Development of tools to rapidly identify cryptic species and characterize their genetic diversity in different European kelp species

<p>Marine ecosystems formed by kelp forests are severely threatened by global change and local coastline disturbances in many regions. In order to take appropriate conservation, mitigation and restoration actions, it is crucial to identify the most diverse populations which could serve as a "reservoir" of genetic diversity. This requires the development of specific tools, such as microsatellite markers to investigate the level and spatial distribution of genetic diversity.  Here, we tested new polymorphic microsatellite loci from the genome of the kelp, <i>Lamina</i><i>ria digitata,</i> and tested them for cross-amplification and polymorphism in four closely related congeneric species (<i>Laminaria hyperborea, Laminaria ochroleuca, Laminaria rodriguezii and Laminaria pallida</i>). Adding these 20 new microsatellite loci to the ten <i>L. digitata</i> loci previously developed by Billot et al. (1998) and Brenan et al. (2014) and to the ten <i>L. ochroleuca</i> loci previously developed by Coelho et al. (2014), we retained a total of 30 polymorphic loci for <i>L. digitata</i>, 19 for <i>L. hyperborea</i>, 16 for <i>L ochroleuca</i>, 19 for<i> L. rodriguezii</i> and 12 for<i> L. pallida</i>. These markers have been tested for the first time in the last two species. As predicted, the proportion of markers that cross-amplified between species decreased with increasing genetic distance. In addition, as problems of species identification were reported in this genus, mainly between <i>L. digitata </i>and <i>Hedophyllum nigripes</i>,<i> </i>but also between <i>L. digitata, L. hyperborea </i>and<i> L. ochroleuca </i>in areas where their range distributions overlap, we report a rapid PCR identification method based on species-specific cox1 mitochondrial primers that allows these four species of kelp to be rapidly distinguished.</p>