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Relation between mitochondrial DNA hyperdiversity, mutation rate and mitochondrial genome evolution in Melarhaphe neritoides (Gastropoda: Littorinidae) and other Caenogastropoda
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Mitochondrial DNA hyperdiversity is primarily caused by high mutation rates (µ) and has potential implications for mitogenome architecture and evolution. In the hyperdiverse mtDNA of Melarhaphe neritoides (Gastropoda: Littorinidae), high mutational pressure generates unusually large amounts of synonymous variation, which is expected to (1) promote changes in synonymous codon usage, (2) reflect selection at synonymous sites, (3) increase mtDNA recombination and gene rearrangement, and (4) be correlated with high mtDNA substitution rates. The mitogenome of M. neritoides was sequenced, compared to closely related littorinids and put in the phylogenetic context of Caenogastropoda, to assess the influence of mtDNA hyperdiversity and high µ on gene content and gene order. Most mitogenome features are in line with the trend in Mollusca, except for the atypical secondary structure of the methionine transfer RNA lacking the TΨC-loop. Therefore, mtDNA hyperdiversity and high µ in M. neritoides do not seem to affect its mitogenome architecture. Synonymous sites are under positive selection, which adds to the growing evidence of non-neutral evolution at synonymous sites. Under such non-neutrality, substitution rate involves neutral and non-neutral substitutions, and high µ is not necessarily associated with high substitution rate, thus explaining that, unlike high µ, a high substitution rate is associated with gene order rearrangement.
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RBINS Staff Publications 2018
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A scientific name for Pacific oysters
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RBINS Staff Publications 2018
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The Devonian–Carboniferous boundary in Belgium and surrounding areas
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The Devonian–Carboniferous boundary is associated with a major extinction event of the Phanerozoic. It was also a time marked by a rapid but short-lasting change in deposition called Hangenberg Event. In the Namur–Dinant Basin the uppermost Devonian (‘Strunian’) deposits recorded a third-order transgression that produced a progressive switch from coastal siliciclastic to proximal mixed deposits with an increase of the carbonate production on the ramp. Hence, the Comblain-au-Pont and lower Hastière formations are considered as the transgressive system tract, whereas the middle member of the Hastière Formation is interpreted as the highstand system tract, capped by an erosion surface corresponding to the third-order sequence boundary. Superimposed on these third-order sequences are well-marked orbitally forced precession cycles (wet–dry climate alternations) of c. 18.6 ka, appearing as irregular c. 30–80-cm-thick couplets of limestone and calcareous shale beds. The Hangenberg Black Shale Event is locally present as dark shales that likely spread over the shelf, marking the maximum flooding surface of the sequence. Before and after this event, carbonate facies rich in benthic macrofauna and microfauna continued to develop. The Hangenberg Sandstone Event, appearing as a sandstone bed in pelagic sections, is variously recorded at the base of the Hastière Formation, either as a sandy siltstone bed in proximal sections or as a horizon with limestone clasts and reworked fossils in more distal settings. The Hangenberg Sandstone Event beds occur sharply in the stratigraphic record and do not correspond to the long sea level fall of a third-order sequence boundary, but most probably to a short out-of-sequence event. The revision of the stratigraphic distribution of major fossil groups pleads for a continuous biostratigraphic succession with no obvious hiatus. The variable development of some micropalaeontological zones at the end of the Devonian is the result of complex ecobiostratigraphic interactions with the environment rather than the reflection of true hiatuses. It is marked by extinctions of Devonian taxa, concomitantly with the end of the reworking produced by the Hangenberg Sandstone Event, most probably immediately below the entry of the conodont Protognathodus kockeli. It is also coincident with the boundary between the foraminiferal zones DFZ7–MFZ1, rugose coral zones RC0–RC1 and between the palynozones LE–VI. After the short-lasting regressive phase of the Hangenberg Sandstone Event, normal depositional settings returned with the deposition of the Hastière Formation. Hence, the end of the Hangenberg Sandstone Event is proposed as the most natural proxy to pinpoint the Devonian– Carboniferous boundary.
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RBINS Staff Publications 2020
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A new basal ornithopod dinosaur from the Lower Cretaceous of China
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RBINS Staff Publications 2020
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CHEMICAL PRESERVATION OF TAIL FEATHERS FROM ANCHIORNIS HUXLEYI, A THEROPOD DINOSAUR FROM THE TIAOJISHAN FORMATION (UPPER JURASSIC, CHINA)
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RBINS Staff Publications 2020
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A new phylogeny of cerapodan dinosaurs
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RBINS Staff Publications 2020
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A new titanosaur (Dinosauria: Sauropoda) from the Upper Cretaceous of Velaux-La-Bastide Neuve (southern France)
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RBINS Staff Publications 2020
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Data of feather recovering performance of birds and micro structure of pigeons’ feathers
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RBINS Staff Publications 2020
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First annotated draft genomes of nonmarine ostracods (Ostracoda, Crustacea) with different reproductive modes
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Ostracods are one of the oldest crustacean groups with an excellent fossil record and high importance for phylogenetic analyses but genome resources for this class are still lacking. We have successfully assembled and annotated the first reference genomes for three species of nonmarine ostracods; two with obligate sexual reproduction (Cyprideis torosa and Notodromas monacha) and the putative ancient asexual Darwinula stevensoni. This kind of genomic research has so far been impeded by the small size of most ostracods and the absence of genetic resources such as linkage maps or BAC libraries that were available for other crustaceans. For genome assembly, we used an Illumina-based sequencing technology, resulting in assemblies of similar sizes for the three species (335–382 Mb) and with scaffold numbers and their N50 (19–56 kb) in the same orders of magnitude. Gene annotations were guided by transcriptome data from each species. The three assemblies are relatively complete with BUSCO scores of 92–96. The number of predicted genes (13,771–17,776) is in the same range as Branchiopoda genomes but lower than in most malacostracan genomes. These three reference genomes from nonmarine ostracods provide the urgently needed basis to further develop ostracods as models for evolutionary and ecological research.
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RBINS Staff Publications 2021
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On the first Belgian record of the Eifelian (Middle Devonian) ammonoid cephalopod Subanarcestes (Suborder Anarcestina)
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Ammonoid cephalopods are extremely rare in the Lower and Middle Devonian sedimentary rocks of Belgium, which contrasts with the neighboring sedimentary basins. However, searches in old collections and recent collecting efforts show that ammonoids do occur in these beds in Belgium, which allows to enlarge our knowledge of Lower and Middle Devonian ammonoid occurrences. Here, a record of the Eifelian (Middle Devonian) anarcestid ammonoid genus Subanarcestes is described for the first time from Belgium based on a specimen from the Jemelle Formation (Chavées Member). This specimen was collected more than a century ago by Eugène Maillieux at Trou Bodet near Couvin. It laid unrecognized as an ammonoid cephalopod for many decades in the collections of the Royal Belgian Institute of Natural Sciences, while being previously identified as Cryptoceras or ‘Nautilus’ fossil, which if correct, constituted Belgium’s oldest Nautilida fossil. Micro-CT imaging greatly helped in the taxonomic assignment of the specimen.
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RBINS Staff Publications 2023
