Bat Dentitions: A Model System for Studies at the Interface of Development, Biomechanics, and Evolution
Bat Dentitions: A Model System for Studies at the Interface of Development, Biomechanics, and Evolution
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蝙蝠牙列：发育、生物力学和进化界面研究的模型系统
DOI：
10.1093/icb/icac042
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发表时间：
2022
影响因子：
2.6
通讯作者：
Sears, Karen E.
中科院分区：
文献类型：
--
作者：
Santana, Sharlene E.;Grossnickle, David M.;Sadier, Alexa;Patterson, Edward;Sears, Karen E.
哺乳动物复杂牙列的进化是一项重大创新，促进了向新的饮食生态位的扩展，这迫使人们对紧密的形式-功能关系进行选择。牙齿允许哺乳动物通过施加由下颌内收肌、头盖骨和下颌骨组成的第三级杠杆系统产生的力来摄取和加工食物。物理规律决定了下颌不同咬合点位置的咬合力的变化，因此，个别牙齿在进食过程中会经历不同的机械状态。如果哺乳动物的牙列表现出对下颌骨喂养生物力学的功能性适应，那么牙齿有望进化成具有机械优势的大小、形状和位置。在这里，我们将蝙蝠作为一个模型系统来检验这一假说，更广泛地说，用于哺乳动物牙齿多样性的综合研究。我们将现场收集的沿牙齿排的咬合力数据集与30种蝙蝠的牙齿和下颌形态数据结合在一起。我们(1)首次描述了蝙蝠沿牙齿排的咬合力趋势；(2)使用系统发育比较方法来研究咬合力模式、牙齿和下颌形态之间的关系；以及(3)假设这些咬合力模式可能与控制牙齿形成的发育过程有关。我们发现咬合力沿牙列的变化与杠杆力学模型的预测是一致的，大多数物种在第一个下磨牙具有最大的咬合力。下颌体的横截面形状与牙列上最大咬合力的位置密切相关，这可能反映了下颌对不同物种之间不同应力模式的适应。此外，牙齿的饮食适应似乎与沿磨牙形牙齿的咬合力变化有关，食虫物种表现出更大的咬合力，更靠前，更窄的牙齿和下颌，而食果/杂食动物表现出更大的咬合力，更靠后，更宽的牙齿和下颌。由于这些头骨特征是通过发育联系在一起的，饮食专业化似乎形成了控制与摄食性能相关的特征的内在机制。
The evolution of complex dentitions in mammals was a major innovation that facilitated the expansion into new dietary niches, which imposed selection for tight form–function relationships. Teeth allow mammals to ingest and process food items by applying forces produced by a third-class lever system composed by the jaw adductors, the cranium, and the mandible. Physical laws determine changes in jaw adductor (biting) forces at different bite point locations along the mandible (outlever), thus, individual teeth are expected to experience different mechanical regimes during feeding. If the mammal dentition exhibits functional adaptations to mandible feeding biomechanics, then teeth are expected to have evolved to develop mechanically advantageous sizes, shapes, and positions. Here, we present bats as a model system to test this hypothesis and, more generally, for integrative studies of mammal dental diversity. We combine a field-collected dataset of bite forces along the tooth row with data on dental and mandible morphology across 30 bat species. We (1) describe, for the first time, bite force trends along the tooth row of bats; (2) use phylogenetic comparative methods to investigate relationships among bite force patterns, tooth, and mandible morphology; and (3) hypothesize how these biting mechanics patterns may relate to the developmental processes controlling tooth formation. We find that bite force variation along the tooth row is consistent with predictions from lever mechanics models, with most species having the greatest bite force at the first lower molar. The cross-sectional shape of the mandible body is strongly associated with the position of maximum bite force along the tooth row, likely reflecting mandibular adaptations to varying stress patterns among species. Further, dental dietary adaptations seem to be related to bite force variation along molariform teeth, with insectivorous species exhibiting greater bite force more anteriorly, narrower teeth and mandibles, and frugivores/omnivores showing greater bite force more posteriorly, wider teeth and mandibles. As these craniodental traits are linked through development, dietary specialization appears to have shaped intrinsic mechanisms controlling traits relevant to feeding performance.