Theoretical Ecology Group, Department of Mathematical Sciences, Stellenbosch University, Matieland 7602, South Africa
Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Matieland 7602, South Africa.
J R Soc Interface. 2018 Nov 14;15(148):20180371. doi: 10.1098/rsif.2018.0371.
Understanding the factors that shape the timing of life-history switch points (SPs; e.g. hatching, metamorphosis and maturation) is a fundamental question in evolutionary ecology. Previous studies examining this question from a fitness optimization perspective have advanced our understanding of why the timing of life-history transitions may vary across populations and environments. However, in nature we also often observe variability among individuals within populations. Optimization theory, which typically predicts a single optimal SP under physiological and environmental constraints for a given environment, cannot explain this variability. Here, we re-examine the evolution of a single life-history SP between juvenile and adult stages from an Adaptive Dynamics (AD) perspective, which explicitly considers the feedback between the dynamics of population and the evolution of life-history strategy. The AD model, although simple in structure, exhibits a diverse range of evolutionary scenarios depending upon demographic and environmental conditions, including the loss of the juvenile stage, a single optimal SP, alternative optimal SPs depending on the initial phenotype, and sympatric coexistence of two SP phenotypes under disruptive selection. Such predictions are consistent with previous optimization approaches in predicting life-history SP variability across environments and between populations, and in addition they also explain within-population variability by sympatric disruptive selection. Thus, our model can be used as a theoretical tool for understanding life-history variability across environments and, especially, within species in the same environment.
理解塑造生活史转换点（例如孵化、变态和成熟）时间的因素是进化生态学中的一个基本问题。以前从适应度优化的角度研究这个问题的研究增进了我们对为什么生活史转变的时间可能在不同的种群和环境中有所不同的理解。然而，在自然界中，我们也经常观察到种群内个体之间的可变性。优化理论通常预测在给定环境下的生理和环境限制下，单个最优 SP，但不能解释这种可变性。在这里，我们从适应动态（AD）的角度重新审视了从青少年到成年阶段的单一生活史 SP 的进化，该理论明确考虑了种群动态和生活史策略进化之间的反馈。尽管 AD 模型结构简单，但根据人口和环境条件，它表现出了多种多样的进化情景，包括失去青少年阶段、单一最优 SP、取决于初始表型的替代最优 SP 以及在破坏性选择下两个 SP 表型的同域共存。这些预测与以前的优化方法一致，即预测不同环境和不同种群之间的生活史 SP 可变性，此外，通过同域破坏性选择，还解释了种群内的可变性。因此，我们的模型可以作为一种理论工具，用于理解跨环境的生活史可变性，尤其是在同一环境中的物种内。
