Asymmetry of mandibular dentition is associated with dietary specialization in snail-eating snakes.
Asymmetry of mandibular dentition is associated with dietary specialization in snail-eating snakes.
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作者：
Hoso M
在脊椎动物中，左右对同源器官通常以相等的数量存在。一个显着的例外是白腹蛇科的食蜗牛：几乎所有白腹蛇的右下颌上的牙齿都比左下颌多得多，以实现功能专门化，以捕食大多数右侧的陆地蜗牛。由于唯一具有对称齿列的特殊物种被认为是食蛞蝓，因此对蛞蝓的饮食专业化程度可能会影响下颌牙列横向不对称（齿列不对称）的程度，即使在食蜗牛中也是如此。为了验证这一点，我比较了两种同域的台湾食螺蛇——泰雅蛇和台湾食螺蛇的形态和行为。同地采集的标本显示，台湾对虾的齿列不对称性明显小于泰雅对虾。与它的弱不对称性相一致，台湾 P. formosensis 在摄食实验中表现出对蛞蝓的强烈偏好，而不是对蜗牛的偏好。台湾对虾对蛞蝓的饮食特化将有助于其与同域同源泰雅对虾的生态位划分。这项研究表明，白蛇齿列不对称性的多样性变化是其饮食专门化和差异的结果。
In vertebrates, the left-and-right pairs of homologous organs are generally present in equal numbers. A remarkable exception is snail-eating snakes in the family Pareidae: almost all the pareid snakes have much more teeth on the right mandible than on the left for functional specialization in feeding on the dextral majority of land snails. Because the only exceptional species with symmetric dentition has been regarded as a slug-eater, the extent of dietary specialization on slugs could shape the degree of the lateral asymmetry of mandibular dentition (dentition asymmetry) even among snail eaters. To test this, I compared the morphology and behavior of two sympatric species of Taiwanese snail-eating snakes, Pareas atayal and P. formosensis. Specimens collected in the same locality showed that the dentition asymmetry of P. formosensis was significantly smaller than that of P. atayal. Congruent to its weak asymmetry, P. formosensis showed a strong preference of slugs to snails in the feeding experiment. The dietary specialization of P. formosensis on slugs would contribute to niche partitioning from the sympatric congener P. atayal. This study suggests that the diverse variation in the dentition asymmetry of pareid snakes is the result of their dietary specialization and divergence.