Context‐Dependent Intergenerational Effects: The Interaction between Past and Present Environments and Its Effect on Population Dynamics

Abstract

Intergenerational effects arise when parents' actions influence the reproduction and survival of their offspring and possibly later descendants. Models suggest that intergenerational effects have important implications for both population dynamical patterns and the evolution of life-history traits. However, these will depend on the nature and duration of intergenerational effects. Here we show that manipulating parental food environments of soil mites produced intergenerational effects that were still detectable in the life histories of descendents three generations later. Intergenerational effects varied in different environments and from one generation to the next. In low-food environments, variation in egg size altered a trade-off between age and size at maturity and had little effect on the size of eggs produced in subsequent generations. Consequently, intergenerational effects decreased over time. In contrast, in high-food environments, variation in egg size predominantly influenced a trade-off between fecundity and adult survival and generated increasing variation in egg size. As a result, the persistence and significance of intergenerational effects varied between high- and low-food environments. Context-dependent intergenerational effects can therefore have complex but important effects on population dynamics.

The influence of context-dependent maternal effects on population dynamics: an experimental test

“…Consequently, we hypothesized that maternal effects would be more likely to persist, and have a bigger influence on population dynamics, in highfood environments compared to low-food environments (Plaistow et al 2006). In this study, we tested this hypothesis.…”

“…However, as the interest in maternal effects as adaptations has grown, and researchers have studied them in more detail (Mousseau & Fox 1998a;Marshall & Uller 2007;Räsänen & Kruuk 2007), our understanding of the nature of maternal effects has changed. For example, we now know that maternal effects sometimes have a negative effect on the fitness of offspring (Bernardo 1996b;Einum & Fleming 2000;Mayhew 2001;Plaistow et al 2006;Marshall & Uller 2007); that maternal effects may often last for longer than a single generation and interact in complex ways (Bernardo 1996a;Fox & Savalli 1998;Hercus & Hoffman 2000;Magiafoglou & Hoffmann 2003); and that the expression of maternal effects may be contextdependent, influencing different traits and creating different patterns of trait (co)variation in different environments (Berven 1990;Gliwicz & Guisande 1992;Parichy & Kaplan 1992;Bernardo 1996b;Rossiter 1998;Czesak & Fox 2003;Lardies et al 2004;Marshall & Keough 2004;Räsänen et al 2005;Plaistow et al 2006;Marshall & Uller 2007), or even disappearing in some environments ( Weiner et al 1997;Rossiter 1998;Ergon et al 2001a). Maternal effects may also be dynamic in some instances, with mothers changing how they provision their offspring over time or in different environments (Marshall & Keough 2006;Plaistow et al 2007), and may result from the combined effect of selection on maternal or offspring strategies (Uller 2008).…”

“…Thus, complex maternal effects will lead to complex patterns in the dynamics, feeding, in turn, into complex patterns of phenotypic dynamics. Consequently, there is a real need to characterize and quantify context-dependent maternal effects over time in different systems (Plaistow et al 2006;Marshall & Uller 2007). Such investigations really need to be experimental (Rossiter 1994), because statistical modelling of censused populations in the field will rarely (if ever) have the power to separate maternal effects from changes in other extrinsic and intrinsic aspects of the immediate neonate environment (Albon et al 1987;Lindström 1999).…”

“…A fully factorial, multi-environment study showed that when multiple traits were measured, an environmental perturbation that generated maternal effects (i.e. caused females to lay different types of eggs) was still detectable in the life histories of descendents three generations later (Plaistow et al 2006). In high-food environments, the maternal effect primarily influenced a tradeoff between fecundity and survival and resulted in increasing differences in the average size of eggs that females in different treatment groups laid over the course of the experiment.…”

Why does offspring size affect performance? Integrating metabolic scaling with life-history theory

“…For example, in some instances, increased offspring size can confer a fitness disadvantage, where bigger offspring have higher mortality than smaller offspring [9]. Generally, offspring size effects manifest in early development, but they can persist throughout the life history affecting reproduction and even the performance of the subsequent generation [10]. Understanding the relationship between offspring size and performance is of fundamental importance to life-history theorists because this relationship should drive the evolution of offspring size and explain the massive variation in offspring size we observe among species [11].…”