Data from: Interplay of robustness and plasticity of life history traits drives ecotypic differentiation in thermally distinct habitats

Phenotypic plasticity describes the ability of an individual to alter its phenotype in response to the environment and is potentially adaptive when dealing with environmental variation. However, robustness in the face of a changing environment may often be beneficial for traits that are tightly linked to fitness. We hypothesized that robustness of some traits may depend on specific patterns of plasticity within and among other traits. We used a reaction norm approach to study robustness and phenotypic plasticity of three life history traits of the collembolan Orchesella cincta in environments with different thermal regimes. We measured adult mass, age at maturity and growth rate of males and females from heath and forest habitats at two temperatures (12 and 22 °C). We found evidence for ecotype-specific robustness of female adult mass to temperature, with a higher level of robustness in the heath ecotype. This robustness is facilitated by plastic adjustments of growth rate and age at maturity. Furthermore, female fecundity is strongly influenced by female adult mass, explaining the importance of realizing a high mass across temperatures for females. These findings indicate that different predicted outcomes of life history theory can be combined within one species’ ontogeny and that models describing life history strategies should not assume that traits like growth rate are maximized under all conditions. On a methodological note, we report a systematic inflation of variation when standard deviations and correlation coefficients are calculated from family means as opposed to individual data within a family structure.

表型可塑性（Phenotypic plasticity）指个体响应环境变化而调整自身表型的能力，在应对环境波动时往往具备适应性价值。然而，与适合度（fitness）紧密关联的性状，其稳健性（robustness）在多变环境中通常也能带来显著益处。我们提出假说：部分性状的稳健性可能依赖于其他性状内部及性状间的特定可塑性模式。本研究采用反应规范（reaction norm）研究方法，针对弹尾纲跳虫（collembolan）带唇棘跳虫（Orchesella cincta）的三种生活史性状，在不同热环境下的稳健性与表型可塑性展开探究。我们在12℃与22℃两个温度条件下，测量了取自灌丛生境与森林生境的雌雄个体的成虫体重、成熟年龄及生长速率。研究发现，雌性成虫体重对温度的稳健性存在生态型特异性：灌丛生境生态型的稳健性水平更高，且该稳健性通过生长速率与成熟年龄的可塑性调节得以实现。此外，雌性繁殖力（fecundity）显著受其成虫体重影响，这解释了雌性在不同温度环境下均需达成较高体重的重要性。本研究结果表明，生活史理论的不同预测结果可在同一物种的个体发育（ontogeny）过程中实现整合，且描述生活史策略的模型不应假设生长速率等性状在所有条件下均处于最大化状态。在方法学层面，我们发现一种系统性偏差：当从家系均值而非家系内的个体数据计算标准差与相关系数时，会出现变异量的系统性膨胀。