Haplotype network
In the haplotype network for COI, haplotype 1 was predominant in the Korean L morph samples, accounting for 40.0% of samples (58 individuals), including 41.4% of samples in region A, 32.8% in region C, 17.2% in region B, and 8.6% in region D (Figure 1). The USA samples belonged to haplotype 36 (Figure 1). Six haplotypes (haplotypes 1, 2, 4, 7, 17, and 34) were distributed in two or more regions and the other haplotypes were restricted to unique regions. Seventeen haplotypes were derived from haplotype 1, and 16 of these differed by a singleton mutation (Figure 1). Haplotype networks for COII and Cytb showed similar haplotype distribution patterns to that for COI (Figure S1). For all three genes, the Korean S morph haplotypes were more closely related to Japanese haplotypes than to the dominant L morph haplotypes in Korea (Figure 1 and S1).