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Reduced contribution of sulfur to the mass extinction associated with the Chicxulub impact event
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The Chicxulub asteroid impact event at the Cretaceous-Paleogene (K-Pg) boundary ˊ66 Myr ago is widely considered responsible for the mass extinction event leading to the demise of the non-avian dinosaurs. Short-term cooling due to massive release of climate-active agents is hypothesized to have been crucial, with S-bearing gases originating from the target rock vaporization considered an important driving force. Yet, the magnitude of the S release remains poorly constrained. Here we empirically estimate the amount of impact-released S relying on the concentration of S and its isotopic composition within the impact structure and a set of terrestrial K-Pg boundary ejecta sites. The average value of 67 ± 39 Gt obtained is ˊ5-fold lower than previous numerical estimates. The lower mass of S-released may indicate a less prominent role for S emission leading to a milder impact winter with key implications for species survival during the first years following the impact.
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RBINS Staff Publications 2025 OA
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Reduced host-specificity in a parasite infecting non-littoral Lake Tanganyika cichlids evidenced by intraspecific morphological and genetic diversity
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Lake Tanganyika is well-known for its high species-richness and rapid radiation processes. Its assemblage of cichlid fishes recently gained momentum as a framework to study parasite ecology and evolution. It offers a rare chance to investigate the influence of a deepwater lifestyle in a freshwater fish-parasite system. Our study represents the first investigation of parasite intraspecific genetic structure related to host specificity in the lake. It focused on the monogenean flatworm Cichlidogyrus casuarinus infecting deepwater cichlids belonging to Bathybates and Hemibates. Morphological examination of C. casuarinus had previously suggested a broad host range, while the lake’s other Cichlidogyrus species are usually host specific. However, ongoing speciation or cryptic diversity could not be excluded. To distinguish between these hypotheses, we analysed intraspecific diversity of C. casuarinus. Monogeneans from nearly all representatives of the host genera were examined using morphometrics, geomorphometrics and genetics. We confirmed the low host-specificity of C. casuarinus based on morphology and nuclear DNA. Yet, intraspecific variation of sclerotized structures was observed. Nevertheless, the highly variable mitochondrial DNA indicated recent population expansion, but no ongoing parasite speciation, confirming, for the first time in freshwater, reduced parasite host specificity in the deepwater realm, probably an adaptation to low host availability.
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RBINS Staff Publications 2016
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Reduced plumage and flight ability of a new Jurassic paravian theropod from China
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Feathered theropods were diverse in the Early Cretaceous Jehol Group of western Liaoning Province, China. Recently, anatomically distinct feathered taxa have been discovered in the older Middle-Late Jurassic Tiaojishan Formation in the same region. Phylogenetic hypotheses including these specimens have challenged the pivotal position of Archaeopteryx in bird phylogeny. Here we report a basal troodontid from the Tiaojishan Formation that resembles Anchiornis, also from Jianchang County (regarded as sister-taxa). The feathers of Eosinopteryx are less extensive on the limbs and tail than Anchiornis and other deinonychosaurians. With reduced plumage and short uncurved pedal claws, Eosinopteryx would have been able to run unimpeded (with large foot remiges cursorial locomotion was likely problematic for Anchiornis). Eosinopteryx increases the known diversity of small-bodied dinosaurs in the Jurassic,shows that taxa with similar body plans could occupy different niches in the same ecosystem and suggests a more complex picture for the origin of flight.
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RBINS Staff Publications
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Reduced-representation sequencing detects trans-Arctic connectivity and local adaptation in polar cod (Boreogadus saida)
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Information on connectivity and genetic structure of marine organisms remains sparse in frontier ecosystems such as the Arctic Ocean. Filling these knowledge gaps becomes increasingly urgent, as the Arctic is undergoing rapid physical, ecological, and socio-economic changes. The abundant and widely distributed polar cod (Boreogadus saida) is highly adapted to Arctic waters, and its larvae and juveniles live in close association with sea ice. Through a reduced-representation sequencing approach, this study explored the spatial genetic structure of polar cod at a circum-Arctic scale. Genomic variation was partitioned into neutral and adaptive components to respectively investigate genetic connectivity and local adaptation. Based on 922 high-quality single nucleotide polymorphism (SNP) markers genotyped in 611 polar cod, broad-scale differentiation was detected among three groups: (i) Beaufort-Chukchi seas, (ii) all regions connected by the Transpolar Drift, ranging from the Laptev Sea to Iceland, including the European Arctic, and (iii) West Greenland. Patterns of neutral genetic structure suggested broadscale oceanographic and sea ice drift features (i.e. Beaufort Gyre and Transpolar Drift) as important drivers of connectivity. Genomic variation at 35 outlier loci indicated adaptive divergence of the West Greenland, and the Beaufort-Chukchi Seas populations, possibly driven by environmental conditions. Sea ice decline and changing ocean currents can alter or disrupt connectivity between polar cod from the three genetic groups, potentially undermining their resilience to climate change, even in putative refugia, such as the Central Arctic Ocean and the Arctic Archipelago.
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RBINS Staff Publications 2025
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Reducing marine eutrophication may require a paradigmatic change
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RBINS Staff Publications 2018
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Reevaluating the timing of Neanderthal disappearance in Northwest Europe
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Understanding when Neanderthals disappeared is a hotly debated topic. When radiocarbon dating placed the Spy Neanderthals amongst the latest surviving in Northwest Europe, questions were raised regarding the reliability of the dates. Using a procedure more efficient in removing contamination and ancient genomic analysis, we show that previous dates produced on Neanderthal specimens from Spy are too young by up to 10,000 y. Our direct radiocarbon dates on the Neanderthals from Spy and those from Engis and Fonds-de-Forêt show a reduction of the uncertainty for the time window corresponding to Neanderthal disappearance in Northwest Europe. This population disappeared at 44,200 to 40,600 cal B.P. (at 95.4% probability). This is also earlier than previous suggestions based on dates on bulk collagen.Elucidating when Neanderthal populations disappeared from Eurasia is a key question in paleoanthropology, and Belgium is one of the key regions for studying the Middle to Upper Paleolithic transition. Previous radiocarbon dating placed the Spy Neanderthals among the latest surviving Neanderthals in Northwest Europe with reported dates as young as 23,880 ± 240 B.P. (OxA-8912). Questions were raised, however, regarding the reliability of these dates. Soil contamination and carbon-based conservation products are known to cause problems during the radiocarbon dating of bulk collagen samples. Employing a compound-specific approach that is today the most efficient in removing contamination and ancient genomic analysis, we demonstrate here that previous dates produced on Neanderthal specimens from Spy were inaccurately young by up to 10,000 y due to the presence of unremoved contamination. Our compound-specific radiocarbon dates on the Neanderthals from Spy and those from Engis and Fonds-de-Forêt demonstrate that they disappeared from Northwest Europe at 44,200 to 40,600 cal B.P. (at 95.4% probability), much earlier than previously suggested. Our data contribute significantly to refining models for Neanderthal disappearance in Europe and, more broadly, show that chronometric models regarding the appearance or disappearance of animal or hominin groups should be based only on radiocarbon dates obtained using robust pretreatment methods.All the radiocarbon data generated at the ORAU are archived internally and are also available on the laboratory’s website, along with a link to the paper. The mitochondrial genome from Fonds-de-Forêt is deposited in GenBank with the accession number PRJEB39136. All other study data are included in the article and/or SI Appendix.
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RBINS Staff Publications 2021
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Regional differences in vertebral shape along the axial skeleton in caecilians (Amphibia: Gymnophiona)
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Abstract Caecilians are elongate, limbless and annulated amphibians that, as far as is known, all have an at least partly fossorial lifestyle. It has been suggested that elongate limbless vertebrates show little morphological differentiation throughout the postcranial skeleton. However, relatively few studies have explored the axial skeleton in limbless tetrapods. In this study, we used ?CT data and three-dimensional geometric morphometrics to explore regional differences in vertebral shape across a broad range of caecilian species. Our results highlight substantial differences in vertebral shape along the axial skeleton, with anterior vertebrae being short and bulky, whereas posterior vertebrae are more elongated. This study shows that despite being limbless, elongate tetrapods such as caecilians still show regional heterogeneity in the shape of individual vertebrae along the vertebral column. Further studies are needed, however, to understand the possible causes and functional consequences of the observed variation in vertebral shape in caecilians.
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RBINS Staff Publications 2022
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Regional environmental pressure influences population differentiation in turbot (Scophthalmus maximus).
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Unravelling the factors shaping the genetic structure of mobile marine species is challenging due to the high potential for gene flow. However, genetic inference can be greatly enhanced by increasing the genomic, geographical or environmental resolution of population genetic studies. Here, we investigated the population structure of turbot (Scophthalmus maximus) by screening 17 random and gene-linked markers in 999 individuals at 290 geographical locations throughout the northeast Atlantic Ocean. A seascape genetics approach with the inclusion of high-resolution oceanographical data was used to quantify the association of genetic variation with spatial, temporal and environmental parameters. Neutral loci identified three subgroups: an Atlantic group, a Baltic Sea group and one on the Irish Shelf. The inclusion of loci putatively under selection suggested an additional break in the North Sea, subdividing southern from northern Atlantic individuals. Environmental and spatial seascape variables correlated marginally with neutral genetic variation, but explained significant proportions (respectively, 8.7% and 10.3%) of adaptive genetic variation. Environmental variables associated with outlier allele frequencies included salinity, temperature, bottom shear stress, dissolved oxygen concentration and depth of the pycnocline. Furthermore, levels of explained adaptive genetic variation differed markedly between basins (3% vs. 12% in the North and Baltic Sea, respectively). We suggest that stable environmental selection pressure contributes to relatively strong local adaptation in the Baltic Sea. Our seascape genetic approach using a large number of sampling locations and associated oceanographical data proved useful for the identification of population units as the basis of management decisions.
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RBINS Staff Publications
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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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Reliability of AMS 14C dates of moss temper preserved in Neolithic pottery from the Scheldt river valley (Belgium).
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RBINS Staff Publications 2019
