations and when offspring environmental conditions are predictable from parental environmental conditions [2,3,[20][21][22]. Current theory that explicitly incorporates phenotypic plasticity and 'maternal effects' [23,24] indicates that predictable environmental variation will simultaneously select for increased plasticity within-and across-generations. However, the covariation between within-and across-generation plasticities has not yet received any empirical evaluation.…”

Coping with Change: A Closer Look at the Underlying Attributes of Change and the Individual Response to Unstable Environments

“…When the individual cannot accurately predict the environment their offspring will experience, mothers may increase within-clutch variation in offspring phenotype (bet-hedge) [105]. It is possible for maternal effects to facilitate phenotypic evolution, although it is still unclear under which circumstances this is likely to be the case [107].…”