Divergent Shell Shape as an Antipredator Adaptation in Tropical Land Snails
Divergent Shell Shape as an Antipredator Adaptation in Tropical Land Snails
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DOI：
10.1086/591681
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发表时间：
2008-11-01
影响因子：
2.9
通讯作者：
Hori, Michio
中科院分区：
文献类型：
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作者：
Hoso, Masaki;Hori, Michio
尽管许多陆地蜗牛在热带地区表现出惊人的不同外壳形状，但这些蜗牛的功能仍然不清楚。在这里，我们展示了修改后的孔径形状专门针对食蜗牛的捕食起到了障碍作用。 Pareas iwasakii（游蛇科：Pareatinae）使用一种独特的方法来捕食陆地蜗牛：蛇通过交替缩回下颌，通过孔将柔软的身体从壳中取出。 Satsuma caliginosa 蜗牛（Camaenidae：Camaeninae）在食蜗牛蛇的存在方面存在孔径变化。我们的实验表明，扭曲的光圈机械地阻碍了这种张口受限的捕食者的捕食，中断了下颌运动。相比之下，具有圆孔的同类蜗牛却未能逃脱蛇的捕食。焦点区域的古生物地理学表明，不具有孔径修饰的Satsuma caliginosa picta亚种源自食螺蛇灭绝后的防御祖先。我们的研究表明，吃蜗牛的蛇可能是造成各种热带陆地蜗牛壳形状不同的原因。
Although many land snails exhibit amazingly divergent shell shapes in the tropics, the functions of these remain obscure. Here we show that a modified aperture shape acts as an impediment specifically to predation by a snail-eating snake. Pareas iwasakii (Colubridae: Pareatinae) uses a unique method to feed on land snails: the snake extracts the soft body from the shell through the aperture by alternately retracting its mandibles. The snail Satsuma caliginosa (Camaenidae: Camaeninae) has apertural variation in regard to the presence of snail-eating snakes. Our experiments demonstrated that the distorted aperture mechanically impeded predation by this gape-limited predator, interrupting the mandibular movements. In contrast, congeneric snails with round apertures did not escape predation by snakes. The paleobiogeography of the focal area indicates that the subspecies Satsuma caliginosa picta, which does not have apertural modification, was derived from a defensive ancestor after the extinction of snail-eating snakes. Our study suggests a possibility that snail-eating snakes are responsible for divergent shell shapes in a variety of tropical land snails.