title: Fitness consequences of maternal and grandmaternal effects.
abstract: Transgenerational effects are broader than only parental relationships. Despite mounting evidence that multigenerational effects alter phenotypic and life-history traits, our understanding of how they combine to determine fitness is not well developed because of the added complexity necessary to study them. Here, we derive a quantitative genetic model of adaptation to an extraordinary new environment by an additive genetic component, phenotypic plasticity, maternal and grandmaternal effects. We show how, at equilibrium, negative maternal and negative grandmaternal effects maximize expected population mean fitness. We define negative transgenerational effects as those that have a negative effect on trait expression in the subsequent generation, that is, they slow, or potentially reverse, the expected evolutionary dynamic. When maternal effects are positive, negative grandmaternal effects are preferred. As expected under Mendelian inheritance, the grandmaternal effects have a lower impact on fitness than the maternal effects, but this dual inheritance model predicts a more complex relationship between maternal and grandmaternal effects to constrain phenotypic variance and so maximize expected population mean fitness in the offspring.
authors.affiliation: Department of Mathematics, Faculty of Engineering and Physical Sciences, University of Surrey Guildford, Surrey, GU2 7XH, UK ; Department of Electrical Engineering, Indian Institute of Technology Bombay Powai, Mumbai, 400076, India ; Institute of Science and Technology Austria Klosterneuburg, Austria.
authors.forename: Roshan
authors.initials: R
authors.lastname: Prizak
authors.affiliation: Department of Mathematics, Faculty of Engineering and Physical Sciences, University of Surrey Guildford, Surrey, GU2 7XH, UK ; Centre for Biological Sciences, University of Southampton Life Sciences Building 85, Highfield Campus, Southampton, SO17 1BJ, UK.
authors.forename: Thomas H G
authors.initials: TH
authors.lastname: Ezard
authors.affiliation: Department of Mathematics, Faculty of Engineering and Physical Sciences, University of Surrey Guildford, Surrey, GU2 7XH, UK.
authors.forename: Rebecca B
authors.initials: RB
authors.lastname: Hoyle
keywords: Adaptation; indirect genetic effect; maternal effect; phenotypic evolution; phenotypic plasticity; quantitative genetics