The question of how complex morphologies evolve, given constraints imposed by genetic, developmental and functional factors, has been a topic of inquiry for many decades. In the mid-twentieth century the study of morphological trait covariation, and the implications of this for evolutionary diversification, was developed under the general concept of "morphological integration". Given the polygenic inheritance model underlying quantitative skeletal traits, and the existence of differential pleiotropic effects, it is assumed that variation in the genotype to phenotype map will lead to the emergence of semi-autonomous "modules" that share relatively stronger covariance (integration) among traits within them. Understanding these potential patterns of modularity in the primate skeleton is important for clarifying the seeming inconsistencies presented by "mosaic" morphologies found in fossil taxa, as well as providing hypothetical units of morphological evolution that can be compared across the primate order. A review of the primate skeletal integration and modularity literature was conducted with the aim of assessing (i) the general nature of primate skeletal integration patterns, and (ii) the extent to which any identified modularity patterns are ubiquitous across primates. The vast literature on cranial integration reveals some consistency in suggesting that the face and the neurocranium (and in some cases, the basicranium and vault) form distinct modules, but the intensity of this modular pattern varies across taxa. The much more modest postcranial integration literature suggests that apes show overall reduced covariation among skeletal regions compared with other anthropoid taxa, but the extent to which any identified modularity patterns hold true across primates is still very unclear. While much has been learned about primate skeletal integration in the past two decades, we still need more studies that establish benchmarks as to what constitutes an integrated modular structure, and that empirically test these potential modules across a wider range of primate taxa.

中文翻译：

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灵长类骨骼中的整合和模块化模式：综述。

几十年来，在遗传、发育和功能因素施加的限制下，复杂形态如何演变的问题一直是研究的主题。在二十世纪中叶，形态特征协变的研究及其对进化多样化的影响是在“形态整合”的一般概念下发展起来的。鉴于定量骨骼特征的多基因遗传模型，以及差异多效效应的存在，假设基因型到表型图的变化将导致半自主“模块”的出现，这些模块之间共享相对较强的协方差（整合）他们身上的特质。了解灵长类骨骼中这些潜在的模块化模式对于澄清化石类群中发现的“马赛克”形态所呈现的看似不一致以及提供可在整个灵长类目中进行比较的形态进化的假设单位非常重要。对灵长类动物骨骼整合和模块化文献进行了审查，目的是评估 (i) 灵长类动物骨骼整合模式的一般性质，以及 (ii) 任何已识别的模块化模式在灵长类动物中普遍存在的程度。大量关于颅骨整合的文献揭示了一些一致性，表明面部和神经颅骨（在某些情况下，基础颅骨和拱顶）形成不同的模块，但这种模块模式的强度在不同的分类群中有所不同。更为温和的颅后整合文献表明，与其他类人猿类群相比，类人猿在骨骼区域之间的协变总体上有所减少，但任何已识别的模块化模式在灵长类动物中的适用程度仍非常不清楚。虽然在过去的二十年里对灵长类动物的骨骼整合有了很多了解，但我们仍然需要更多的研究来建立关于什么是整合的模块化结构的基准，并在更广泛的灵长类动物分类群中对这些潜在的模块进行实证测试。