Variation in Molar Size and Proportions in the Hominid Lineage: An Inter- and Intraspecific Approach.

IF 2.2 4区 生物学 Q2 BIOLOGY
Integrative Organismal Biology Pub Date : 2024-11-22 eCollection Date: 2024-01-01 DOI:10.1093/iob/obae041
L A D'Addona, V Bernal, P N Gonzalez
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Abstract

The implications of the inhibitory cascade (IC) model in dental diversification have been primarily studied at an interspecific or higher level. In contrast, the study of organisms with recent evolutionary divergence or at an interpopulational scale is still very limited. Here, we assess the effect of changes in molar size and the ratio of local activators to inhibitors on molar proportions based on a compilation of data of crown diameters of the first, second, and third lower and upper molars of extinct and extant hominids and modern human populations. The analysis of allometric changes between the size of each tooth and the size of the molar row shows a negative allometry in first molars (M1), isometric changes in second molars (M2), and a positive allometry in third molars (M3) in both hominin phylogeny and modern human populations. On the other hand, the proportions of lower and upper molars of several hominid species fall outside the morphospace defined by the IC model, while most of the modern human populations fall within the morphospace defined by the model as M1 > M2 > M3. We conclude that there is a phylogenetic structuring for molar size, particularly in the maxilla, with a trend toward mesial-to-distal reduction in the molar row area accompanied by allometric changes. Our findings also show the limitations of the IC model for explaining molar proportions in primates, particularly the variation in the relative size at the interspecific scale in the hominid lineage.

原始人谱系中臼齿大小和比例的变化:种间和种内研究。
抑制级联(IC)模型在牙齿分化中的意义主要是在种间或更高的水平上研究的。相比之下,对具有最近进化分歧或在种群间尺度上的生物的研究仍然非常有限。在这里,我们评估了臼齿大小的变化和局部活化剂与抑制剂的比例对臼齿比例的影响,这是基于对已灭绝和现存的原始人和现代人的第一、第二和第三下颌和上臼齿冠直径的数据汇编。在古人类和现代人群中,每颗牙齿的大小与臼齿排大小之间的异速变化分析显示,第一磨牙(M1)为负异速变化,第二磨牙(M2)为等速变化,第三磨牙(M3)为正异速变化。另一方面,一些古人类物种的上下磨牙比例不在IC模型定义的形态空间范围内,而大多数现代人类种群则在M1 > M2 > M3模型定义的形态空间范围内。我们得出结论,磨牙的大小有一个系统发育结构,特别是在上颌骨,磨牙排面积有中向远端缩小的趋势,并伴有异速变化。我们的研究结果也显示了IC模型在解释灵长类动物臼齿比例方面的局限性,特别是在原始人谱系的种间尺度上的相对大小变化。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
3.70
自引率
6.70%
发文量
48
审稿时长
20 weeks
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