Maps of gene flow and median-joining network (Insert) for each studied species. Map of the China coast showing sampling sites and estimated number of migrants per generation between groups (Nm) for each species. All sampling sites of each species are divided into Yellow Sea (YS) group and East plus South China Seas (ESCS) group according to the Yangtze River Estuary. The black dots represent sampling localities for each species. The blue circle and red circle represent the relative magnitude of Θ
YS (YS group) and Θ
ESCS (ESCS group) respectively. The blue and red arrows represent the direction and relative magnitude of gene flow estimates between groups. Inset: Haplotype network obtained with mitochondrial DNA for each species and nuclear DNA for S. japonica. Each circle represents a single haplotype and sizes are proportional to the number of individuals possessing these haplotypes. Haplotypes of each species are divided into the Yellow Sea (YS) group and the East and South China Seas (ESCS) group separated by the Yangtze River estuary. Colors represent group where haplotypes were detected (blue, YS group; red, ESCS group). The small white circles indicate hypothetical missing haplotypes. Reference: Cellana toreuma, Dong et al. ; Sargassum horneri, Hu et al. ; Atrina pectinata, Liu et al.