Abstract
The genetic structure of natural populations of Misgurnus anguillicaudatus in Ehime Prefecture and the impact of introduced specimens were investigated by partial mitochondrial DNA sequence analysis. A total of 452 specimens from 59 samples were analyzed, comprising 49 populations from eight Prefectures (including 38 from Ehime Prefecture), six populations from Korea, and four samples of food material and fish bait obtained in Ehime Prefecture. Fifty-one haplotypes were identified, falling into two large clades (B-1 and B-2; average nucleotide divergence: 4.2 0.6%), which formed a sister lineage of Paramisgurnus dabrianus (bootstrap value: 100%). Among clade B-1 members, the haplotypes from 25 populations representing 15 water systems in Ehime Prefecture revealed genetic divergence correlated with their geographic distribution (nucleotide divergence distance: 0.3-4.0%). The maximum parsimony network of these haplotypes suggested one major haplotype (89% of the clade’s individuals in Ehime Prefecture) with genetically close satellites present in specific rivers or locations. Some divergent haplotypes, somewhat similar to haplotypes from other Prefectures or from Korea, may have resulted from artificial introductions into Ehime. In clade B- 2, five of the 17 haplotypes were distributed in only four river systems in Ehime Prefecture, without any apparent relation to geographic features, and showed genetic identity or closeness to haplotypes of imported and commercial (food material, fish bait) lines. These results are strongly indicative of recent artificial introductions of alien individuals into natural waters in Ehime Prefecture, resulting in serious genetic disturbances.* Corresponding author: Tarumi Branch, South Ehime Fisheries Research Center, Ehime University, Tarumi, Matsuyama, Ehime 790-8566, Japan (e-mail: takagi@agr.ehime-u.ac.jp)
