First Assessment of Genetic Diversity, Phylogeographic Relationships, and Population Structure of the Brown Seaweed Ericaria amentacea From Italian Coasts Using Cytochrome Oxidase Subunit I (COI) Gene

Ericaria amentacea is an endemic key seaweed species in the coastal ecosystem of the Mediterranean basin. Given its ecological role and sensitivity to environmental conditions decline, it has been designated as a protected species. Scarce local population genetic studies have been performed on this species on Italian coasts. For the first time, mitochondrial cytochrome oxidase subunit I (COI-5P) gene was amplified and analyzed for 42 italian E. amentacea specimens, collected from five localities along Ligurian and Sardinian coasts. In addition, nine COI-5P sequences were retrieved from National Center for Biotechnology Information (NCBI) investigating South Italy coasts. Polymorphism results revealed high values of haplotype diversity (Hd) and very low nucleotide diversity (π). Thus, these results suggest that our E. amentacea populations may have undergone a genetic breakdown followed by rapid demographic expansion. This inference is strongly confirmed by the results of neutrality tests and “mismatch distribution”. The important number of haplotypes between localities and the high genetic differentiation (Fst = 0.79) of the current E. amentacea populations could be maintained by the limited gene flow Nm (0.48). Moreover, results indicated that genetic variation is high, with most of it distributed among populations (79.39%). Both haplotype Network and biogeographic analysis showed a structured distribution according to the geographic origin. E. amentacea populations are subdivided into mainland versus insular populations. Indeed, these findings have important implications for conservation and restoration actions to counteract the potential decline of E. amentacea populations that require a deep knowledge of their genetic structure.