STRUCTURE bar plots.

<p>Each individual is represented by a vertical bar whose colors show the probability to be assigned to specific clusters. Populations are separated by vertical black lines and identified by the numbers at the bottom (<a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003829#pntd.0003829.g001" target="_blank">Fig 1</a> and <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003829#pntd.0003829.t001" target="_blank">Table 1</a>). K = number of genetic clusters. Overall, a low level of genetic structure was detected. At K6 and K9 most populations from busy ports show genetic admixture, while most populations from idle ports are genetically clustered (compare with <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0003829#pntd.0003829.g003" target="_blank">Fig 3</a>).