Microsatellite DNA markers and morphometrics reveal a complex population structure in a merobenthic octopus species (Octopus maorum) in south-east Australia and New Zealand

Five polymorphic microsatellite loci were developed and then used to assess the population genetic structure of a commercially harvested merobenthic octopus species (Octopus maorum) in south-east Australian and New Zealand (NZ) waters. Beak and stylet morphometrics were also used to assess population diVerentiation in conjunction with the genetic data. Genetic variation across all loci and all sampled populations was very high (mean number alleles = 15, mean expected heterozygosity = 0.85). Microsatellites revealed signiWcant genetic structuring (overall FST = 0.024, p < 0.001), which did not Wt an isolation-by-distance model of population diVerentiation. Divergence was observed between Australian and NZ populations, between South Australia and north-east Tasmania, and between two relatively proximate Tasmanian sites. South Australian and southern Tasmanian populations were genetically homogeneous, indicating a level of connectivity on a scale of 1,500 km. Morphometric data also indicated signiWcant diVerences between Australian and NZ populations. The patterns of population structuring identiWed can be explained largely in relation to regional oceanographic features