북태평양 연어 집단간의 개체 이동에 의한 유전자 교환

Abstract

The chum salmon (Oncorhynchus keta) is an anadromous fish distributed in the North Pacific. Artificial production and release of its juveniles are being made in the hatcheries of Korea, Japan, Russia, Canada and the United States. It has been a common belief that the released salmons return back to their home rivers when they become mature. As an attempt to examine the extent of their homing behavior, here we inferred the phylogenetic relationships among the individuals of different populations and estimated the rate of gene flow between the populations. For this, sequences of the COIII-ND3-ND4L region (744 nucleotides) of the mitochondrial DNA were obtained from Korea (35 individuals, Namdae river; 13, Wangpi river), Japan (20, Hakodade; 24, Shokanbetsu river), Canada (14, Nitnat river; 15, Fraser river), and the United States chum salmons (20, Quilcene). The 141 individuals constitute 45 different haplotypes of which a haplotype is shared by approximately 50% of Korea and Japan individuals, a haplotype by Japan and Canada, a haplotype by Canada and the United States, and a haplotype by individuals from all of the four populations, indicating the presence of migration among the populations. The network diagram of the haplotype genealogies corroborates such gene flow and shows the close relationships between the Korea and the Japan populations and between the Canada and the United States populations. The major gene flow is observed from the United States to Canada populations (250±150 individuals per generation, p<0.05), and other gene flows from Canada to Korea and between Canada and Japan populations.