Print PageThe ability to respond rapidly to ecological change lets organisms optimize their fitness for as much time as possible. The clear adaptive benefits of this ability has prompted an explosion of interest in evolvability in general, and alternative inheritance mechanisms in particular, including phenotypic plasticity, epigenetic inheritance and maternal/parental effects. Lande and Kirkpatrick used Quantitative Genetic models to show that maternal effects cause transients or momentum in phenotypic change – the maternal effects induce time lags so that the phenotype continues to evolve even when selection is turned off. Recasting the same quantitative genetic models in a control theory setting, we provide `proof of concept’ that the influence of maternal effects is more far reaching. We show that maternal effects can enlarge the range of achievable phenotypes and in some cases can even change its course.
Results/Conclusions
According to the multivariate breeders equation, without maternal effects phenotypes will evolve along paths of least genetic resistance. These paths of evolution are visualized by plotting ellipsoids or clouds in phenotype space. When maternal effects are include, the induced time lags cause these ellipsoids to warp, increasing in volume as the maternal effect is strengthened, suggesting that maternal effects can enhance phenotypic diversity. More fundamentally, we find that the direction of evolution in the presence of maternal effects can (depending on the maternal effects) be orthogonal to the direction of evolution without maternal effects. In this sense, parental responses to ecological change may not only give momentum to evolution but these parental responses can actually alter its course.
