Genetic differentiation of ezo brown frog (Rana pirica Matsui, 1991) (Anura: Ranidae) on Pacific islands

Abstract

The mechanisms of colonization of islands by ver� tebrates it a topical problem of zoogeography and the theory of evolution. A promising approach to solving this problem is the genetic analysis of taxonomically close forms inhabiting the mainland and the neighbor� ing islands separated from the latter at different time. This is the first study to reconstruct the pathway of colonization of Pacific islands by brown frogs on the basis of analysis of the sequence of the mitochondrial gene encoding cytochrome c oxidase I of related spe� cies combined with geographical data. It is assumed that gene flow between the geographical populations of Rana pirica inhabiting Kunashir, the Smaller Kuril Chain, and Hokkaido took place after the separation of Sakhalin Island. Until recently, the taxonomic status and the num� ber of species of brown frogs of Sakhalin and Kuril islands was the subject of discussions (for review, see [2]). This especially applies to the brown frogs of the R. chensinensis complex. The study of sequences of the gene for mitochondrial cytochrome b showed that the frogs of this group from the southern Sakhalin are almost identical to R. pirica (Matsui, 1991) from Hok� kaido and significantly differ from R. dybowskii (Guenther, 1876) from Primorie. It is believed that Hokkaido, Sakhalin, and South Kuril islands are inhabited by R. pirica, whereas the mainland part of the Far East of Russia and some offshore islands are inhabited by R. dybowskii, although the genetics of the populations inhabiting the South Kuril islands has not been studied. At the same time, the morphological dif� ferences between the Sakhalin, Hokkaido, and Kuril populations of R. pirica as well as certain morphologi� cal similarity of the Sakhalin populations of this frog with R. dybowskii from Khabarovsk krai leave the issue on the genetic differentiation pattern and subspecies structure of R. pirica to be elucidated.