Data from: How to measure maturation: a comparison of probabilistic methods used to test for genotypic variation and plasticity in the decision to mature

Maturation is a developmental trait that plays a key role in shaping organisms’ life-history. However, progress in understanding how maturation phenotypes evolve has been held back by confusion over how best to model maturation decisions and a lack of studies comparing genotypic variation in maturation. Here, we fitted probabilistic maturation reaction norms (PMRNs) to data collected from five clones of Daphnia magna and five of Daphnia pulex collected from within and between different populations. We directly compared the utility of modeling approaches that assume maturation to be a process with an instantaneous rate with those that do not by fitting maturation rate and logistic regression models, and emphasize similarities and differences between them. Our results demonstrate that in Daphnia, PMRNs using a logistic regression approach were simpler to use and provided a better fit to the data. The decision to mature was plastic across a range of growth trajectories and dependent upon both body size and age. However, the age effect was stronger in D. magna than D. pulex and varied considerably between clones. Our results support the idea that maturation thresholds can evolve but also suggest that the notion of a threshold based on a single fixed state is an oversimplification that underestimates the adaptability of these important traits.

成熟是一种发育性状，在塑造生物体生活史的过程中发挥关键作用。然而，由于如何最优建模成熟决策的认知困惑，以及缺乏针对成熟过程中基因型变异的比较研究，学界对成熟表型演化的理解进展一直受阻。本研究基于从不同种群内部及种群间采集的5个大型溞（Daphnia magna）克隆株与5个蚤状溞（Daphnia pulex）克隆株的实验数据，拟合了概率性成熟反应范数（probabilistic maturation reaction norms, PMRNs）。我们通过拟合成熟速率模型与逻辑回归模型，直接对比了将成熟视为瞬时速率过程的建模方法与非此类方法的应用效果，并阐明了二者的异同。研究结果表明，在水蚤属物种中，采用逻辑回归方法构建的PMRNs操作更为简便，且对数据的拟合效果更优。成熟决策在一系列生长轨迹中具有表型可塑性，且同时受个体体型与年龄的影响。不过，大型溞中年龄的影响效应强于蚤状溞，且不同克隆株间的差异显著。本研究结果支持成熟阈值可发生演化这一观点，但同时也表明，基于单一固定状态的阈值概念过于简化，低估了这类重要性状的适应性潜力。