Streelman J T, Webb J F, Albertson R C, Kocher T D
Hubbard Center for Genome Studies, 4th Floor, Environmental Technology Building, University of New Hampshire, 35 Colovos Road, Durham, NH 03824, USA.
Evol Dev. 2003 Nov-Dec;5(6):600-8. doi: 10.1046/j.1525-142x.2003.03065.x.
Tooth shape is a hallmark of repeated evolutionary radiations among cichlid fishes from East Africa. Cusp shape and number vary both within populations and among closely related species with different feeding behaviors and ecologies. Here, we use histology and scanning electron microscopy to chart the developmental trajectory of tooth shape differences in fishes from Lake Malawi. We demonstrate that species with bi- or tricuspid adult (replacement) teeth initially possess a first-generation unicuspid dentition. Notably, the timing of turnover from first-generation to replacement teeth differs among species and is correlated with feeding ecology. Next, we use field data for cichlid species with adult unicuspid, bicuspid, and tricuspid teeth to demonstrate a strong and positive relationship between the number of teeth in a row and tooth shape. We discuss cichlid tooth ontogeny in the context of morphogenetic models designed to explain the developmental basis of tooth shape variation in mammals. We suggest that the dramatic differences in cichlid dentitions can be explained by variation in the expression of common activators and inhibitors acting at multiple stages of odontogenesis.
牙齿形状是东非丽鱼科鱼类反复进化辐射的一个标志。在具有不同摄食行为和生态的种群内部以及亲缘关系密切的物种之间，牙尖形状和数量都有所不同。在这里，我们使用组织学和扫描电子显微镜来描绘马拉维湖鱼类牙齿形状差异的发育轨迹。我们证明，具有双尖或三尖成年（替换）牙齿的物种最初拥有第一代单尖牙列。值得注意的是，从第一代牙齿到替换牙齿的更替时间在不同物种之间存在差异，并且与摄食生态相关。接下来，我们使用具有成年单尖、双尖和三尖牙齿的丽鱼科物种的野外数据，来证明一排牙齿的数量与牙齿形状之间存在强烈的正相关关系。我们在旨在解释哺乳动物牙齿形状变异发育基础的形态发生模型的背景下讨论丽鱼科牙齿的个体发育。我们认为，丽鱼科牙列的巨大差异可以通过在牙发生多个阶段起作用的常见激活剂和抑制剂表达的变化来解释。
