Team Evo-Devo of Vertebrate Dentition, Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, CNRS UMR 5242, UCBL 1, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, Lyon Cedex 07, France.
Evolution. 2013 Jun;67(6):1792-804. doi: 10.1111/evo.12051. Epub 2013 Feb 12.
The extant mammals have evolved highly diversified diets associated with many specialized morphologies. Two rare diets, termitophagy and vermivory, are characterized by unusual morphological and dental adaptations that have evolved independently in several clades. Termitophagy is known to be associated with increases in tooth number, crown simplification, enamel loss, and the appearance of intermolar diastemata. We observed similar modifications at the species level in vermivorous clades, although interestingly the vermivorous mammals lack secondarily derived tools that compensate for the dentition's reduced function. We argue that the parallel dental changes in these specialists are the result of relaxed selection on occlusal functions of the dentition, which allow a parallel cascade of changes to occur independently in each clade. Comparison of the phenotypes of Rhynchomys, a vermivorous rat, and strains of mice whose ectodysplasin (EDA) pathway has been mutated revealed several shared dental features. Our results point to the likely involvement of this genetic pathway in the rapid, parallel morphological specializations in termitophagous and vermivorous species. We show that diets or feeding mechanisms in other mammals that are linked to decreased reliance on complex can lead to similar cascades of change.
现存的哺乳动物已经进化出高度多样化的饮食，与许多专门的形态相关。两种罕见的饮食，食蚁兽和食虫，其特点是具有不寻常的形态和牙齿适应性，这些适应性在几个分支中独立进化而来。食蚁兽与牙齿数量的增加、冠部简化、釉质丧失以及磨牙之间出现间隙有关。我们在食虫的分支中观察到了类似的在物种水平上的变化，尽管有趣的是，食虫哺乳动物缺乏补偿牙齿功能降低的次生工具。我们认为，这些专家的平行牙齿变化是牙齿咬合功能选择放松的结果，这使得平行的变化级联可以在每个分支中独立发生。对食虫的沙鼠和其外胚层发育不良（EDA）途径发生突变的几种小鼠品系的表型进行比较，揭示了几个共同的牙齿特征。我们的研究结果表明，该遗传途径可能参与了食蚁兽和食虫物种的快速、平行的形态特化。我们表明，其他与降低对复杂的咀嚼依赖有关的哺乳动物的饮食或进食机制可能导致类似的变化级联。
