Romero-Mujalli Daniel, Fuchs Laura I R, Haase Martin, Hildebrandt Jan-Peter, Weissing Franz J, Revilla Tomás A
Zoological Institute and Museum, University of Greifswald, Greifswald, Germany.
Institute for Botany and Landscape Ecology, University of Greifswald, Greifswald, Germany.
Evol Lett. 2024 Mar 27;8(4):561-574. doi: 10.1093/evlett/qrae012. eCollection 2024 Aug.
Plasticity is found in all domains of life and is particularly relevant when populations experience variable environmental conditions. Traditionally, evolutionary models of plasticity are non-mechanistic: they typically view reactions norms as the target of selection, without considering the underlying genetics explicitly. Consequently, there have been difficulties in understanding the emergence of plasticity, and in explaining its limits and costs. In this paper, we offer a novel mechanistic approximation for the emergence and evolution of plasticity. We simulate random "epigenetic mutations" in the genotype-phenotype mapping, of the kind enabled by DNA-methylations/demethylations. The frequency of epigenetic mutations at loci affecting the phenotype is sensitive to organism stress (trait-environment mismatch), but is also genetically determined and evolvable. Thus, the "random motion" of epigenetic markers enables developmental learning-like behaviors that can improve adaptation within the limits imposed by the genotypes. However, with random motion being "goal-less," this mechanism is also vulnerable to developmental noise leading to maladaptation. Our individual-based simulations show that epigenetic mutations can hide alleles that are temporarily unfavorable, thus enabling cryptic genetic variation. These alleles can be advantageous at later times, under regimes of environmental change, in spite of the accumulation of genetic loads. Simulations also demonstrate that plasticity is favored by natural selection in constant environments, but more under periodic environmental change. Plasticity also evolves under directional environmental change as long as the pace of change is not too fast and costs are low.
可塑性存在于生命的所有领域，当种群经历多变的环境条件时，它尤其重要。传统上，可塑性的进化模型是非机械性的：它们通常将反应规范视为选择的目标，而没有明确考虑潜在的遗传学。因此，在理解可塑性的出现以及解释其局限性和成本方面存在困难。在本文中，我们为可塑性的出现和进化提供了一种新颖的机械近似方法。我们模拟了基因型-表型映射中的随机“表观遗传突变”，这种突变是由DNA甲基化/去甲基化实现的。影响表型的基因座上的表观遗传突变频率对生物体压力（性状-环境不匹配）敏感，但也是由基因决定且可进化的。因此，表观遗传标记的“随机运动”能够实现类似发育学习的行为，从而在基因型所施加的限制范围内改善适应性。然而，由于随机运动是“无目标的”，这种机制也容易受到发育噪声的影响，导致适应不良。我们基于个体的模拟表明，表观遗传突变可以隐藏暂时不利的等位基因，从而产生隐秘的遗传变异。尽管存在遗传负荷的积累，但在环境变化的情况下，这些等位基因在以后可能会变得有利。模拟还表明，在恒定环境中自然选择有利于可塑性，但在周期性环境变化下更有利于可塑性。只要变化速度不太快且成本较低，可塑性在定向环境变化下也会进化。
