New insights on the phylogenetic position and population genetic structure of the Critically Endangered Karpathos marsh frog Pelophylax cerigensis (Amphibia: Anura: Ranidae)

Abstract

The genus Pelophylax, which currently comprises 26 species, is a well studied group due to its complex history and high diversification, although some phylogenies remain unresolved. Here we assess the phylogenetic position and the population genetic structure of the Critically Endangered Karpathos frog, Pelophylax cerigensis, endemic to Karpathos Island. A total of 42 cytb sequences were examined including specimens from Rhodes Island, and amplified fragment length polymorphisms (AFLPs) were generated to investigate the genetic structure and connectivity of the only two known populations on Karpathos. Molecular analyses reveal two major waterfrog lineages in the eastern Mediterranean: Clade A comprises Pelophylax bedriagae from the Middle East and the island of Cyprus, while clade B includes both P. bedriagae from the east Aegean Sea and P. cerigensis. Specimens from Karpathos and Rhodes constitute a single clade, contrasting previous studies, thus indicating the occurrence of Karpathos frog also to the neighboring Rhodes. The AFLP markers revealed low but statistically significant levels of genetic divergence between the two Karpathos’ populations and similar levels of genetic diversity. Our results suggest that the current taxonomy of the species should be re-evaluated. We also strongly recommend the need of conservation actions to maintain the levels of diversity in the declining population of the Karpathos frog.