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To better predict population evolution of invasive species in introduced areas it is critical to identify and understand the mechanisms driving genetic diversity and structure in their native range. Here, we combined analyses of the mitochondrial COI gene and 11 microsatellite markers to investigate both past demographic history and contemporaneous genetic structure in the native area of the gastropod Tritia neritea, using Bayesian skyline plots (BSP), multivariate analyses and Bayesian clustering. The BSP framework revealed population expansions, dated after the last glacial maximum. The haplotype network revealed a strong geographic clustering. Multivariate analyses and Bayesian clustering highlighted the strong genetic structure at all scales, between the Black Sea and the Adriatic Sea, but also within basins. Within basins, a random pattern of genetic patchiness was observed, suggesting a superimposition of processes involving natural biological effects (no larval phase and thus limited larval dispersal) and putative anthropogenic transport of specimens. Contrary to the introduced area, no isolation-by-distance patterns were recovered in the Mediterranean or the Black Seas, highlighting different mechanisms at play on both native and introduced areas, triggering unknown consequences for species’ evolutionary trajectories. These results of Tritia neritea populations on its native range highlight a mixture of ancient and recent processes, with the effects of paleoclimates and life history traits likely tangled with the effects of human-mediated dispersal.

Aim: To infer cold-water corals’ (CWC) post-glacial phylogeography and assess the role of Mediterranean Sea glacial refugia as origins for the recolonization of the northeastern Atlantic Ocean. Location: Northeastern Atlantic Ocean and Mediterranean Sea. Taxon: Lophelia pertusa, Madrepora oculata. Methods: We sampled CWC using remotely operated vehicles and one sediment core for coral and sediment dating. We characterized spatial genetic patterns (microsatellites and a nuclear gene fragment) using networks, clustering and measures of genetic differentiation. Results: Inferences from microsatellite and sequence data were congruent, and showed a contrast between the two CWC species. Populations of L. pertusa present a dominant pioneer haplotype, local haplotype radiations and a majority of endemic variation in lower latitudes. Madrepora oculata populations are differentiated across the northeastern Atlantic and genetic lineages are poorly admixed even among neighbouring sites. Conclusions: Our study shows contrasting post-glacial colonization pathways for two key habitat-forming species in the deep sea. The CWC L. pertusa has likely undertaken a long-range (post-glacial) recolonization of the northeastern Atlantic directly from refugia located along southern Europe (Mediterranean Sea or Gulf of Cadiz). In contrast, the stronger genetic differentiation of M. oculata populations mirrors the effects of long-term isolation in multiple refugia. We suggest that the distinct and genetically divergent, refugial populations initiated the post-glacial recolonization of the northeastern Atlantic margins, leading to a secondary contact in the northern range and reaching higher latitudes much later, in the late Holocene. This study highlights the need to disentangle the influences of present-day dispersal and evolutionary processes on the distribution of genetic polymorphisms, to unravel the influence of past and future environmental changes on the co

The deep southern Adriatic Sea is home of widespread cold-water coral colonization (Madrepora oculata, Lophelia pertusa, Desmophyllum dianthus) which is at present limited by large to its western (Apulian) margin and central part, including the Bari Canyon system. On the contrary, the eastern side is today almost deprived of significant coral growth and this asymmetrical distribution has been ascribed primarily to the action of the North Adriatic Dense Water (NAdDW) that impinges more efficiently on the Apulian margin. The collection of subfossil specimens of M. oculata, L. pertusa and D. dianthus provided the very first dates for cold-water coral colonization along the eastern margin. Once combined with known distribution of live cold-water corals and fossil occurrences in the southern Adriatic Sea, uranium-series dating provides evidence of (i) coral presence in the southeastern Adriatic during the Last Glacial Maximum (LGM), followed by (ii) a time of basin-wide colonization after the post-Last Glacial Maximum and encompassing the Younger Dryas, (iii) another time of undocumented coral presence with the onset of Sapropel S1. Perturbations of the thermohaline circulation in this sector of the Mediterranean basin might have governed the presence and demise of the resident cold-water coral populations interfering with strength and trajectories of main water masses. It is hypothesized that the achievement of the current asymmetrical distribution did occur since the end of S1 protracting to present time. The post-S1 reorganization likely brought to the current hydrological situation where the influence of NAdDW prevails in the western side and corals are doing at best on its trajectory. The scarcity of datable material makes the proposed scenario open to debate and in need of further supporting evidence.

In this work, we present preliminary results of the first application in the Mediterranean Sea of a hyperspectral camera, a device commonly used for satellite or airborne remote sensing, adapted for the underwater environment. The spectral analysis was carried out on hyperspectral images acquired in two different environmental settings in the southern Adriatic Sea. This new technology shows high potentialities of application for benthic habitat mapping and monitoring.

Investigation of sea-level positions during the highly-dynamic Marine Isotope Stage 3 (MIS 3: 29–61 kyrs BP) proves difficult because: (i) in stable and subsiding areas, coeval coastal sediments are currently submerged at depths of few to several tens of meters below the present sea level; (ii) in uplifting areas, the preservation of geomorphic features and sedimentary records is limited due to the erosion occurred during the Last Glacial Maximum (LGM) with sea level at a depth of −130 m, followed by marine transgression that determined the development of ravinement surfaces. This study discusses previous research in the Mediterranean and elsewhere, and describes new fossiliferous marine deposits overlaying the metamorphic bedrock at Cannitello (Calabria, Italy). Radiocarbon ages of marine shells (about 43 kyrs cal BP) indicate that these deposits, presently between 28 and 30 m above sea level, formed during MIS 3.1. Elevation correction of the Cannitello outcrops (considered in an intermediate-to-far-field position with respect to the ice sheet) with the local vertical tectonic rate and Glacial Isostatic Adjustment (GIA) rate allows the proposal of a revision of the eustatic depth for this highstand. Our results are consistent with recently proposed estimates based on a novel ice sheet modelling technique.