Paleobiology of heterodont bivalves based on polymorphism of the hinge-teeth

对异齿双壳类心脏科、棘心科、克拉萨特利科、Astartiate、斜齿科、心脏科、龟科和性瓣科的铰链转位进行了研究，结果表明，除棘心科、心脏科、龟科和性瓣科外，所有异齿双壳类的铰链转位都很少，主要不到1.0%。所有前侧齿错位的瓣膜都有同种瓣膜上的基牙移位，任何前侧牙正常的瓣膜都有正常的基牙。在这些家系中，前侧牙和基牙可能是一个单一的遗传联系的单一单位，而后侧牙可能是另一个单位。每个单位都有两种表型，即正常牙列和易位牙列。因此，通过两个单位和两个表型的组合，异齿双壳类中预计会有四种类型的牙列。与解剖和贝壳不对称的腹足类整体转位相比，部分转位在双壳类中相当常见。部分转位可能是由它们的对称组织引起的，并且可以选择性地接近中性。腹足类的整体易位可能导致生殖隔离，异齿双壳类的部分易位带来了物种内高度的遗传多样性。

A study of hinge transposition in the heterodont bivalve families Carditidae, Condylocardiidae, Crassatellidae, Astartidate, Trapezidae, Cardiidae, Tellinidae, and Veneridae, showed that all these families except Condylocardiidae, Cardiidae, Tellinidae, and Veneridae rarely have transposed hinges, mainly less than 1.0%.Any valve with transposed anterior lateral teeth had transposed cardinal teeth on the same valve, and any valve with normal anterior lateral teeth always had normal cardinal teeth. The anterior lateral teeth and the cardinal teeth may be a single genetically linked single unit in these families, and the posterior lateral teeth another unit. Each unit is represented by two phenotypes, namely normal and transposed dentition. With a combination of two units by two phenotypes, therefore, four types of dentition are expected in the heterodont bivalves.In contrast to a whole transposition of gastropods with anatomical and shell asymmetry, a partial transposition is fairly common within the bivalves. The partial transposition may be caused by their symmetrical organization and may be selectively nearly neutral. The whole transposition in gastropods may lead to reproductive isolation, the partial transposition in heterodont bivalves brings high genetical diversity within a species.