GEOGRAPHIC-VARIATION AND DIVERSITY IN THE MITOCHONDRIAL-DNA OF THE MEDAKA, ORYZIAS-LATIPES, AS DETERMINED BY RESTRICTION-ENDONUCLEASE ANALYSIS

Analysis of mitochondrial DNA (mtDNA) restriction fragment length poly morphism in Japanese wild populations of the medaka, Oryzias latipes r evealed a large number of mtDNA haplotypes that form three distinct cl usters (clusters A, B and C). The average nucleotide diversities among these three clusters are 8.9% (A versus B), 8.4% (A versus C), and 7. 3% (B versus C). Cluster A consists of seven haplotypes and was subdiv ided into two subclusters. The nucleotide diversity in cluster A is lo w, ranging from 0.3% to 1.4% (mean 0.8%). Cluster B has 55 haplotypes and was subdivided into 11 subclusters. The nucleotide diversity in cl uster B is high, ranging from 0.1 to 4.8% (mean 1.5%). Cluster C consi sts of only one haplotype, found in two sites of the Kanto district. T he geographic distributions of mtDNA haplotypes in clusters A and B ap pear fully concordant with the previously described ranges of the Nort hern Population and the Southern Population defined by allozymes. More over, the distributions of mtDNA haplotypes in the subclusters show st rong geographical associations. The distribution patterns of mtDNA hap lotypes suggest some migration events of the medaka.