Clarification of current distribution and ecological factors for successful localization in the two invasive freshwater apple snails, the genus Pomacea

研究了东亚和东南亚两种入侵苹果螺Pomacea canaliculata和P. maculata的分布现状，以及限制其分布区域的生态因素。管状Pomacea cananaliculata广泛分布于东南亚至日本温带地区（关东平原），而maculata的北部分布界限为Iriomote岛。结果表明，小管螺蛳和斑纹螺蛳可以杂交，并在田间发现了杂交螺。杂交钉螺的分布范围介于两种钉螺之间，以韩国釜山为北界。造成不同种间和杂交种间分布范围不同的最重要因素是对冬季低温的耐受程度不同。

We clarified current distribution of two invasive apple snails, Pomacea canaliculata and P. maculata in East and Southeast Asia, and ecological factors restricting their distribution area. Pomacea canaliculata were distributed widely from Southeast Asia to temperate Japan (Kanto Plain), whereas northern disrbitution limit of P. maculata was Iriomote Island. We demonstrated that P. canaliculata and P.maculata could hybridize and found the hybrid snails in field. The hybrid snails had an intermediated distribution range between the two snails with a northern distribution limit of Pusan, Korea. The most important factor causing the different distribution ranges among the species and hybrids were considered to be the different degrees of tolerance to low temperature during winter.