Danaisawadi Patchara, Asami Takahiro, Ota Hidetoshi, Sutcharit Chirasak, Panha Somsak
Biological Science Program, Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand.
Animal Systematics Research Unit, Department of Biology, Chulalongkorn University, Bangkok 10330, Thailand.
Sci Rep. 2016 Apr 5;6:23832. doi: 10.1038/srep23832.
Specialized predator-prey interactions can be a driving force for their coevolution. Southeast Asian snail-eating snakes (Pareas) have more teeth on the right mandible and specialize in predation on the clockwise-coiled (dextral) majority in shelled snails by soft-body extraction. Snails have countered the snakes' dextral-predation by recurrent coil reversal, which generates diverse counterclockwise-coiled (sinistral) prey where Pareas snakes live. However, whether the snake predator in turn evolves any response to prey reversal is unknown. We show that Pareas carinatus living with abundant sinistrals avoids approaching or striking at a sinistral that is more difficult and costly to handle than a dextral. Whenever it strikes, however, the snake succeeds in predation by handling dextral and sinistral prey in reverse. In contrast, P. iwasakii with little access to sinistrals on small peripheral islands attempts and frequently misses capturing a given sinistral. Prey-handedness recognition should be advantageous for right-handed snail-eating snakes where frequently encountering sinistrals. Under dextral-predation by Pareas snakes, adaptive fixation of a prey population for a reversal gene instantaneously generates a sinistral species because interchiral mating is rarely possible. The novel warning, instead of sheltering, effect of sinistrality benefitting both predators and prey could further accelerate single-gene ecological speciation by left-right reversal.
特殊的捕食者 - 猎物相互作用可能是它们共同进化的驱动力。东南亚食蜗牛蛇（棱鳞蛇属）右下颌有更多牙齿，专门通过软体提取捕食壳类蜗牛中大多数顺时针螺旋（右旋）的个体。蜗牛通过反复的螺旋反转来应对蛇的右旋捕食，这在棱鳞蛇生活的地方产生了各种逆时针螺旋（左旋）的猎物。然而，蛇捕食者是否会反过来对猎物的反转进化出任何反应尚不清楚。我们发现，与大量左旋蜗牛生活在一起的棱鳞蛇会避免接近或攻击比右旋蜗牛更难处理且成本更高的左旋蜗牛。然而，每当它发起攻击时，蛇通过以相反的方式处理右旋和左旋猎物而成功捕食。相比之下，在小外围岛屿上很少能接触到左旋蜗牛的岩崎棱鳞蛇试图捕捉特定的左旋蜗牛时经常失手。对于经常遇到左旋蜗牛的右旋食蜗牛蛇来说，识别猎物的旋向应该是有利的。在棱鳞蛇的右旋捕食下，猎物群体中反转基因的适应性固定会立即产生一个左旋物种，因为左右旋之间很少能交配。左旋的这种新的警示作用而非庇护作用对捕食者和猎物都有益，可能会通过左右反转进一步加速单基因生态物种形成。
