Figure 2: Genetic variability in Manila clam populations.

(a) Nucleotide diversity estimated from the whole set of COI sequences (grey bars), and from the clade A sequences only (white bars). Lack of a white bar in some populations indicates the absence of clade A, not zero diversity. The averages across populations are shown as a horizontal thick line (all clades) or a dashed one (clade A). (b) Heterozygosity at microsatellites. The horizontal black line shows the average across populations. (c) Allelic richness at microsatellites. In all figures, alternate white and gray backgrounds separate groups of populations belonging to different geographic regions (China, Japan, North America, Europe).