Suchergebnisse

Unidad de excelencia María de Maeztu MdM-2015-0552 ; The study was funded by a 2003-2004 INTERREG project between Catalonia Languedoc Rouissillon "Pirineus Mediterrànis: La muntanya que uneix"' of the CSIC and CNRS, of the 2009-2013 European project LIFE+ INDEMARES "Inventario y designación de la red natura 2000 en áreas marinas del estado español" (LIFE07/NAT/E/000732) of the European Union, and by a PRIN 2010-2011 project (prot. 2010Z8HJ5M) on "Coastal bioconstructions: structure, function and management" Italian Ministry of Education, Univeristy and Research. ; Gorgonian species show a high morphological variability in relation to the environment in which they live. In coastal areas, parameters such as temperature, light, currents, and food availability vary significantly with depth, potentially affecting morphology of the colonies and the structure of the populations, as well as their connectivity patterns. In tropical seas, the existence of connectivity between shallow and deep populations supported the hypothesis that the deep coral reefs could potentially act as (reproductive) refugia fostering re-colonization of shallow areas after mortality events. Moreover, this hypothesis is not so clear accepted in temperate seas. Eunicella singularis is one of the most common gorgonian species in Northwestern Mediterranean Sea, playing an important role as ecosystem engineer by providing biomass and complexity to the coralligenous habitats. It has a wide bathymetric distribution ranging from about 10 m to 100 m. Two depth-related morphotypes have been identified, differing in colony morphology, sclerite size and shape, and occurrence of symbiotic algae, but not in mitochondrial DNA haplotypes. In the present study the genetic structure of E. singularis populations along a horizontal and bathymetric gradient was assessed using microsatellites and ITS1 sequences. Restricted gene flow was found at 30-40 m depth between the two Eunicella morphotypes. Conversely, no genetic structuring has been found among shallow water populations within a spatial scale of ten kilometers. The break in gene flow between shallow and deep populations contributes to explain the morphological variability observed at different depths. Moreover, the limited vertical connectivity hinted that the refugia hypothesis does not apply to E. singularis. Re-colonization of shallow water populations, occasionally affected by mass mortality events, should then be mainly fueled by larvae from other shallow water populations.

Aim: Marine bioconstructions such as coralligenous formations are hotspot of biodi‐ versity and play a relevant ecological role in the preservation of biodiversity by provid‐ ing carbon regulation, protection and nursery areas for several marine species. For this reason, the European Union Habitat Directive included them among priority habitats to be preserved. Although their ecological role is well established, connectivity pat‐ terns are still poorly investigated, representing a limit in conservation planning. The present study pioneers a novel approach for the analysis of connectivity in marine bioconstructor species, which often lack suitable genetic markers, by taking advantage of next‐generation sequencing techniques. We assess the geographical patterns of genomic variation of the sunset cup coral Leptopsammia pruvoti Lacaze‐Duthiers, 1897, an ahermatypic, non‐zooxanthellate and solitary scleractinian coral species common in coralligenous habitats and distributed across the Mediterranean Sea. Location: The Italian coastline (Western and Central Mediterranean). Methods: We applied the restriction site‐associated 2b‐RAD approach to genotype over 1,000 high‐quality and filtered single nucleotide polymorphisms in 10 population samples. Results: The results revealed the existence of a strongly supported genetic structure, with highly significant pairwise FST values between all the population samples, includ‐ ing those collected about 5 km apart from each other. Moreover, genomic data indi‐ cate that the strongest barriers to gene flow are between the western (Ligurian–Tyrrhenian Sea) and the eastern side (Adriatic Sea) of the Italian peninsula. Main conclusions: The strong differentiation found in L. pruvoti is similar to that found in other species of marine bioconstructors investigated in this area, but it strongly contrasts with the small differences found in many fish and invertebrates at the same geographical scale. All in one, our results highlight the importance of assessing con‐ nectivity in species belonging to coralligenous habitats as, due to their limited disper‐ sal ability, they might require specific spatial conservation measures.