Intraspecific invasion occurring in geographically isolated populations of the Japanese cyprinid fish Zacco platypus

Kenzi Takamura,Mayuko Nakahara

doi:10.1007/s10201-015-0450-y

Abstract

Geographically isolated populations of freshwater fish have been introduced into conspecific native populations. One of the most representative cases is the pale chub Zaccoplatypus. The pale chub of Lake Biwa in western Japan has been inadvertently introduced to other waters with the release of game fish. Because they are not clearly discriminated from other populations by their morphological characteristics, the morphological detection of the colonization is not possible. Hence, a genetic analysis of fish collected from rivers of the Kanto Plain in eastern Japan, where the introduction was made, was conducted. The haplotype variety of the mitochondrial gene cytochrome b of the fish revealed the presence of two major groups of haplotypes. We concluded that one of the groups was introduced from western Japan, especially Lake Biwa, and the other was native to the Kanto Plain. The haplotypes from western Japan were established in all of the rivers studied and occurred together with the native haplotypes in the rivers within the original distribution range of the species. The allelic composition of microsatellite loci indicated that fish from the two different sources were well admixed through hybridization in the populations of the rivers of the Kanto Plain.

Highlights

Intraspecific invasions occur when introduced organisms belong to a sister species, subspecies, or intraspecific groups, which are defined by prominent genetic gaps in haplotypes [intraspecific phylogroup (Avise 2000)] with any native organisms
Group II contained all of the haplotypes we have found from specimens of Lake Biwa
Both this analysis and our results indicate that haplotypes of group I are native to the Kanto Plain and that those haplotypes of group II were introduced from western Japan, especially Lake Biwa

Summary

Introduction

Intraspecific invasions occur when introduced organisms belong to a sister species, subspecies, or intraspecific groups, which are defined by prominent genetic gaps in haplotypes [intraspecific phylogroup (Avise 2000)] with any native organisms. Fish have been introduced to non-native areas through activities such as fishery, game fishing, ornamental trade, or habitat restoration (Lever 1996; Gozlan et al 2010). When this introduction occurs where native populations of the same species are present, intraspecific invasion can occur. The resultant situation is often the colonization of the introduced population and/or the hybridization with native populations [e.g., marine bluestriped snapper (Gaither et al 2010); riverine brown trout (Hansen et al 2009)] This colonization has occurred deliberately as a target species and inadvertently as an accompanying species

Methods

Results

Conclusion