Figure Captions

Fig. 1. Map showing study area and 11 sampling locations in Beibu Gulf, South China Sea.
Fig. 2. Haplotype network for Evynnis cardinalis on the basis of nucleotide variation at the cytochrome c oxidase subunit I (COI) gene. Each circle represents a unique haplotype, and its size is proportional to the number of individuals sharing that specific haplotype. For each branch with more than one mutational step each mutational step is labelled.
Fig. 3. Pie diagrams showing the relative abundance of different haplotypes across the eleven sampling sites (total number of different haplotypes = 44). The size of each pie fraction is proportional to the fraction of individuals with a given haplotype.
Fig. 4. Observed mismatch distributions (bars) and expected mismatch distributions under sudden expansion model (line) of COI forEvynnis cardinalis from Beibu Gulf
Fig. 5. Bayesian skyline plot revealing the demographic trends ofEvynnis cardinalis in Beibu Gulf. The dark solid line is median estimate under the assumption of per site mutation rate of 2% per million years. The dark gray solid line shows the median obtained under the assumption of per site mutation rate of 1% per million years, while the light gray bottom line shows the median obtained under the assumption of per site mutation rate of 3% per million years, and the dashed lines show the 95% highest posterior density (HPD) limits.