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Figure 4 
(A) A minimum spanning network of haplotypes and (B) a map of the geographic 
distribution of haplotypes based on phylogenetic analysis of the mitochondrial 
cytochrome b gene sequences (931 base pairs) of polkadot skate (Dipturus chin- 
ensis). Sequences were obtained from specimens caught at 7 locations around 
Japan during 2010-2017 or were obtained through the International Nucleotide 
Sequence Database Collaboration for populations in Taiwan or off the Korean 
Peninsula. Circles of different colors represent the 13 major haplotypes. Gray 
circles and circles or slices of circles with horizontal or vertical lines represent 
rare (observed in 1 or 2 individuals) haplotypes in groups A, B1, and B2, respec- 
tively. Isls.=Islands; Penin.=Peninsula; Pref.=Prefecture. 
Fishery Bulletin 119(2—3) 
population in Kyoto Prefecturue, with 
a mean of 8.70. The mean Ap for each 
geographic population varied from 6.01 
for the population in Kochi Prefecture 
to 8.67 for the population in the Goto 
Islands, with a mean of 7.65. The mean 
Ho and Hy per locus varied from 0.484 at 
locus LERI21 to 0.857 at locus LERI44 
and from 0.577 at locus LERI21 to 0.894 
at locus LERI63, respectively. The mean 
Ho per geographic population ranged 
from 0.476 for the population in Kochi 
Prefecture to 0.681 for the population in 
Kyoto Prefecture. The mean Hy per geo- 
graphic population ranged from 0.593 
for the population in Aomori Prefecture 
to 0.804 for the population in the Danjo 
Islands, with heterozygosity gradually 
decreasing from the Danjo Islands in the 
East China Sea northward to Niigata 
Prefecture in the Sea of Japan. Signif- 
icant deviation from the Hardy—Wein- 
berg expectations due to homozygote 
excess was observed at 2 loci (LERI26 
and LERI63). We deduced that these loci 
were affected by null alleles; therefore, 
they were also excluded from further 
analyses. For the 4 SSR loci (LERI21, 
LERI34, LERI44, and LERI50), no evi- 
dence of genotyping errors attributable 
to null alleles, stuttering, or large allele 
drop-out were observed. The results 
of pairwise comparisons between loci 
reveal no linkage disequilibrium. 
Genetic differentiation among popu- 
lations Results from hierarchical 
AMOVA (Suppl. Table 1) (online only) 
indicate that the Rgp value was 0.1409 
(P<0.001) and that 14.09% of genetic 
variability was distributed among the 
6 geographic populations included in 
analysis. When the 6 populations were 
divided into 2 groups, clade A and clade 
B, the Rep value was 0.0868 (P=0.067), 
and 8.68% of genetic variability was 
distributed between the groups. When 
the 6 populations were divided into 
3 groups, clade A, clade B1, and clade 
B2, the Roe, value was maximized 
(Ro7p=0.1359), and 13.59% of genetic 
variability was distributed between the 
groups. However, the value was barely 
not significant (P=0.066). 
The pairwise Rg, values among the 
6 geographic populations estimated for 4SSR loci are shown 
in Table 3. The Rgy values between each of the 2 popula- 
tions in the Pacific Ocean (in the Kochi and Aomori Prefec- 
tures) and each of the 4 populations in the East China Sea 
polymorphism was observed at locus LERI33; therefore, 
this locus was not included in further analyses. The mean 
number of alleles per geographic population ranged from 
6.33 for the population in Kochi Prefecture to 9.83 for the 
