to five or ten did not significantly change the results (data
not shown). Although there was weak but significant
genetic differentiation according to the F ST values, the
Bayesian clustering analysis indicated that the most likely
K was one.
Sequencing a part of the mtDNA control region revealed
that there were only two haplotypes, Gj1 and Gj2, with
predominance of the latter (88 %) (Fig. 1). This result was
consistent with the previously reported findings (Hasegawa
et al. 1999). It appears that the two haplotypes were dis-
tributed across the whole range without any clear spatial
pattern (Fig. 1).
Discussion
The group-level analyses found low pairwise F ST values
and no significant differences in genetic diversity, probably
because of the population expansion in the recent past;
however, the spatial autocorrelation analysis indicates a
pattern of isolation by distance. This finding is unexpected