A heuristic model on the role of plasticity in adaptive evolution: plasticity increases adaptation, population viability and genetic variation

Abstract

An ongoing new synthesis in evolutionary theory is expanding our view of the sources of heritable variation beyond point mutations of fixed phenotypic effects to include environmentally sensitive changes in gene regulation. This expansion of the paradigm is necessary given ample evidence for a heritable ability to alter gene expression in response to environmental cues. In consequence, single genotypes are often capable of adaptively expressing different phenotypes in different environments, i.e. are adaptively plastic. We present an individual-based heuristic model to compare the adaptive dynamics of populations composed of plastic or non-plastic genotypes under a wide range of scenarios where we modify environmental variation, mutation rate and costs of plasticity. The model shows that adaptive plasticity contributes to the maintenance of genetic variation within populations, reduces bottlenecks when facing rapid environmental changes and confers an overall faster rate of adaptation. In fluctuating environments, plasticity is favoured by selection and maintained in the population. However, if the environment stabilizes and costs of plasticity are high, plasticity is reduced by selection, leading to genetic assimilation, which could result in species diversification. More broadly, our model shows that adaptive plasticity is a common consequence of selection under environmental heterogeneity, and hence a potentially common phenomenon in nature. Thus, taking adaptive plasticity into account substantially extends our view of adaptive evolution.

Physiological mechanisms of adaptive developmental plasticity in Rana temporaria island populations

“…Environmental heterogeneity affects the degree of adaptive developmental plasticity, as predicted by theory [9, 14] and demonstrated empirically [15, 16]. Thus, heterogeneous environments are expected to select for highly plastic genotypes, whereas homogeneous environments would tend to reduce plasticity, especially if there are maintenance costs associated to such plasticity [17–19].…”

Individual differences in the potential and realized developmental plasticity of personality traits

“…For instance, Ydenberg and Prins (2012) defined "flexibility" as the ability to adjust foraging behavior as circumstances change, but then noted that flexible individuals might not actually change their behavior if their original behavior performed well under the new set of conditions. Similarly, a recent theoretical model of the effects of phenotypic plasticity on population dynamics distinguished between the range of phenotypes that an individual is able to generate (plasticity-range), and the extent to which an individual's phenotype actually changes in a given situation (plasticity-used) (Gomez-Mestre and Jovani, 2013).…”

Phenotypic variability can promote the evolution of adaptive plasticity by reducing the stringency of natural selection

“…Models of limitations on the evolution of plasticity vary in both the treatment of populations and in the nature of the links between genotypes, environments and phenotypes. Approaches to modelling the evolving populations include quantitative genetics (Via & Lande, ; De Jong, ; Van Tienderen et al ; Gomulkiewicz & Kirkpatrick, ; Gavrilets & Scheiner, ; Lande, ), adaptive dynamics (Ernande & Dieckmann, ) and population genetics (Draghi & Whitlock, ; Gomez‐Mestre & Jovani, ; Leimar, Hammerstein, & Dooren, ; Scheiner & Holt, ; Svanbäck, Pineda‐Krch, & Doebeli, ). Models also differ in whether the plastic trait arises from the interactions of explicit loci (e.g.…”