Metabarcoding reveals high-resolution biogeographical and metaphylogeographical patterns through marine barriers

Abstract

Aim: It has been predicted that there should be concordance between biogeographical and phylogeographical processes structuring multi-species regional assemblages. We hypothesise that oceanographic barriers in the marine environment affect concomitantly the distribution and the connectivity of the marine biota, thus producing congruent biogeographical and phylogeographical structures. We also predict that macro- and meio-eukaryotes will be differentially affected by hydrological features. Location: The Atlanto-Mediterranean transition along the E Iberian coast marked by the Almeria-Oran Front (AOF) and the Ibiza Channel hydrological discontinuities. Taxon: Eukaryotes.<p> <p>Methods: A new analytical framework based in the metabarcoding of community DNA and a hypervariable marker is presented. This framework allows the simultaneous detection of multispecies biogeographical and phylogeographical structures. Shallow hard-bottom communities were sampled at 12 sites over the littoral zone and community-DNA metabarcoding was performed using the cytochrome c oxidase I marker. The resulting dataset was analysed at several levels: beta diversity of Molecular Operational Taxonomic Units (MOTUs) as surrogate for species, and Exact Sequence Variants as surrogate for haplotypes. We also assessed genetic differentiation within MOTUs (metaphylogeography). Analyses were performed for the combined dataset and separately for macro- and meio-eukaryotes. <p>Results: Both hydrological discontinuities had a detectable effect, more marked at all levels for the AOF than for the Ibiza Channel. The MOTU dataset provided more clear-cut patterns than the ESVs. The metaphylogeographical approach provided the highest resolution in terms of differentiating localities and identifying geographical barriers. The separate analyses of macro- and meio-eukaryotes showed a higher differentiation of the latter, both in terms of beta diversity and genetic differentiation. <p>Main Conclusions: Metabarcoding coupled with metaphylogeography allowed the characterisation of the heterogeneity in community composition and population genetic structure along the Atlanto-Mediterranean transition, coherent with known hydrological discontinuities. This methodology unlocks a vast amount of information on the geographical distribution of different components of biodiversity for basic and applied research.