Mechanisms by Which Phenotypic Plasticity Affects Adaptive Divergence and Ecological Speciation

Abstract

Phenotypic plasticity is the ability of one genotype to produce different phenotypes depending on environmental conditions. Several conceptual models emphasize the role of plasticity in promoting reproductive isolation and, ultimately, speciation in populations that forage on two or more resources. These models predict that plasticity plays a critical role in the early stages of speciation, prior to genetic divergence, by facilitating fast phenotypic divergence. The ability to plastically express alternative phenotypes may, however, interfere with the early phase of the formation of reproductive barriers, especially in the absence of geographic barriers. Here, we quantitatively investigate mechanisms under which plasticity can influence progress toward adaptive genetic diversification and ecological speciation. We use a stochastic, individual-based model of a predator-prey system incorporating sexual reproduction and mate choice in the predator. Our results show that evolving plasticity promotes the evolution of reproductive isolation under diversifying environments when individuals are able to correctly select a more profitable habitat with respect to their phenotypes (i.e., adaptive habitat choice) and to assortatively mate with relatively similar phenotypes. On the other hand, plasticity facilitates the evolution of plastic generalists when individuals have a limited capacity for adaptive habitat choice. We conclude that plasticity can accelerate the evolution of a reproductive barrier toward adaptive diversification and ecological speciation through enhanced phenotypic differentiation between diverging phenotypes.

The evolution of intraspecific variation in social organization

“…Variation in ecological conditions between populations could lead to genetic differentiation affecting the social system and thus IVSO between populations. This could be the starting point of speciation (Meynard, Pillay, Perrigault, Caminade, & Ganem, ; Nonaka, Svanbäck, Thibert‐Plante, Englund, & Brännström, ; Rymer, Pillay, & Schradin, ).…”

Behavioral adaptations imply a direct link between ecological specialization and reproductive isolation in a sympatrically diverging ground beetle

“…; Thibert‐Plante and Gavrilets ; Nonaka et al. ). Indeed, models on the role of plasticity in promoting ecological divergence suggest that the evolution of a reproductive barrier can be strongly facilitated by phenotypic plasticity if dispersal events take place after the development of the plastic phenotype (Thibert‐Plante and Gavrilets ) and an individual's settlement in a particular habitat depends on its phenotype (i.e., adaptive habitat choice; Nonaka et al.…”

Phenotypic plasticity of mate recognition systems prevents sexual interference between two sympatric leaf beetle species

“…The evolutionary consequences of phenotype‐mediated assortative mating may be the same as in habitat‐assortative mating if the expressed phenotype is linked to the habitat (West‐Eberhard 2003; Nonaka et al. ). Thus, assortative mating due to host plant dependent insect phenotypes can be considered as an extension of host‐associated mating in phytophagous insects (Diehl and Bush ), as matings are indirectly host‐mediated, but not spatially restricted to the host species.…”

“…2010; Thibert‐Plante and Hendry ; Wund 2012; Thibert‐Plante and Gavrilets ; Nonaka et al. ). Our results bridge between community ecology and evolutionary biology by illustrating the potential role of phenotypic plasticity for phytophagous insect communities and ecological speciation.…”