Data from: Quantifying individual heterogeneity and its influence on life-history trajectories: Different methods for different questions and contexts

Heterogeneity among individuals influences the life-history trajectories we observe at the population level because viability selection, selective immigration and emigration processes, and ontogeny change the proportion of individuals with specific trait values with increasing age. Here, we review the two main approaches that have been proposed to account for these processes in life-history trajectories, contrasting how they quantify ontogeny and selection, and proposing ways to overcome some of their limitations. Nearly all existing approaches to model individual heterogeneity assume either a single normal distribution or a priori known groups of individuals. Ontogenetic processes, however, can vary across individuals through variation in life-history tactics. We show the usefulness of describing ontogenetic processes by modelling trajectories with a mixture model that focuses on heterogeneity in life-history tactics. Additionally, most methods examine individual heterogeneity in a single trait, ignoring potential correlations among multiple traits caused by latent common sources of individual heterogeneity. We illustrate the value of using a joint modelling approach to assess the presence of a shared latent correlation and its influence on life-history trajectories. We contrast the strengths and limitations of different methods for different research questions, and we exemplify the differences among methods using empirical data from long-term studies of ungulates.个体间的异质性会影响种群水平上观测到的生活史轨迹，究其原因在于存活选择、选择性迁入与迁出过程以及个体发育（ontogeny）会随年龄增长，改变携带特定性状值的个体比例。本文综述了两类用于阐释生活史轨迹中上述过程的主流研究方法，对比二者在量化个体发育与选择作用的方式差异，并提出了克服部分方法局限的可行路径。当前几乎所有用于构建个体异质性模型的方法，均假设个体性状服从单一正态分布，或先验确定个体分组类别。然而基于生活史策略的差异，个体间的发育过程也存在分化。本文证实，通过聚焦生活史策略异质性的混合模型对轨迹进行建模，可有效刻画个体发育过程。此外，多数方法仅针对单一性状开展个体异质性分析，忽略了由个体异质性的潜在共同来源所引发的多性状间潜在关联。本文通过联合建模方法，演示了如何评估潜在共享关联的存在性及其对生活史轨迹的影响，凸显该方法的应用价值。本文针对不同研究问题对比了各类方法的优势与局限，并结合有蹄类动物长期野外研究的实证数据，展示了不同方法间的差异。