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Detecting and responding to threat engages several neural nodes including the amygdala, hippocampus, insular cortex, and medial prefrontal cortices. Recent propositions call for the integration of more distributed neural nodes that process sensory and cognitive facets related to threat. Integrative, sensitive, and reproducible distributed neural decoders for the detection and response to threat and safety have yet to be established. We combine functional MRI data across varying threat conditioning and negative affect paradigms from 1465 participants with multivariate pattern analysis to investigate distributed neural representations of threat and safety. The trained decoders sensitively and specifically distinguish between threat and safety cues across multiple datasets. We further show that many neural nodes dynamically shift representations between threat and safety. Our results establish reproducible decoders that integrate neural circuits, merging the well-characterized ‘threat circuit’ with sensory and cognitive nodes, discriminating threat from safety regardless of experimental designs or data acquisition parameters.

Paramuricea clavata is an ecosystem architect of the Mediterranean temperate reefs that is currently threatened by episodic mass mortality events related to global warming. The microbiome may play an active role in the thermal stress susceptibility of corals, potentially holding the answer as to why corals show differential sensitivity to heat stress. To investigate this, the prokaryotic and eukaryotic microbiome of P. clavata collected from around the Mediterranean was characterised before experimental heat stress to determine if its microbial composition influences the thermal response of the holobiont. We found that members of P. clavata's microeukaryotic community were significantly correlated with thermal stress sensitivity. Syndiniales from the Dino-Group I Clade 1 were significantly enriched in thermally resistant corals, while the apicomplexan corallicolids were significantly enriched in thermally susceptible corals. We hypothesise that P. clavata mortality following heat stress may be caused by a shift from apparent commensalism to parasitism in the corallicolid-coral host relationship driven by the added stress. Our results show the potential importance of corallicolids and the rest of the microeukaryotic community of corals to understanding thermal stress response in corals and provide a useful tool to guide conservation efforts and future research into coral-associated microeukaryotes

This dataset compiles data on geographic and depth distribution, demography, population and mortality, of different habitat-forming invertebrate species dwelling the Mediterranean coralligenous assemblages

Aim: Intraspecific genetic diversity is one of the pillars of biodiversity, supporting the resilience and evolutionary potential of populations. Yet, our knowledge regarding the patterns of genetic diversity at macroecological scales, so-called macrogenetic patterns, remains scarce, particularly in marine species. Marine habitat-forming (MHF) species are key species in some of the most diverse but also most impacted marine ecosystems, such as coral reefs and marine forests. We characterize the patterns and drivers of genetic diversity in MHF species and provide a macrogenetic baseline, which can be used for conservation planning and for future genetic monitoring programmes. Location: Global. Time period: Contemporary. Major taxa studied: Bryozoans, hexacorals, hydrozoans, octocorals, seagrasses, seaweeds, sponges. Methods: We analysed a database including genetic diversity estimates based on microsatellites in more than 9,000 georeferenced populations from 140 species, which belong to seven animal and plant taxa. Focusing on expected heterozygosity, we used generalized additive models to test the effect of latitude, taxon, and conservation status. We tested the correlation between the species richness and the genetic diversity. Results: We reveal a significant but complex biogeographic pattern characterized by a bimodal latitudinal trend influenced by taxonomy. We also report a positive species genetic diversity correlation at the scale of the ecoregions. The difference in genetic diversity between protected and unprotected areas was not significant. Main conclusions: The contrasting results between MHF animals and plants suggest that the latitudinal genetic diversity patterns observed in MHF species are idiosyncratic, as reported in terrestrial species. Our results support the existence of shared drivers between genetic and species diversities, which remain to be formally identified. Concerning, these macrogenetic patterns are not aligned from the existing network

The accurate delimitation of species boundaries in nonbilaterian marine taxa is notoriously difficult, with consequences for many studies in ecology and evolution. Anthozoans are a diverse group of key structural organisms worldwide, but the lack of reliable morphological characters and informative genetic markers hampers our ability to understand species diversification. We investigated population differentiation and species limits in Atlantic (Iberian Peninsula) and Mediterranean lineages of the octocoral genus Paramuricea previously identified as P. clavata. We used a diverse set of molecular markers (microsatellites, RNA-seq derived single-copy orthologues [SCO] and mt-mutS [mitochondrial barcode]) at 49 locations. Clear segregation of Atlantic and Mediterranean lineages was found with all markers. Species-tree estimations based on SCO strongly supported these two clades as distinct, recently diverged sister species with incomplete lineage sorting, P. cf. grayi and P. clavata, respectively. Furthermore, a second putative (or ongoing) speciation event was detected in the Atlantic between two P. cf. grayi color morphotypes (yellow and purple) using SCO and supported by microsatellites. While segregating P. cf. grayi lineages showed considerable geographic structure, dominating circalittoral communities in southern (yellow) and western (purple) Portugal, their occurrence in sympatry at some localities suggests a degree of reproductive isolation. Overall, our results show that previous molecular and morphological studies have underestimated species diversity in Paramuricea occurring in the Iberian Peninsula, which has important implications for conservation planning. Finally, our findings validate the usefulness of phylotranscriptomics for resolving evolutionary relationships in octocorals

Recurrent mass mortality events (MMEs) linked to marine heatwaves (MHWs) have been affecting Mediterranean coralligenous habitats. Combining field surveys with experiments in controlled conditions allowed to characterize spatial variability in responses to thermal stress among species, populations and individuals. However, the temporal variability in this response remains poorly known. Thus, we replicated common garden experiments (control vs. thermal stress) during three consecutive years (2015-2017) using the same individuals from three populations of the habitat-forming octocoral Paramuricea clavata. We found that the average percentage of tissue necrosis per population during the experiment significantly variated across years. This result was due to the decrease in the probability of survival in 2017 when a severe MHWs was observed in the study area. Furthermore, we genotyped all individuals with 14 microsatellites to define the genetic framework of the study and found that populations were genetically differentiated, but their respective levels of genetic isolation were similar and not related to mean tissue necrosis. At individual level, we tested for the occurrence of heterosis. Overall, our data characterize in detail the temporal variability in the response to thermal stress showing that this response may: i) critically driven by summer conditions and ii) under stronger influence of environmental factors compared to genetics. These results unambiguously question the potential adaptation of P. clavata to on-going warming trend

Current efforts to halt the decline of biodiversity are based primarily on protecting species richness. This narrow focus overlooks key components of biological diversity, particularly the infra-species genetic diversity, which is critical to consider with respect to genetic adaptation in changing environments. While comparative population genetics is recognized as a relevant approach to improve biodiversity management, it is still barely considered in practice. Here, a comparative population genetics study was conducted on two key habitat-forming octocoral species, Corallium rubrum and Paramuricea clavata, to contribute to management of two Marine Protected Areas (MPAs) in the northwestern Mediterranean. Contrasting patterns of genetic diversity and structure were observed in the two species, although they share many common biological features and live in similar habitats. Differential genetic drift effects induced by species-specific reproductive strategies and demographic histories most likely explain these differences. The translation of our results into management strategies supports the definition of four management units. We identified a coldspot of genetic diversity, with genetically isolated populations, and a hotspot of genetic diversity that has a central role in the system’s connectivity. Interestingly, they corresponded to the most recent and the oldest protected areas, respectively. This case study shows how moving from a “species pattern” perspective to an “eco-evolutionary processes” perspective can help assess and contribute to the effectiveness of biodiversity management plans.

How historical and contemporary evolutionary processes shape the patterns of genetic diversity and differentiation across species’ distribution range remains an open question with strong conservation implications. Negative gradients of neutral genetic diversity from central to peripheral populations were reported in various species, yet, the underlying processes are still a matter of debate. Two non-mutually exclusive hypotheses involving contemporary vs. historical processes are usually considered to explain these negative gradients. Following the “central-peripheral hypothesis”, the genetic diversity should decline from the centre toward the peripheries of a species’ range in response to demo-genetic stochasticity linked to the environmental characteristics of peripheral habitats. On the other hand, the “postglacial range expansion hypothesis” suggests that historical processes such as serial founder events recolonization following the Last Glacial Maximum (LGM 24-18,000 years ago), shape negative genetic gradients from the source to the edge of the expansion range. Focusing on the Mediterranean orange stony coral, Astroides calycularis, we tested these hypotheses. Standing on microsatellite genotyping data from 29 populations distributed across its distribution range, we i) characterized the pattern of neutral genetic diversity; ii) gave insights into the underlying processes; and iii) discussed conservation implications, with emphasis on the Zembra national park (Tunisia). We show that the decrease of genetic diversity (He, Ar(g)) and an increase of genetic differentiation (population-specific FST) from the Centre to the Eastern and Western Peripheries of the distribution range is most likely explained by “the postglacial range expansion hypothesis” rather than the “central-peripheral hypothesis”. The populations from Zembra National Park show the highest genetic diversity reported so far in the species. We argue that enforcement of conservation measures should

Recurrent mass mortality events (MMEs) linked to marine heatwaves (MHWs) have been observed in the Mediterranean Sea affecting thousands of kilometers of coastline. Coralligenous habitats were among the most impacted during these events. Information on how the exposure to recurrent MHWs is affecting the coralligenous is critical to anticipate the consequences of climate change and implement actions to enhance their resilience. Combining field surveys with experiments in controlled conditions allowed to dilucidate the differential responses to thermal stress among species, populations and individuals and to explore the spatial and taxonomic variability response to thermal stress linked to MHWs. Yet, the temporal variability in the response to thermal stress remains to be characterized. Thus, we aim to fill this gap focusing on the temporal variability in the response to thermal stress of the coralligenous key habitat-forming species Paramuricea clavata (Plexauridae). We replicated thermal stress experiments during 3 consecutive years following a common garden setup (control vs. thermal stress) involving the same individuals from the same three populations. Considering different phenotypic responses including the level of tissue necrosis during the time of the experiment and the survival of the individuals, we found that the average percentage of tissue necrosis per population variated greatly across years while the probability of survival was considerably reduced in 2017. During the experiments, several individuals from the 3 populations systematically showed reduced level of tissue necrosis suggesting resistance to thermal stress. Overall our data will contribute to help better inform further conservation strategies of habitat-forming coral species in the Mediterranean Sea

Understanding the factors and processes that shape intra-specific sensitivity to heat stress is fundamental to better predicting the vulnerability of benthic species to climate change. Here, we investigate the response of a habitat-forming Mediterranean octocoral, the red gorgonian Paramuricea clavata (Risso, 1826) to thermal stress at multiple biological and geographical scales. Samples from eleven P. clavata populations inhabiting four localities separated by hundreds to more than 1500 km of coast and with contrasting thermal histories were exposed to a critical temperature threshold (25 °C) in a common garden experiment in aquaria. Ten of the 11 populations lacked thermotolerance to the experimental conditions provided (25 days at 25 °C), with 100% or almost 100% colony mortality by the end of the experiment. Furthermore, we found no significant association between local average thermal regimes nor recent thermal history (i.e., local water temperatures in the 3 months prior to the experiment) and population thermotolerance. Overall, our results suggest that local adaptation and/or acclimation to warmer conditions have a limited role in the response of P. clavata to thermal stress. The study also confirms the sensitivity of this species to warm temperatures across its distributional range and questions its adaptive capacity under ocean warming conditions. However, important inter-individual variation in thermotolerance was found within populations, particularly those exposed to the most severe prior marine heatwaves. These observations suggest that P. clavata could harbor adaptive potential to future warming acting on standing genetic variation (i.e., divergent selection) and/or environmentally-induced phenotypic variation (i.e., intra- and/or intergenerational plasticity)

The Gray’s sea fan, Paramuricea grayi (Johnson, 1861), typically inhabits deep littoral and circalittoral habitats of the eastern temperate and tropical Atlantic Ocean. Along the Iberian Peninsula, where P. grayi is a dominant constituent of circalittoral coral gardens, two segregating lineages (yellow and purple morphotypes) were recently identified using single-copy nuclear orthologues. The mitochondrial genomes of 9 P. grayi individuals covering both color morphotypes were assembled from RNA-seq data, using samples collected at three sites in southern (Sagres and Tavira) and western (Cape Espichel) Portugal. The complete circular mitogenome is 18,668 bp in length, has an A + T-rich base composition (62.5%) and contains the 17 genes typically found in Octocorallia: 14 protein-coding genes (atp6, atp8, cob, cox1-3, mt-mutS, nad1-6, and nad4L), the small and large subunit rRNAs (rns and rnl), and one transfer RNA (trnM). The mitogenomes were nearly identical for all specimens, though we identified a noteworthy polymorphism (two SNPs 9 bp apart) in the mt-mutS of one purple individual that is shared with the sister species P. clavata. The mitogenomes of the two species have a pairwise sequence identity of 99.0%, with nad6 and mt-mutS having the highest rates of non-synonymous substitutions

Climate change is causing an increase in the frequency and intensity of marine heatwaves (MHWs) and mass mortality events (MMEs) of marine organisms are one of their main ecological impacts. Here, we show that during the 2015–2019 period, the Mediterranean Sea has experienced exceptional thermal conditions resulting in the onset of five consecutive years of widespread MMEs across the basin. These MMEs affected thousands of kilometers of coastline from the surface to 45 m, across a range of marine habitats and taxa (50 taxa across 8 phyla). Significant relationships were found between the incidence of MMEs and the heat exposure associated with MHWs observed both at the surface and across depths. Our findings reveal that the Mediterranean Sea is experiencing an acceleration of the ecological impacts of MHWs which poses an unprecedented threat to its ecosystems' health and functioning. Overall, we show that increasing the resolution of empirical observation is critical to enhancing our ability to more effectively understand and manage the consequences of climate change.

Quantifying changes in functional community structure driven by disturbance is critical to anticipate potential shifts in ecosystem functioning. However, how marine heatwaves (MHWs) affect the functional structure of temperate coral‐dominated communities is poorly understood. Here, we used five long‐term (> 10 years) records of Mediterranean coralligenous assemblages in a multi‐taxa, trait‐based analysis to investigate MHW‐driven changes in functional structure. We show that, despite stability in functional richness (i.e. the range of species functional traits), MHW‐impacted assemblages experienced long‐term directional changes in functional identity (i.e. their dominant trait values). Declining traits included large sizes, long lifespans, arborescent morphologies, filter‐feeding strategies or calcified skeletons. These traits, which were mostly supported by few sensitive and irreplaceable species from a single functional group (habitat‐forming octocorals), disproportionally influence certain ecosystem functions (e.g. 3D‐habitat provision). Hence, MHWs are leading to assemblages that are deficient in key functional traits, with likely consequences for the ecosystem functioning

Marine animal forests are benthic communities dominated by sessile suspension feeders (such as sponges, corals, and bivalves) able to generate three-dimensional (3D) frameworks with high structural complexity. The biodiversity and functioning of marine animal forests are strictly related to their 3D complexity. The present paper aims at providing new perspectives in underwater optical surveys. Starting from the current gaps in data collection and analysis that critically limit the study and conservation of marine animal forests, we discuss the main technological and methodological needs for the investigation of their 3D structural complexity at different spatial and temporal scales. Despite recent technological advances, it seems that several issues in data acquisition and processing need to be solved, to properly map the different benthic habitats in which marine animal forests are present, their health status and to measure structural complexity. Proper precision and accuracy should be chosen and assured in relation to the biological and ecological processes investigated. Besides, standardized methods and protocols are strictly necessary to meet the FAIR (findability, accessibility, interoperability, and reusability) data principles for the stewardship of habitat mapping and biodiversity, biomass, and growth data

Understanding the resilience of temperate reefs to climate change requires exploring the recovery capacity of their habitat-forming species from recurrent marine heatwaves (MHWs). Here, we show that, in a Mediterranean highly enforced marine protected area established more than 40 years ago, habitat-forming octocoral populations that were first affected by a severe MHW in 2003 have not recovered after 15 years. Contrarily, they have followed collapse trajectories that have brought them to the brink of local ecological extinction. Since 2003, impacted populations of the red gorgonian Paramuricea clavata (Risso, 1826) and the red coral Corallium rubrum (Linnaeus, 1758) have followed different trends in terms of size structure, but a similar progressive reduction in density and biomass. Concurrently, recurrent MHWs were observed in the area during the 2003–2018 study period, which may have hindered populations recovery. The studied octocorals play a unique habitat-forming role in the coralligenous assemblages (i.e. reefs endemic to the Mediterranean Sea home to approximately 10% of its species). Therefore, our results underpin the great risk that recurrent MHWs pose for the long-term integrity and functioning of these emblematic temperate reefs

Aim: How historical and contemporary eco-evolutionary processes shape the patterns of genetic diversity and differentiation across species’ distribution range remains an open question with strong conservation implications. Focusing on the orange stony coral, Astroides calycularis, we (a) characterized the pattern of neutral genetic diversity across the distribution range; (b) gave insights into the underlying processes; and (c) discussed conservation implications with emphasis on a national park located on a hotspot of genetic diversity. Location: South Mediterranean Sea and Zembra National Park. Methods: We combined new data from 12 microsatellites in 13 populations located in the Centre and in the Western Periphery of the distribution range with a published dataset including 16 populations from the Western and Eastern Peripheries. We analysed the relationship among parameters of genetic diversity (He, Ar(g)) and structure (population-specific FST) and two measures of geographic peripherality. We compared two estimators of pairwise genetic structure (GST, DEST) across the distribution range. The evolutionary and demographic history of the populations following the Last Glacial Maximum was reconstructed using approximate Bayesian computations and maximum-likelihood analyses. We inferred the contemporary connectivity among populations from Zembra National Park and with the neighbouring area of Cap Bon. Results: We demonstrate a decrease in genetic diversity and an increase in genetic differentiation from the Centre to the Eastern and Western Peripheries of the distribution range. Populations from Zembra show the highest genetic diversity reported in the species. We identified a spillover effect towards Cap Bon. Main conclusions: The patterns of genetic diversity and differentiation are most likely explained by “the postglacial range expansion hypothesis” rather than the “central–peripheral hypothesis.” Enforcement of conservation measures should be considered to prot

Restoration is considered an effective strategy to accelerate the recovery of biological communities at local scale. However, the effects of restoration actions in the marine ecosystems are still unpredictable. We performed a global analysis of published literature to identify the factors increasing the probability of restoration success in coastal and marine systems. Our results confirm that the majority of active restoration initiatives are still concentrated in the northern hemisphere and that most of information gathered from restoration efforts derives from a relatively small subset of species. The analysis also indicates that many studies are still experimental in nature, covering small spatial and temporal scales. Despite the limits of assessing restoration effectiveness in absence of a standardized definition of success, the context (degree of human impact, ecosystem type, habitat) of where the restoration activity is undertaken is of greater relevance to a successful outcome than how (method) the restoration is carried out. Contrary to expectations, we found that restoration is not necessarily more successful closer to protected areas (PA) and in areas of moderate human impact. This result can be motivated by the limits in assessing the success of interventions and by the tendency of selecting areas in more obvious need of restoration, where the potential of actively restoring a degraded site is more evident. Restoration sites prioritization considering human uses and conservation status present in the region is of vital importance to obtain the intended outcomes and galvanize further actions.

The white gorgonian, Eunicella singularis, is thriving in Mediterranean hard-bottom communities; however, data regarding its distribution and ecology remain absent and insufficient, particularly in the southern Mediterranean Sea. In this study, the population structure and disturbance levels of the most common gorgonian in Tunisia were assessed for the first time. During two years (2015-2016), a total of 818 colonies of E. singularis were surveyed in five coastal sites, by scuba diving, between 7 to 40 m depth. Collected data included density, colony height, and extent of injury. Mean population density was 11.91 ± 7.42 colonies per m2 (mean ± SD). Mean and maximum colony heights were 16.49 ± 5.59 cm and 51 cm, respectively. Among populations, mean extent of tissue injury differed considerably, ranging from 12.47% to 58.88% and most affected colonies showed old necrosis. These data regarding the demographic structure and level of injuries are needed to provide insights into the conservation status of the Tunisian population of E. singularis. Indeed, data on the amount of necrosis could highlight the strength of the colonies’ exposure to mechanical impacts and are consequently crucial to study changes in their demographic structure over time. In fact, the size, structures, and the high level of tissue necrosis of the colonies suggest a low conservation status of the studied Tunisian populations

Marine protected areas (MPAs) are one of the most efficient conservation tools to buffer marine biodiversity loss induced by human activities. Beside effective enforcement, an accurate understanding of the eco-evolutionary processes underlying the patterns of biodiversity is needed to reap the benefits of management policies. In this context, integrating population genetics with demographic data, the demo-genetic approach, is particularly relevant to shift from a “species-based pattern” toward an “eco-evolutionary-based processes” conservation. Here, targeting a key species in the Mediterranean coralligenous, the red coral, Corallium rubrum, in an emblematic Mediterranean MPA, the “Réserve Naturelle de Scandola” (France), we applied demo-genetic approaches at two contrasted spatial scales, among populations and within one population, to (i) infer the demographic connectivity among populations in the metapopulation network and (ii) shed new light on the genetic connectivity and on the demographic transitions underlying the dynamics of a near-pristine population. Integrating different spatial and temporal scales, we demonstrated (i) an apparent temporal stability in the pattern of genetic diversity and structure in the MPA in spite of a dramatic demographic decline and (ii) contrasted levels of genetic isolation but substantial demographic connectivity among populations. Focusing on the near-pristine population, we complemented the characterization of red coral demographic connectivity suggesting (iii) temporal variability and (iv) the occurrence of collective dispersal. In addition, we demonstrated (v) contrasted patterns of spatial genetic structure (SGS), depending on the considered stage-class (adults vs. juveniles), in the near-pristine population. This last result points out that the overall SGS resulted from a restricted dispersal of locally produced juveniles (SGS among adults and juveniles) combined to mortality during early life stages (decrease of SGS from

Mediterranean gorgonians are foundation species that support the high diversity associated with Mediterranean coralligenous assemblages. Through the formation of 3D structures, they provide structural complexity and thereby habitat and refugia to numerous associated species, among other ecological benefits. However, these organisms are especially vulnerable to the increasingly frequent and intense marine heatwaves (MHWs). In recent decades, MHWs deeply impacted octocoral species such as the red coral Corallium rubrum and the red gorgonian Paramuricea clavata across large geographical scales, leading to mass mortality events (MMEs). Although the MME immediate and mid-term (3-4 years) effects on the population dynamics of these species are well documented, a long-term evaluation of the impacted populations trajectories is still lacking. This hinders our understanding of the recovery capacity of these key species, and thus ofthe potential delayed effects that MMEs could have on their associated communities. In this study, we performed a long-term status assessment of different populations of P. clavata and C. rubrum that were affected by the MME occurred in the summer of 2003in Scandola Marine Protected Area (MPA), Corsica. Our results show that since 2003, impacted populations have followed different trajectories in terms of density, size structure or tissue necrosis, but a general progressive reduction in biomass. This indicates that the affected populations have no recovered over almost two decades, despite the high protection regime existing in the MPA. Furthermore, many populations followed collapse trajectories that have brought them to the brink of ecological extinction, probably due to the MHW recurrence observed since 2003. Since Mediterranean octocorals play a unique role on the functioning of coralligenous assemblages, the long-term delayed effects of the MME observed in our study underpins the relevant role that stochastic climatic events can play not only

Climate change is one of the major current drivers of disturbance in marine coastal ecosystems. To date, Marine Protected Areas (MPAs) are the most effective tool for marine conservation. However, their efficacy in adapting and mitigating the effects of climate change remains controversial. We conducted a comprehensive literature review of climate change effects and MPAs for the last fifteen years (2005-2019). We restricted our review to benthic species living in temperate rocky habitats, which are hotspots of biodiversity worldwide and are being affected by climate change. The number of papers addressing MPAs and climate change has increased steadily over the past decade. The majority of studies (63%) have been carried out on the west coast of the USA, the Mediterranean and the Australian coast, which comprises only 23 of the 79 temperate ecoregions. In 32% of these ecoregions no work was found. Overall, our results show that evidence is lacking to conclude that MPAs promote a greater resistance and a faster recovery of marine ecosystems, that is, their resilience. To date, just a few articles consider this question, and of those only about half consider that reserves play an important role in adapting and/or mitigating the effects derived from climate crisis. Therefore, we conclude that that sound empirical studies specifically designed to test to what extent MPAs are supporting the resilience of ecosystems the face of climate change are urgently needed to support effective biodiversity conservation

The octocoral, Paramuricea clavata, is a habitat-forming anthozoan with a key ecological role in rocky benthic and biodiversity-rich communities in the Mediterranean and Eastern Atlantic. Shallow populations of P. clavata in the North-Western Mediterranean are severely affected by warming-induced mass mortality events (MMEs). These MMEs have differentially impacted individuals and populations of P. clavata (i.e., varied levels of tissue necrosis and mortality rates) over thousands of kilometers of coastal areas. The eco-evolutionary processes, including genetic factors, contributing to these differential responses remain to be characterized. Here, we sequenced a P. clavata individual with short and long read technologies, producing 169.98 Gb of Illumina paired-end and 3.55 Gb of Oxford Nanopore Technologies (ONT) reads. We obtained a de novo genome assembly accounting for 607 Mb in 64,145 scaffolds. The contig and scaffold N50s are 19.15 Kb and 23.92 Kb, respectively. Despite of the low contiguity of the assembly, its gene completeness is relatively high, including 75.8% complete and 9.4% fragmented genes out of the 978 metazoan genes contained in the metazoa_odb9 database. A total of 62,652 protein-coding genes have been annotated. This assembly is one of the few octocoral genomes currently available. This is undoubtedly a valuable resource for characterizing the genetic bases of the differential responses to thermal stress and for the identification of thermo-resistant individuals and populations. Overall, having the genome of P. clavata will facilitate studies of various aspects of its evolutionary ecology and elaboration of effective conservation plans such as active restoration to overcome the threats of global change

Understanding the interactions among demographic parameters, mating system and population dynamics is key to predict the response of populations to global change. The Mediterranean red coral is a precious octocoral suffering from population decline due to overfishing and warming-driven mass mortality events. While the demographic consequences of these two pressures are well characterized, little is known regarding their impact on population dynamics and evolution of red coral populations. The main objective of this study was to fill this gap focusing more particularly on mating pattern and genetic drift. Combining sibship and progeny arrays analyses, a genetic characterization of the red coral mating system was conducted. In addition, a synchronic approach was developed comparing mating patterns in two populations with contrasting demographic patterns: a pristine-like population and a declining population. The results show that polyandry is likely to be the norm in red coral. The similar patterns of genetic diversity between adults and larvae combined with the lack of differential reproductive success among putative fathers did not support significant sweepstakes effects during larval production. While instantaneous biparental inbreeding was detected, no long-term inbreeding was observed even in the declining population. Mating patterns and effective population sizes in the two populations were not statistically different. Nevertheless, a trend towards a slightly higher inbreeding and a lower number of breeders was observed in the declining population. Accordingly, we hypothesized that an increase in male gamete dispersal may buffer the increase of genetic drift expected in the declining population. This feedback between demographic decline and reproductive pattern may potentially take part in the long-term persistence of red coral populations. However, the negative trend reported in the declining population unambiguously supports the need to maintain high densities

Marine ecosystems are strongly impacted by the consequences of human activities, such as habitat destruction or artificialization and climate change. In the Mediterranean Sea, sessile benthic species, and particularly octocorals, have been affected by mass mortality events linked with positive thermal anomalies. The future survival of octocoral populations impacted by 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 (seven for P. clavata, five for E. cavolini), we analyzed the genetic diversity of populations on artificial substrates and their differentiation from other neighboring populations. For P. clavata the populations on artificial substrates were not or lowly differentiated from the closest populations (1.3–1.6 km) on natural substrates, and showed 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 or relatedness following recuperation after mortality events. In both cases, our results suggest the input from different populations in the recolonization process, which helps in maintaining the genetic diversity. These results are useful for the management of these species and of associated ecosystems