Abstract
It has been argued that adaptive phenotypic plasticity may facilitate range expansions over spatially and temporally variable environments. However, plasticity may induce fitness costs. This may hinder the evolution of plasticity. Earlier modelling studies examined the role of plasticity during range expansions of populations with fixed genetic variance. However, genetic variance evolves in natural populations. This may critically alter model outcomes. We ask: how does the capacity for plasticity in populations with evolving genetic variance alter range margins that populations without the capacity for plasticity are expected to attain? We answered this question using computer simulations and analytical approximations. We found a critical plasticity cost above which the capacity for plasticity has no impact on the expected range of the population. Below the critical cost, by contrast, plasticity facilitates range expansion, extending the range in comparison to that expected for populations without plasticity. We further found that populations may evolve plasticity to buffer temporal environmental fluctuations, but only when the plasticity cost is below the critical cost. Thus, the cost of plasticity is a key factor involved in range expansions of populations with the potential to express plastic response in the adaptive trait.This article is part of the theme issue ‘Species' ranges in the face of changing environments (part I)’.
Highlights
Owing to ongoing climate change and increasing human impact on ecosystems, many populations need to adapt to novel conditions either in their present geographical distributions, or in new areas they face while altering their ranges [1,2,3,4,5]
After the burn-in period, we found that when the cost of plasticity was higher than the critical cost δc, plasticity was very low (
Theoretical understanding of the role of plasticity in the establishment of range margins was limited to situations in which genetic variance is an fixed, rather than an evolving, property of a population [9]
Summary
Owing to ongoing climate change and increasing human impact on ecosystems, many populations need to adapt to novel conditions either in their present geographical distributions, or in new areas they face while altering their ranges [1,2,3,4,5]. The above theoretical prediction is critically altered when genetic variance is allowed to evolve Under this assumption, populations expanding their ranges over an environment that changes linearly in space (with a constant carrying capacity) will either adapt to the entire available habitat or face global extinction [10]. For range expansions over environments that change linearly in space (with genetic variance allowed to evolve), drift may cause non-trivial range margins to be established when the local carrying capacity decreases away from the core habitat [11]. We address this issue by modelling a population, with evolving genetic variance, expanding its range over a steepening environmental gradient This is a situation in which a population without plasticity is expected to attain a non-trivial range margin, even when the carrying capacity is not constrained to be decreasing away from the core habitat [11].
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