Multiple origins of invasive and ‘native’ water frogs (Pelophylaxspp.) in Switzerland

Abstract

The marsh frog (Pelophylax ridibundus) has been introduced in many areas in Central and Western Europe as a result of commercial trade with Eastern Europe, and is rapidly replacing the native pool frog (P. lessonae). A large number of Pelophylax species are distributed in Eastern Europe and the strong phenotypic similarity between these species is rendering their identification hazardous. Consequently, alien populations of Pelophylax 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 Pelophylax species from Switzerland (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 Switzerland. Unexpectedly, we also showed that several populations of the native pool frog (P. lessonae) cluster with the Italian pool frog P. bergeri from central Italy (considered by some authors as a subspecies of P. lessonae). Hence, these populations are probably also the result of introductions, meaning that the number of native P. lessonae populations is fewer than expected in Switzerland. 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.

Once a land of big wild rivers: specialism is context-dependent for riparian snails (Pulmonata: Valloniidae) in central Europe

“…The extinction of native species and the spread of invasive ones impose a heavy toll on ecological restoration (e.g. Dubey, Leuenberger & Perrin, ). In my experience, too many European freshwater ecologists have never seen, or even conceived, a wild river with its native fauna.…”

A reference DNA barcode library for Austrian amphibians and reptiles

“…This also implies, that neither a BLAST search on GenBank or BOLD, nor the accumulation of further COI data of these PLOS ONE PLOS ONE species will result in an unambiguous identification, unless this data is supported and verified by additional analyses (e.g. PCR-RFLP [52]; microsatellite data [53][54]; PCR-sequence length differences [55]). On the other hand, DNA barcoding revealed the mitochondrial signature of the Italian water frog P. bergeri in one of our samples (Fig 3) collected in Vorarlberg in the far West of Austria for the first time.…”

Estimating Effects of Species Interactions on Populations of Endangered Species

“…As far as possible, individuals of the water frog complex were identified as either Eurasian marsh frogs (Pelophylax ridibundus) or pool frogs (Pelophylax lessonae) including hybrids (Pelophylax esculentus), on the basis of morphological characteristics or their calls (Laufer et al 2007). However, because of the strong phenotypic similarity of Eurasian marsh frogs, pool frogs, and their hybrids, unambiguous identification in the field is often impossible (Dubey et al 2014). We therefore pooled the data on Eurasian marsh frogs, pool frogs, and their hy-brids before analyses and used the name "water frog" for all of them.…”