Maternal effects and evolution at ecological time-scales

1. Genetic and environmental maternal effects can play an important role in the evolutionary dynamics of a population: they may have a substantial impact on the rate and direction of genetic change in response to selection, and they may generate immediate phenotypic change via phenotypic plasticity. Because of this potential to generate rapid phenotypic change in a population, maternal effects may be particularly important for evolution at ecological time-scales. 2. Despite an increased interest in the prevalence, composition and adaptive benefits of maternal effects, little is still known of their impact on ecological and evolutionary processes in natural populations. We consider here the insights that a quantitative genetic framework provides into the pathways by which maternal effects can influence trait evolution in wild populations. Widespread evidence for a genetic basis of a range of maternal effects traits reinforces the notion that they cannot be treated as purely environmental sources of variation. We also provide an overview of the impact of environmental conditions on the expression and impact of maternal effects, and describe empirical evidence for their impact on evolution at ecological time-scales. 3. We emphasize the need for empirical work to quantify the associations between maternal and offspring phenotype and genotype, and the suite of selection pressures generated by maternal effects, as well as the relationship between maternal effects and environmental variation. Future work should aim to identify the conditions under which maternal effects are likely to play a role in evolution, as well as explicitly test the contribution of maternal effects to evolutionary responses.