Genetic insights into recolonization processes of Mediterranean octocorals

Marine ecosystems are strongly impacted by the consequences of human activities, such as climate change and habitat destruction or artificialization. In the Mediterranean Sea, sessile benthic species, and particularly octocorals, have been affected by mass mortality events linked with temperature anomalies. The future evolution of octocorals facing global change will depend on their recolonization abilities facing local extirpation or important modification of their habitat. We studied these processes in Mediterranean octocorals in two situations: the colonization of artificial substrates (wrecks) by the red gorgonian Paramuricea clavata, and the recolonization following mortality events in the yellow gorgonian Eunicella cavolini. With microsatellite markers, we analyzed the genetic diversity of these populations and their differentiation from other neighboring populations. For P. clavata the populations on artificial substrates were not or lowly differentiated from the closest populations on natural substrates, and with similar levels of genetic diversity. Artificial substrates can then be considered as an interesting substitute for natural substrates for this species. For E. cavolini we did not detect any variation in diversity nor relatedness following recuperation after mortality events. In both cases our results suggest input from different populations in recolonization process, which helps in maintaining genetic diversity. These results are useful for the management of these species and of associated ecosystems. The data are presented in two files, one for each species, at the Genepop format (https://kimura.univ-montp2.fr/~rousset/Genepop.htm). Some alleles have been recoded and do not correspond to the original PCR size so this dataset can not be used with methods based on allele size