Data from: The combined effects of temporal autocorrelation and costs of plasticity on the evolution of plasticity

Adaptive phenotypic plasticity is an important source of intraspecific variation, and for many plastic traits the costs or factors limiting plasticity seem cryptic. However, there are several different factors that may constrain the evolution of plasticity, but few models have considered costs and limiting factors simultaneously. Here we use a simulation model to investigate how the optimal level of plasticity in a population depends on a fixed fitness cost for maintaining a potential for plasticity or an incremental fitness cost for producing a plastic response in combination with environmental unpredictability (environmental fluctuation speed) limiting plasticity. Our model identifies two mechanisms that act, almost separately, to constrain the evolution of plasticity: 1) The fitness cost of plasticity scaled by the non-plastic environmental tolerance, and 2) the environmental fluctuation speed scaled by the rate of phenotypic change. That is, the evolution of plasticity is constrained by the high cost of plasticity in combination with high tolerance for environmental variation, or fast environmental changes in combination with slow plastic response. Qualitatively similar results are found when fixed and incremental fitness costs of plasticity are incorporated, although a larger degree of plasticity is selected for with an incremental cost. Our model highlights that it is important to consider direct fitness costs and phenotypic limitations in relation to non-plastic environmental tolerance and environmental fluctuations, respectively, to understand what constrains the evolution of phenotypic plasticity.

适应性表型可塑性（Adaptive phenotypic plasticity）是种内变异（intraspecific variation）的重要来源。对于多数可塑性性状而言，制约其可塑性的成本或影响因素往往较为隐蔽。尽管存在多种可能约束可塑性演化的因素，但目前鲜有模型能够同时兼顾可塑性成本与限制因子。本研究采用模拟模型，探究种群的最优可塑性水平如何依赖于两类因素的组合：一是维持可塑性潜能所需的固定适合度成本（fixed fitness cost），或是产生可塑性响应所需的增量适合度成本（incremental fitness cost）；二是限制可塑性的环境不可预测性（environmental unpredictability，即环境波动速率）。本模型识别出两种几乎独立发挥作用的可塑性演化约束机制：其一为基于非可塑性环境耐受度（non-plastic environmental tolerance）校准的可塑性适合度成本；其二为基于表型变化速率（rate of phenotypic change）校准的环境波动速率。换言之，当可塑性成本偏高且对环境变异的耐受度较高时，或是环境变化较快且表型响应较为迟缓时，可塑性的演化会受到约束。当同时纳入固定与增量适合度成本时，研究得到了定性一致的结果，尽管在增量成本情境下，种群会被选择保留更高程度的可塑性。本研究强调，若要厘清制约表型可塑性演化的核心因素，需分别结合非可塑性环境耐受度与环境波动，考量直接适合度成本与表型限制条件。