Genetic diversity of hydrothermal-vent barnacles in Manus Basin

• Genetic markers are useful tools for understanding biodiversity.
• We assessed COI diversity of two vent-associated barnacles within Manus Basin.
• The barnacle Eochionelasmus ohtai manusensis comprises a single genetic group.
• Two genetically divergent groups were identified in Vulcanolepas cf. parensis.

We evaluated mitochondrial cytochrome oxidase I genetic diversity of two barnacle species (Eochionelasmus ohtai manusensis, Vulcanolepas cf. parensis) at three sites in Manus Basin (Solwara 1, South Su, Solwara 8). There was no evidence for within-site or between-site genetic differentiation for either species. While E. ohtai manusensis showed limited genetic variation, V. cf. parensis showed greater variation, with sequences distributed between two divergent groups. Assuming the cytochrome oxidase I gene is not under selection, significantly negative Tajima′s D in E. ohtai manusensis is consistent with a recent population expansion due to a bottleneck or founder effect, whereas V. cf. parensis (combined groups) did not depart from a stable effective population size. Considering the groups separately, V. cf. parensis Group 1 (but not Group 2) showed a negative Tajima′s D, indicating these groups may have encountered different historical demographic conditions. Data reported here are part of a baseline study against which recovery of genetic diversity following mineral extraction at Solwara 1 can be measured.