Genetics and the evolution of primate enamel thickness: A baboon model
Genetics and the evolution of primate enamel thickness: A baboon model
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DOI：
10.1002/ajpa.10353
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发表时间：
2004-07-01
影响因子：
2.8
通讯作者：
Mahaney, MC
中科院分区：
文献类型：
--
作者：
Hlusko, LJ;Suwa, G;Mahaney, MC
哺乳动物牙釉质的厚度在古生物学中起着重要作用，因为它与饮食相关，而较厚的牙釉质可以防止牙齿断裂和磨损。 30多年来，从将“腊玛古猿”鉴定为早期中新世原始人类，到最近发现最早的原始人类的臼齿釉质厚度介于现存黑猩猩和南方古猿之间，原始人类进化研究一直强调这一特征的重要性。尽管现代物种之间存在显着差异，但非人科灵长类化石的牙釉质厚度在很大程度上仍未被探索。尽管牙釉质厚度变化对灵长类动物的进化很重要，但这种性状变化的机制尚未阐明。我们在这里报告了对灵长类动物牙釉质厚度的首次定量遗传分析，该分析基于来自圈养繁殖群的 506 只纯种狒狒。对 44 颗狒狒下颌磨牙的计算机断层扫描分析显示，原圆锥侧面有一个牙釉质厚度足够均匀的区域。有了这些知识，我们开发了一种卡尺测量协议，用于在该区域内磨损的狒狒磨牙，从而能够收集足够大的数据集以进行遗传分析。定量遗传分析表明，牙釉质厚度的表型变异很大一部分是由于基因的累加效应造成的，并且与性别和牙齿大小无关。我们的模型预测，牙釉质厚度可以快速跟踪地质时期的饮食适应性变化，从而增加该特征同质性的可能性。这些结果对分析人科动物牙釉质厚度变化具有重要意义，并为探索帕帕宁化石记录中这种表型的演化提供了基础。 (C) 2004 Wiley-Liss, Inc.
The thickness of mammalian tooth enamel plays a prominent role in paleontology because it correlates with diet, and thicker enamel protects against tooth breakage and wear. Hominid evolutionary studies have stressed the importance of this character for over 30 years, from the identification of "Ramapithecus" as an early Miocene hominid, to the recent discovery that the earliest hominids display molar enamel intermediate in thickness between extant chimpanzees and Australopithecus. Enamel thickness remains largely unexplored for nonhominoid primate fossils, though there is significant variation across modern species. Despite the importance of enamel thickness variation to primate evolution, the mechanisms underlying variation in this trait have not yet been elucidated. We report here on the first quantitative genetic analysis of primate enamel thickness, an analysis based on 506 pedigreed baboons from a captive breeding colony. Computed tomography analysis of 44 Papio mandibular molars shows a zone of sufficiently uniform enamel thickness on the lateral surface of the protoconid. With this knowledge, we developed a caliper metric measurement protocol for use on baboon molars worn to within this zone, enabling the collection of a data set large enough for genetic analyses. Quantitative genetic analyses show that a significant portion of the phenotypic variance in enamel thickness is due to the additive effects of genes and is independent of sex and tooth size. Our models predict that enamel thickness could rapidly track dietary adaptive shifts through geological time, thus increasing the potential for homoplasy in this character. These results have implications for analyses of hominoid enamel thickness variation, and provide a foundation from which to explore the evolution of this phenotype in the papionin fossil record. (C) 2004 Wiley-Liss, Inc.