Phylogeography of Phycodrys rubens (Linnaeus) batters from mainland Norway and Svalbard based on nuclear and mtDNA sequences and microsatellites

Phycodrys rubens is a common cold temperate red macroalga in the North Atlantic, a region with a diverse natural history that has shaped the phylogeography for many species. In this study microsatellite loci as well as nuclear and mtDNA sequences were used to investigate the phylogeography and populations genetic diversity of P. rubens in the northern North Atlantic. A total of 19 mtDNA cox2-3 intergenic spacer sequences and 37 nrDNA ITS1 sequences were obtained representing 15 locations in Svalbard, Norway and Iceland. In addition 103 individuals from two locations each on Svalbard and outside Bergen were analysed for five microsatellite loci. Several unique haplotypes were identified among the cox2-3 spacer sequences, and 10 (53%) of the haplotypes were found only once. The analysed ITS1 sequences were less variable, and all ITS1 sequence types were found in more than one populations. The geographic distribution of the ITS1 sequences types, with most being shared among geographically widespread populations, suggests a recent common history of populations that are currently widespread. The ITS1 sequences obtained in this study all represented the East Atlantic lineage as identified by van Oppen et al (1995). Some of the ITS1 and cox2-3 sequence types and microsatellites genotypes occurred only in mainland Norway or only in Svalbard, indicating isolation of the current populations of P. rubens. From one to four genotypes were identified from each of the five microsatellite loci used, three of the loci had three genotypes, while one locus had four genotypes and the last locus was monomorphic in the tested populations. Three of the tested microsatellite loci gave good resolution and were usable to look at population differences between Svalbard and Bergen. For the microsatellite loci there were differences in genotype frequencies, both between the populations of Svalbard and Bergen, but also between the two populations in each Svalbard or Bergen. For instance two of the genotypes found were only present in one population.MAMN-MARMAR39