Ecological Significance of Individual Variation in Physiology

哺乳动物牙齿的牙釉质可以从简单的平行排列的晶石（非棱柱状牙釉质）到复杂的非平行排列的牙釉质（棱柱状牙釉质）之间变化。棱柱状牙釉质增加了牙齿的强度，但我们对非棱柱状牙釉质的功能知之甚少。在人类中，非棱柱状牙釉质比其下的棱柱状牙釉质更能抵抗膳食酸和糖副产品的侵蚀破坏。本研究考察了一系列哺乳动物的牙齿结构、饮食多样性和唾液化学。它将检验一种假设，即非棱柱状牙齿表面的夸张层是一种适应，允许饮食强调酸性或含糖食物来源。对每个物种，测量食物硬度、天然日粮的含糖量和酸度，以及唾液pH值和缓冲能力。用扫描电镜测定了磨牙中非棱柱状牙釉质的比例。据预测，具有高比例非棱柱牙釉质的哺乳动物比具有相对较少非棱柱牙釉质的哺乳动物吃的食物更含糖、更酸、更软。唾液pH值和缓冲能力被预测相对较低的物种显示出大量的非棱柱状牙釉质。这项研究将为牙釉质形态、口腔生理和摄食行为之间的相互作用提供证据，这些相互作用限制了哺乳动物选择食物的多样性。这将使我们更好地理解解剖学、生理学和行为之间的关系，这些关系影响着动物分享食物和植物资源的方式。它将提供对灭绝或鲜为人知的物种的饮食的深入了解。这项研究的结果也可能对人类非棱柱形牙在抵抗牙齿侵蚀和开始蛀牙方面的作用产生见解。

9507488 Dumont The organization of enamel in mammalian teeth can vary between simple parallel arrangement of crystallite (nonprismatic enamel) to complicated non-parallel arrangements (prismatic enamel). Prismatic enamel increases the strength of the tooth, but we know relatively little about the function of non-prismatic enamel. In humans, non- prismatic enamel is more resistant to erosive destruction by dietary acids and sugar by-products than is underlying prismatic enamel. This research examines tooth structure, diet diversity, and salivary chemistry in an array of mammal species. It will test the hypothesis that exaggerated superficial layers of nonprismatic tooth are adaptations that permit dietary emphases on acidic or sugary food sources. For each species, food hardness, sugar content and acidity of natural diets are measured, together with salivary pH and buffering capacity. The proportion of nonprismatic enamel in molar teeth is measured using scanning electron microscopy. Mammals with high proportions of nonprismatic enamel are predicted to consume foods that are more sugary, acidic, and softer than those eaten by species that exhibit relatively little nonprismatic enamel. Salivary pH and buffering capacity are predicted to be relatively lower among species that exhibit large proportions of nonprismatic enamel. This study will provide evidence of the interactions between tooth enamel morphology, oral physiology and feeding behavior that limit the diversity of foods that mammals select. It will lead to better understanding of the relationships between anatomy, physiology and behavior that influence the ways in which animals share food plant resources. It will provide insight into the diets of extinct or poorly known species. The results of this study may also yield insights into the role of human nonprismatic e namel in resisting dental erosion and the initiation of tooth decay.