Multiple origins of invasive and ‘native’ water frogs ( P elophylax spp.) in S witzerland

The marsh frog ( P elophylax ridibundus ) has been introduced in many areas in C entral and W estern E urope as a result of commercial trade with E astern E urope, and is rapidly replacing the native pool frog ( P . lessonae ). A large number of P elophylax species are distributed in E astern E urope and the strong phenotypic similarity between these species is rendering their identification hazardous. Consequently, alien populations of P elophylax might not strictly be composed of P . ridibundus as previously suspected. In the present study, we analysed the cytochrome‐ b and NADH dehydrogenase subunit 3 genes of introduced and native P elophylax species from S witzerland (299 individuals) in order to properly identify the source populations of the invaders and the genetic status of the native species. Our study highlighted the occurrence of several genetic lineages of invasive frogs in western S witzerland. Unexpectedly, we also showed that several populations of the native pool frog ( P . lessonae ) cluster with the I talian pool frog P . bergeri from central I taly (considered by some authors as a subspecies of P . lessonae ). H ence, these populations are probably also the result of introductions, meaning that the number of native P . lessonae populations is fewer than expected in S witzerland. These findings have important implications concerning the conservation of the endemic pool frog populations, as the presence of multiple alien species could strongly affect their long‐term subsistence. © 2014 T he L innean S ociety of L ondon, B iological J ournal of the L innean S ociety , 2014, 112 , 442–449.