Population structure in the highly dispersed southern rock lobster, Jasus edwardsii

The southern rock lobster, Jasus edwardsii, is a species of economic importance in Australia and New Zealand. Due to the extended pelagic larval stage of J. edwardsii, there are predictions of extensive gene flow between... [ view full abstract ]

The southern rock lobster, Jasus edwardsii, is a species of economic importance in Australia and New Zealand. Due to the extended pelagic larval stage of J. edwardsii, there are predictions of extensive gene flow between sub-populations throughout its geographical distribution. Understanding the degree of gene flow and population structure is essential in determining population boundaries, as well as sources and sinks of larvae and will ultimately help in making managerial decisions about fishing effort. The aim of this study was to investigate population structure of J. edwardsii between Australia and New Zealand, using single nucleotide polymorphisms (SNPs). Lobsters were sampled from four locations in Australia (Victoria, West Tasmania, South Tasmania and East Tasmania) and four locations in New Zealand (Auckland, Tonga Island, Chatham Islands and Stewart Island). Baited pots were deployed at each site and left overnight. Pots were collected the following day and lobsters were removed manually from them. Carapace length of all lobsters was measured and either a pleopod clip or a leg was taken and preserved in ethanol. DNA was extracted from a total of 103 individuals and was subject to double-digest restriction site associated DNA sequencing (ddRAD-seq). Libraries were sequenced using the Illumina MiSeq platform. De novo assembly of the reads yielded a panel of 99 SNPs, from which 68 putatively neutral and 31 adaptive SNPs were identified. Genetic structure between populations was investigated using both SNP panels, but only the outlier SNP panel showed significant differentiation between populations (FST=0.036, P<0.001). These results, together with complimentary Discriminant Analysis of Principal Components, which also demonstrated population-specific clustering, are consistent with local adaptation and therefore population structure between the two countries. These results show the utility of low cost next generation sequencing on the Illumina MiSeq platform for detecting population structure between subpopulations in Australia and New Zealand.