Connectivity, small islands and large distances: the Cellana strigilis limpet complex in the Southern Ocean.

The Southern Ocean contains some of the most isolated islands on Earth and fundamental questions remain regarding their colonisation and the connectivity of their coastal biotas. Here we conduct a genetic investigation of the Cellana strigilis (limpet) complex that was originally classified based on morphological characters into six subspecies, five of which are endemic to the New Zealand (NZ) subantarctic and Chatham islands (44° to 52° S). Previous genetic analyses of C. strigilis from six of the seven island groups revealed two lineages with little or no within-lineage variation. We analysed C. strigilis samples from all seven island groups using two mitochondrial (COI and 16S), one nuclear (ATPase ) and randomly amplified polymorphic DNA markers (RAPDs), and confirmed the existence of two distinct lineages. We also detected pronounced genetic structuring within each lineage, with limpets from each island having their own genetic identity. These results are strikingly congruent with...