The consequences of phenotypic plasticity for ecological speciation

Abstract

We use an individual‐based numerical simulation to study the effects of phenotypic plasticity on ecological speciation. We find that adaptive plasticity evolves readily in the presence of dispersal between populations from different ecological environments. This plasticity promotes the colonization of new environments but reduces genetic divergence between them. We also find that the evolution of plasticity can either enhance or degrade the potential for divergent selection to form reproductive barriers. Of particular importance here is the timing of plasticity in relation to the timing of dispersal. If plasticity is expressed after dispersal, reproductive barriers are generally weaker because plasticity allows migrants to be better suited for their new environment. If plasticity is expressed before dispersal, reproductive barriers are either unaffected or enhanced. Among the potential reproductive barriers we considered, natural selection against migrants was the most important, primarily because it was the earliest‐acting barrier. Accordingly, plasticity had a much greater effect on natural selection against migrants than on sexual selection against migrants or on natural and sexual selection against hybrids. In general, phenotypic plasticity can strongly alter the process of ecological speciation and should be considered when studying the evolution of reproductive barriers.

Adaptive phenotypic plasticity contributes to divergence between lake and river populations of an East African cichlid fish

“…In particular, adaptive phenotypic plasticity—the generation of a phenotype that is better suited for a novel environment (Ghalambor, McKay, Carroll, & Reznick, 2007)—can promote the expansion of populations into new niches (Yeh & Price, 2004; Richards, Bossdorf, Muth, Gurevitch, & Pigliucci, 2006; Thibert‐Plante & Hendry, 2011). This is because adaptive phenotypic plasticity can temporarily protect genetic diversity from the direct impact of natural selection, thereby saving time for beneficial mutations to arise and to spread within a population, which may eventually result in genetic differentiation (Schlichting, 2004).…”

Long‐term acclimation to reciprocal light conditions suggests depth‐related selection in the marine foundation speciesPosidonia oceanica

“…Differential response of distinct populations to local environmental features either can fall within the phenotypic plasticity range of the species (Hall et al., 2007; Pfennig et al., 2010; Schlichting, 1986; Thibert‐Plante & Hendry, 2011) or can be due to evolutionary changes with underlying genetic differentiation among populations (Dowdall et al., 2012; Sanford & Kelly, 2011; Savolainen, Lascoux, & Merilä, 2013). When changes in environmental conditions occur, species can shift their distributional range (i.e., Parmesan & Yohe, 2003; Perry, Low, Ellis, & Reynolds, 2005) in order to migrate in more suitable habitats.…”

Asymmetric isolating barriers between different microclimatic environments caused by low immigrant survival

“…Because the aim of our study was to mimic natural gene flow and possible barriers to migrants in natural field environments, our use of wild-caught individuals means there are some limitations to the level of inference that can be made, particularly in our ability to uncover the relative role of plasticity versus genetic differences. However, because our finding of higher isolation barriers against immigrants at inland sites seems to be primarily driven by natural selection, how plasticity contributes to isolation between environments will depend on whether it is expressed before or after dispersal occurs [45]. Such limitations are common in field studies involving reciprocal transplant experiments in the wild, but are important for capturing the underlying environmental variation responsible for the different selection pressures that probably lead to local adaptation [25].…”