Data from: Size variation, growth strategies and the evolution of modularity in the mammalian skull

Allometry is a major determinant of within-population patterns of association among traits and, therefore, a major component of morphological integration studies. Even so, the influence of size variation over evolutionary change has been largely unappreciated. Here, we explore the interplay between allometric size variation, modularity, and life history strategies in the skull from representatives of 35 mammalian families. We start by removing size variation from within-species data and analyzing its influence on integration magnitudes, modularity patterns and responses to selection. We also carry out a simulation in which we artificially alter the influence of size variation in within-taxa matrices. Finally, we establish the relationship between size variation and different growth strategies. We demonstrate that a large portion of the evolution of modularity in the mammalian skull is associated to the evolution of growth strategies. Lineages with highly altricial neonates have adult variation patterns dominated by size variation, leading to high correlations among traits regardless of any underlying modular process and impacting directly their potential to respond to selection. Greater influence of size variation is associated to larger inter-module correlations, less individualized modules, and less flexible responses to natural selection.异速生长（Allometry）是种群内性状间关联模式的核心决定因素，因此也是形态整合（morphological integration）研究的核心组成部分。即便如此，体型变异对演化变化的影响在很大程度上仍未得到足够重视。本研究以35个哺乳动物科的代表类群的头骨为研究对象，探讨异速生长体型变异、模块化（modularity）与生活史策略之间的相互作用关系。我们首先从物种内数据中剔除体型变异，分析其对整合强度、模块化模式以及选择响应的影响。此外，我们还开展了一项模拟实验，人为改变类群内矩阵中体型变异的影响权重。最后，我们明确了体型变异与不同生长策略之间的关联。本研究证实，哺乳动物头骨模块化演化的很大一部分与生长策略的演化密切相关。幼崽为高度晚成型的支系，其成体变异模式以体型变异为主导，无论潜在的模块化过程如何，都会导致性状间产生高度关联，并直接影响其对选择的响应潜力。体型变异的影响越强，模块间的关联程度越高，模块的个体化程度越低，对自然选择的响应灵活性也越弱。