87 research outputs found

    Not out of the Mediterranean: Atlantic populations of the gorgonian Paramuricea clavata are a separate sister species under further lineage diversification

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    International audienceThe 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 ou

    On the specific status of eastern Mediterranean Dendrophyllia corals (Cnidaria, Anthozoa): Genetic characterization and speciation scenarios

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    International audienceThe deep鈥恠ea corals Dendrophyllia ramea and Dendrophyllia cornigera occur in Mediterranean and Atlantic waters. Both species are found in different environmental conditions, and they can colonize hard and soft substrates. These species then display an important ecological plasticity along with morphological plasticity. Nevertheless, there is a large knowledge gap on the genetic characteristics of the two species, including on the relationships between them and the possibility of cryptic species along their range. The recent discovery of Dendrophyllia populations off Cyprus in the eastern Mediterranean Sea raised new questions in this context. These corals were related to D.鈥塺amea but had some morphological differences with other known populations of this species. Here, we study the specific status of Dendrophyllia corals from Cyprus on the basis of morphology and genetics. The genetic data are interpreted by comparison with the same analysis performed on two Caryophyllia species. Both morphological and genetic data confirm that corals found off Cyprus belong to the D.鈥塺amea species. We further tested the speciation scenario using transcriptome data: the results indicate an absence of current gene flow between D.鈥塺amea and D.鈥塩ornigera and that the divergence occurred more than 3鈥塵illion years ago. We discuss the possible historical and ecological factors which may have shaped speciation in these species

    Not out of the Mediterranean: Atlantic populations of the gorgonian Paramuricea clavata are a separate sister species under further lineage diversification

    No full text
    International audienceThe 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 ou

    Not out of the Mediterranean: Atlantic populations of the gorgonian Paramuricea clavata are a separate sister species under further lineage diversification

    No full text
    International audienceThe 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 ou

    Temporal genomics help in deciphering neutral and adaptive patterns in the contemporary evolution of kelp populations

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    ABSTRACT The long-term persistence of species in the face of climate change can be evaluated by examining the interplay between selection and genetic drift in the contemporary evolution of populations. In this study, we focused on spatial and temporal genetic variation in four populations of the cold-water kelp Laminaria digitata using thousands of SNPs (ddRAD-seq). These populations were sampled from the center to the south margin in the North Atlantic at two different time points, spanning at least two generations. By conducting genome scans for local adaptation from a single time point, we successfully identified candidate loci that exhibited clinal variation, closely aligned with the latitudinal changes in temperature. This finding suggests that temperature may drive the adaptive response of kelp populations, although other factors, such as the species鈥 demographic history should be considered. Furthermore, we provided compelling evidence of positive selection through the examination of allele frequency changes over time, offering additional insights into the impact of genetic drift. Specifically, we detected candidate loci exhibiting temporal differentiation that surpassed the levels typically attributed to genetic drift at the south margin, confirmed through simulations. This finding was in sharp contrast with the lack of detection of outlier loci based on temporal differentiation in a population from the North Sea, exhibiting low levels of genetic diversity, that further decreased over time. These contrasting evolutionary scenarios among populations can be primarily attributed to the differential prevalence of selection relative to genetic drift. In conclusion, our study highlights the potential of temporal genomics to gain deeper insights into the contemporary evolution of marine foundation species in response to rapid environmental changes

    From genomics to integrative species delimitation? The case study of the Indo-Pacific Pocillopora corals

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    With the advent of genomics, sequencing thousands of loci from hundreds of individuals now appears feasible at reasonable costs, allowing complex phylogenies to be resolved. This is particularly relevant for cnidarians, for which insufficient data is available due to the small number of currently available markers and obscures species boundaries. Difficulties in inferring gene trees and morphological incongruences further blur the study and conservation of these organisms. Yet, can genomics alone be used to delimit species? Here, focusing on the coral genus Pocillopora, whose colonies play key roles in Indo-Pacific reef ecosystems but have challenged taxonomists for decades, we explored and discussed the usefulness of multiple criteria (genetics, morphology, biogeography and symbiosis ecology) to delimit species of this genus. Phylogenetic inferences, clustering approaches and species delimitation methods based on genome-wide single-nucleotide polymorphisms (SNP) were first used to resolve Pocillopora phylogeny and propose genomic species hypotheses from 356 colonies sampled across the Indo-Pacific (western Indian Ocean, tropical southwestern Paci铿乧 and south-east Polynesia). These species hypotheses were then compared to other lines of evidence based on genetic, morphology, biogeography and symbiont associations. Out of 21 species hypotheses delimited by genomics, 13 were strongly supported by all approaches, while six could represent either undescribed species or nominal species that have been synonymised incorrectly. Altogether, our results support (1) the obsolescence of macromorphology (i.e., overall colony and branches shape) but the relevance of micromorphology (i.e., corallite structures) to refine Pocillopora species boundaries, (2) the relevance of the mtORF (coupled with other markers in some cases) as a diagnostic marker of most species, (3) the requirement of molecular identification when species identity of colonies is absolutely necessary to interpret results, as morphology can blur species identification in the field, and (4) the need for a taxonomic revision of the genus Pocillopora. These results give new insights into the usefulness of multiple criteria for resolving Pocillopora, and more widely, scleractinian species boundaries, and will ultimately contribute to the taxonomic revision of this genus and the conservation of its species

    Assessment of the distribution of Ruditapes spp. in northern Mediterranean sites using morphological and genetic data

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    International audienceIn the 1970s, Ruditapes philippinarum was introduced to France at Arcachon Bay for aquaculture. At present, in Europe, R. philippinarum is often found in place of the native species Ruditapes decussatus. The aim of this study is to evaluate the distribution of these two species along the northern Mediterranean coastline using morphological and morphometric analysis. The sampling period was between June and December 2018. Among the 11 French sites, only 2 contained R. philippinarum, whereas only the indigenous species was present at the other sites. Genetic analyses were used to confirm species identity and to confirm this distribution. A site in Italy, Pialassa Baiona, was also added to the sample. This analysis of Ruditapes from multiple French sites and one Italian site highlights species-level differences in shell morphology between R. decussatus and R. philippinarum. The intraspecific morphometric analysis showed the presence of different groups depending on spatial scales (i.e. at the large scale, between the Mediterranean Sea and the Atlantic, and on the small scale, that is within the Berre lagoon in France. No relationship between morphometric and genetic variation was found. This suggests that the differences in the shell shape of Ruditapes are driven by local environmental conditions

    Species and population genomic differentiation in Pocillopora corals (Cnidaria, Hexacorallia)

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    International audienceCorrectly delimiting species and populations is a prerequisite for studies of connectivity, adaptation and conservation. Genomic data are particularly useful to test for species differentiation for organisms with few informative morphological characters or low discrimination of cytoplasmic markers, as in Scleractinians. Here we applied Restriction site Associated DNA sequencing (RADsequencing) to the study of species differentiation and genetic structure in populations of Pocillopora spp. from Oman and French Polynesia, with the objectives to test species hypotheses, and to study the genetic structure among sampling sites within species. We focused here on coral colonies morphologically similar to P. acuta (damicornis type 尾). We tested the impact of different filtering strategies on the stability of the results. The main genetic differentiation was observed between samples from Oman and French Polynesia. These samples corresponded to different previously defined primary species hypotheses (PSH), i.e. PSHs 12 and 13 in Oman, and PSH 5 in French Polynesia. In Oman, we did not observe any clear differentiation between the two putative species PSH 12 and 13, nor between sampling sites. In French Polynesia, where a single species hypothesis was studied, there was no differentiation between sites. Our analyses allowed the identification of clonal lineages in Oman and French Polynesia. The impact of clonality on genetic diversity is discussed in light of individual-based simulations

    Biodiversity, climate change, and adaptation in the Mediterranean

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    Potential for, and limits to, adaptation to environmental changes are critical for resilience and risk mitigation. The Mediterranean basin is a mosaic of biodiversity-rich ecosystems long affected by human influence, whose resilience is now questioned by climate change. After reviewing the different components of biological adaptation, we present the main characteristics of marine and terrestrial biodiversity in the Mediterranean basin and of the pressures they face. Taking climatic trends into consideration, we discuss the adaptive potential of a range of ecosystems dominated by species without active dispersal. We argue that the high heterogeneity of Mediterranean landscapes and seascapes constitutes a laboratory for the study of adaptation when environmental conditions change rapidly and may provide opportunities for adaptation and adaptability of species and ecosystems. Adaptive management in the Mediterranean can and should harness the nature-based solutions offered by both ecological and evolutionary processes for increasing the resilience of ecosystems to climate change
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