Search publications of the members of the Royal Belgian institute of natural Sciences
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A heavyweight early whale pushes the boundaries of vertebrate morphology
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Advances in high-resolution paleoclimate reconstructions using growth experiments, age modelling and clumped isotope analyses
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Cirripedes (Thoracica, Crustacea) from the Maastrichtian of Kalaat Senan, Tunisia
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Archeobotanische resten van verversactiviteiten en textielbewerking uit laatmiddeleeuwse waterlopen, recente vondsten uit Brussel en Mechelen (Br. & Antw.)
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Continuity in intestinal parasite infection in Aalst (Belgium) from the medieval to the early modern period (12th-17th centuries)
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The Freshwater Animal Diversity Assessment (FADA): a taxonomic backbone for global biodiversity databases
- Koen Martens works at the Royal Belgian Institute of natural Sciences (Brussels, Belgium). He is guest professor at the UGent and visiting professor at the State University of Maringá (Brazil). His research interests are in aquatic ecology and evolutionary biology. He is editor in chief of Hydrobiologia since 2003. Freshwater covers less than 1% of the Earth’s surface, but 10% of all animals occur only in freshwaters, a discrepancy known as the “paradox of freshwater”. Several global data repositories (such as GBIF) document extant freshwater biodiversity, but require reliable taxonomic backbones. Currently, FADA (created by Koen in 2005) groups more than 125 thousand species and 11 thousand genera of freshwater animals. However, taxonomy is a living scientific discipline, where new taxa are being described and existing taxa are being placed in new taxonomic positions. infraFADA, a three-year BELSPO project, will develop FADA into a research infrastructure that serves as taxonomic backbone for a variety of global biodiversity databases.
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Multiple genetic species in a halophilic non-marine ostracod (Crustacea)
- The discovery of animal genetic (mostly also cryptic) species has known an exponential increase since molecular techniques became available. Also in non-marine ostracods (small, bivalved crustaceans with an excellent fossil record), several morphospecies have been shown to comprise several genetic species. Here, we screen 13 populations from Central Europe and the circum-Mediterranean region of the halophilic continental ostracod species Heterocypris salina with DNA sequences from a mitochondrial (COI) and a nuclear (28S) marker. We apply four species delimitation methods to show that this nominal species consists of four genetic species in both DNA datasets, and that these two sets of genetic species show mitonuclear discordance. Most investigated specimens belonged to one of these four genetic species. There was no clear correlation between geographic and genetic distances, but we found that, apart from historical processes, environmental factors such as ecoregion, seasonality and salinity might have been important drivers shaping discrete genetic diversity. Following the palaeontological literature, the H. salina species cluster is at least 11–9 Myr old.
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The Ostracod Clumped-Isotope Thermometer: A Novel Tool to Accurately Quantify Continental Climate Changes
- This study presents a methodological advancement in the field of clumped-isotope (∆47) thermometry, specifically tailored for application to freshwater ostracods. The novel ostracod clumped isotope approach enables quantitative temperature and hydrological reconstruction in lacustrine records. The relationship between ∆47 and the temperature at which ostracod shell mineralized is determined by measuring ∆47 on different species grown under controlled temperatures, ranging from 4 ± 0.8 to 23 ± 0.5ºC. The excellent agreement between the presented ∆47 ostracod data and the monitored temperatures confirms that ∆47 can be applied to ostracod shells and that a vital effect is absent outside the uncertainty of measurements. Results are consistent with the carbonate clumped-isotope unified calibration (Anderson et al., 2021, https://doi.org/10.1029/2020gl092069), therefore, an ostracod-specific calibration is not needed. The ostracod clumped-isotope thermometer represents a powerful tool for terrestrial paleoclimate studies all around the world, as lakes and ostracods are found in all climatic belts.
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Evidence for a single population expansion event across 24,000 km: the case of the deep‑sea scavenging amphipod Abyssorchomene distinctus
- Anthropogenic activities such as mining pose a putative threat to deep-sea ecosystems and baseline studies of key indicator species are required to assess future loss of biodiversity. We examined population genetic structure, connectivity, cryptic diversity and phylogeography of the deep-sea scavenging amphipod, Abyssorchomene distinctus, using DNA sequence data (mitochondrial COI and nuclear 28S genes) from 373 specimens collected from six abyssal basins. We observed a striking absence of cryptic diversity, suggesting a single, widely distributed species in the Pacifc and Indian Ocean. A single event of population expansion across distances up to 24,000 km is further supported by a main ancestral haplotype in the star-like shaped COI haplotype network, a skewed nucleotide mismatch distribution and deviations from evolutionary neutrality tests. In the Pacifc, A. distinctus showed weak genetic population structure and low diferentiation between the basins of the Clarion-Clipperton Zone and the DISCOL Experimental Area, suggesting a possible higher chance of recovery from deep-sea mining impacts. However, since our data indicate a single recent historic population expansion event, A. distinctus populations will likely be afected to unknown extents, as the exact drivers shaping distribution and dispersion of A. distinctus are still unclear
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infraFADA: Upgrading the taxonomic backbone of global freshwater animal biodiversity research infrastructures
- The current Freshwater Animal Diversity Assessment (FADA) comprises an extensive set of global taxa lists for freshwater animal groups. At present, more than 125 thousand described freshwater animal species in more than 11 thousand genera have been documented. However, taxonomy is a living scientific discipline, where new taxa are continuously being described, and existing taxa are being placed in new taxonomic positions. Therefore, after a period of relative inactivity, the BELSPO (Belgian Science Policy) project “infraFADA” (2023-2026) re-establishes the global FADA consortium of taxonomic experts, so that all taxa lists will be brought up to date, both technically and in terms of content. infraFADA will develop a living, updated, and global FADA database, fully in open access and according to the FAIR principles. The infraFADA database is intended for use and consultation by the scientific freshwater community, as well as for interested stakeholders, for example, freshwater ecosystem managers, biodiversity conservationists, and others. Most importantly, FADA will also serve as a taxonomic backbone for other global biodiversity data infrastructures, such as the Catalogue of Life (CoL), the Global Biodiversity Information Facility (GBIF), the Freshwater Information Platform (FIP), and others. As such, FADA will provide a digital and living heritage of freshwater data, building bridges between science and society and helping to sustainably maintain freshwater resources.
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An endemic species flock of Candonidae Kaufmann, 1900 (Crustacea, Ostracoda) from wells in Benin (West Africa), with the description of a new subfamily, a new genus and five new species
- Between 2015 and 2022, over 200 wells were sampled in four catchment areas of Benin, using both Cvetkov plankton nets (funnel 200 μm mesh size, 150 μm below valve) and baited traps. As artificial wells serve as ecotones (interfaces between surface and groundwater ecosystems), the ostracod fauna is mostly represented by two families; Cyprididae (mainly epigeic) and Candonidae (hypogeic). Here, we describe a new subfamily of Candonidae from the wells in Benin, the Benincandoninae subfam. nov. Hotèkpo & Martens, represented by one genus, Benincandona gen. nov. Hotèkpo & Martens. we found 35 species belonging to this evolutionary radiation, of which we describe five new species: Benincandona martini gen. et spec. nov. Hotèkpo & Martens, B. ibikounlei gen. et spec. nov. Hotèkpo & Martens, B. sakitii gen. et spec. nov. Hotèkpo & Martens, B. cebios gen. et spec. nov. Hotèkpo & Martens and B. trapezoides gen. et spec. nov. Hotèkpo & Martens. The new subfamily and genus are characterised by a unique combination of characters, such as a seven-segmented antennula and a caudal ramus with a fully developed ramus, a single apical (anterior) claw and three short setae. Species within the genus can be distinguished by their carapace and hemipenis morphology, together with some limb characteristics. whereas extensive subterranean candonid radiations have previously been reported from Europe, North and Central America and Northwest Australia (Pilbara), this is the first time such a vast radiation of subterranean candonids is reported from (west) Africa.
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Local factors drive the richness, biomass and composition of benthic invertebrate communities in Neotropical reservoirs
- Dams affect aquatic biota in running water by altering the environmental dynamics. One of the communities affected are benthic invertebrates, that perform important functions such as nutrient cycling and energy transfer in reservoirs. We investigated the influence of the following factors: spatial, abiotic variables, reservoir characteristics and land use on the richness, biomass and composition of benthic invertebrates in 29 reservoirs in southern Brazil. Sediment samples and abiotic variables were collected in the littoral and profundal zones of reservoirs during the dry (July) and rainy (November) seasons in 2001. We used principal coordinates of neighbour matrices to obtain the spatial factors. We analysed the unique and overall effects of the four factors. We found that the factors analysed significantly influenced the composition and biomass of the invertebrates (22%). The percentage of variation explained by the unique effects of the different factors showed similar values, but the spatial factors showed the highest value (4%). This indicates that closer reservoirs have higher similarities in terms of composition and biomass of benthic invertebrates. On the other hand, the abiotic variables had the highest explained value when evaluating the overall effects (10%). Therefore, for invertebrate richness, only the reservoir characteristics were significant for the overall and unique effects (49%). More specifically, we observed lower taxon richness in older reservoirs, probably because the age of such artificial aquatic ecosystems influences other variables, which structure the benthic communities. In conclusion, the structure of benthic invertebrate communities in reservoirs of southern Brazil are mainly driven by spatial and reservoir characteristics.
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Environmental factors and UV exposure affect gene activity in the putative ancient asexual ostracod Darwinula stevensoni
- The non-marine ostracod Darwinula stevensoni (Ostracoda, Crustaceae) is one of the last remaining examples of an ancient asexual (Schön et al. 2009) and has probably abandoned sexual reproduction approximately 20 million years ago (Straub 1952). In spite of the limited genetic diversity of D. stevensoni, its cosmopolitan distribution in different aquatic habitats indicate that this species can survive asexually in the long-term, possibly because it developed a general purpose genotype (Van Doninck et al. 2002). To unravel the genetic background of this general purpose genotype, we have studied gene activity of D. stevensoni via the RNA sequencing of transcriptomes. The transcriptome is the collection of all active genes which have been transcribed from DNA to RNA under certain conditions. Statistically comparing the genetic composition of transcriptomes allows us to identify differences in active (or expressed) genes, which inform on host adaptations to specific conditions. We characterised transcriptomes of D. stevensoni from natural populations in Spain, England and Belgium. To summarize results in our multi-gene approach, the “gene ontology” (GO) classification system was used which divides genes across groups (“terms”) in accordance to the biological function, molecular pathway or cellular component they affect. Of the 5013 terms which were assessed regarding biological function, 49 were found to have significantly different gene expression between the three different populations. However, none of these terms could be directly linked to temperature-related functions, suggesting that differences in gene expression between natural D. stevensoni populations are more complex and do not only reflect adaptation to varying temperature ranges. Living D. stevensoni individuals from the Belgian population were also exposed to UV-radiation in the lab. In this experiment, we expected to find an increased activity of genes being related to the repair and preservation of DNA countering the effects of UV-radiation. Of the same 5013 analysed gene terms, only 9 showed a significant change in gene expression in response to UV-radiation. None of these gene term had known repair functions, potentially highlighting again more complex gene expression patterns in D. stevensoni than initially expected. More analyses are currently ongoing to unravel the functionality of the activated genes in more detail. We are also planning an experimental set up to directly study gene expression differences of D. stevensoni under different temperatures.
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infraFADA: Upgrading the taxonomic backbone of global freshwater animal biodiversity research infrastructures
- The current Freshwater Animal Diversity Assessment (FADA) comprises an extensive set of global taxa lists for freshwater animal groups. At present, more than 125 thousand described freshwater animal species in more than 11 thousand genera have been documented. However, taxonomy is a living scientific discipline, where new taxa are continuously being described, and existing taxa are being placed in new taxonomic positions. Therefore, after a period of relative inactivity, the BELSPO (Belgian Science Policy) project “infraFADA” (2023-2026) re-establishes the global FADA consortium of taxonomic experts, so that all taxa lists will be brought up to date, both technically and in terms of content. infraFADA will develop a living, updated, and global FADA database, fully in open access and according to the FAIR principles. The infraFADA database is intended for use and consultation by the scientific freshwater community, as well as for interested stakeholders, for example, freshwater ecosystem managers, biodiversity conservationists, and others. Most importantly, FADA will also serve as a taxonomic backbone for other global biodiversity data infrastructures, such as the Catalogue of Life (CoL), the Global Biodiversity Information Facility (GBIF), the Freshwater Information Platform (FIP), and others. As such, FADA will provide a digital and living heritage of freshwater data, building bridges between science and society and helping to sustainably maintain freshwater resources.
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Hematodinium perezi (Dinophyceae: Syndiniales) in Morocco: The First Record on the African Atlantic Coast and the First Country Record of a Parasite of the Invasive Non-Native Blue Crab Callinectes sapidus
- Dinoflagellates belonging to the genus Hematodinium are key parasites of marine crustaceans, primarily decapods. In this study, we document the first report of H. perezi Chatton & Poisson, 1930 on the African Atlantic coast. This is also the first parasite record in the invasive non-native Atlantic blue crab Callinectes sapidus Rathbun, 1896 in Morocco. Specimens of C. sapidus were sampled in winter 2023 from two Ramsar sites on the Moroccan Atlantic, namely Merja Zerga and Oualidia Lagoons, and were screened to detect the presence of parasites in their hemolymph. Based on staining fresh hemolymph smears, we did not detect Hematodinium in any of the 36 investigated individuals (20 and 16 from Merja Zerga and Oualidia Lagoons, respectively), probably due to methodological artifacts. The PCR-based method was revealed to be more accurate in diagnosing the Hematodinium parasite. It showed that at Merja Zerga Lagoon, 13 individuals of C. sapidus were infected by the parasite (prevalence: 65%) in comparison to four at Oualidia Lagoon (25%). Genetic analysis, based on the ITS1 rDNA gene from Hematodinium, confirmed the sequences as being those of Hematodinium perezi.
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High-resolution description of insular and fjordic benthic food webs along the West Antarctic Peninsula
- The West Antarctic Peninsula (WAP) is one of the most rapidly warming region on Earth. In this context, it is crucial to improve our understanding of the consequences of future changes in the local biotic and abiotic environments on marine ecosystem functioning. Here, we focused on food web structure of shallow-water benthic communities. In February 2023, the TANGO1 expedition, using a sailboat, brought nine Belgian scientists to the WAP. To assess the importance of environmental changes on local food web dynamics, five benthic communities were investigated, focusing on macroalgae forests (n=2) and sedimentary soft bottoms (n=3). These stations were distributed between two contrasted environments, Dodman Island (Grandidier Channel, 66°S) & Blaiklock Island (Bigourdan Fjord, 67.5°S). These two locations differed markedly in terms of sea-ice cover, and in terms of general hydrography (small island exposed to the Grandidier Channel’s currents VS fjord system surrounded by active glaciers). At each station, basal food sources (i.e. sediment-associated POM, water-column POM, macroalgae, microphytobenthos) as well as benthic invertebrates (435 individuals, 64 morphospecies) were sampled quantitatively to assess their biomass, and for later stable isotope analysis. Using stable isotope ratios of carbon, nitrogen and sulphur, and Bayesian tools, we aim to formally represent the communities in isotopic space, and to compare their topologies along the environmental gradient studied. These representations will then be used to test whether differences in food web structure reflect general community characteristics, such as the higher biomass of organisms measured in macroalgae forests, which also display the greatest species diversity.
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Otolith morphology of mesopelagic fishes collected from the Irminger Sea, North Atlantic Ocean
- A large series of otoliths of 16 mesopelagic teleost fish species from the Irminger Sea, North Atlantic Ocean, are described morphologically to investigate the ontogenetic and intraspecific variation. The results show that the surface morphology of the otoliths between young and adult specimens is variable, especially in the alepocephaliform (Normichthys operosus, Sagamichthys schnakenbecki, Xenodermichthys copei) and astronesthine (Borostomias antarcticus) species. The diagnostic features of the otoliths can be used to confirm the identity of the species, especially in myctophids, where confusion between Benthosema glaciale and Myctophum punctatum may be possible. A SEM-based iconography of the otoliths of all studied species is presented.
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Detection of invasive and alien land planarians as threats to agriculture and ecosystem stability
- Alien land planarians are considered potential threats to European agriculture and ecosystem stability. Severe impact of alien land planarian species in Europe but also worldwide was reported including depletion of local and native soil invertebrates and possible detrimental changes at the ecosystem level. Given the increasing number of studies reporting non-native and potentially invasive species of geoplanid planarians, further action in first response related to worldwide plant trade is called for. To date, the only flatworm on the list of “Invasive Alien Species of European Union Concern” is the New Zealand flatworm Arthurdendyus triangulatus. To help authorities detect and prevent introduction of the New Zealand flatworm, we designed an experiment in order to develop a species-specific barcoding protocol to check possible contamination by A. triangulatus of containerised flowerpots, identified as the most probable source of its co-introduction to non-native region. Based on our results, specific behavior of A. triangulatus staying restricted to the surface and upper layer of the flowerpot determines accessibility of DNA in the soil. Therefore, water-based eDNA methodology combined with a newly established qPCR protocol is preferred as it provides a sensitive approach for detection of A. triangulatus in the flowerpots. Further testing is needed to determine sensitivity of the persistence of eDNA following the flatworm’s removal, to estimate the risk of false positives. The newly designed barcoding protocols provide species-specific diagnosis of one invasive and three non-native land planarians currently being assessed for their invasion risks. However, the species-specificity of the developed barcoding protocols might need to be re-evaluated in case of introduction of new planarian species, and in view of apparent misidentifications regarding published genetic resources. Instead, general protocols requiring genetic sequence analyses would offer a more robust approach to assess species diversity of introduced and potentially invasive land planarians.
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Parasitic monogenean flatworms as tags for invasive aquatic vertebrates in africa, using mitochondrial markers and historical collections
- Reasons why introduced alien species are major risks to biodiversity include parasite co-introduction and lateral transfer to local hosts, but this parasitological impact is understudied. The origins and identities of introduced organisms are often unknown, including those of their parasite fauna. Recent species monitoring only provides partial answers for want of baseline data: especially in the Global South and in sub-Saharan Africa in particular, where native parasite biodiversity is poorly known. We studied introduced vertebrates (cichlids, sardines, frogs) in Central and Southern African inland waters, and parasitic flatworms (monogeneans) infecting them. Given their obligate one-host lifestyle, these parasites are thought to be more easily co-introduced with their hosts, and to be used as “tags” for the origin and introduction pathway of host populations. Parasites were isolated from hosts sampled from historical collections and in recent fieldwork. Monogenean parasites were morphologically identified to species level, and characterised using nuclear and mitochondrial markers. Using historical fish collections to reconstruct pre-introduction baselines for cichlid parasite communities, we distinguished between native and co-introduced parasite species, and detected parasite transmission to native cichlids. Monogeneans helped identify origins and introduction pathways of invasive sardines. For the notoriously invasive Nile tilapia and African clawed frog, these parasites provided a higher resolution than host genetics. This a proof-of-concept of biodiversity infrastructure and parasites as information sources for invasion biology. Nevertheless, a review of the state-of-the-art of parasitological research on Nile tilapia, an invasive f ish of global economic and ecological importance, shows that work on its parasites mostly overlooks their indicator potential. We recommend more scientific consideration to the parasites of invasive species, using a more integrative approach than is currently often taken.
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Exploring co-invasion dynamics: parasitic interactions in the wake of Nile perch invasion in Lake Victoria and its impact on the parasite fauna of haplochromine cichlids
- Biological invasions represent a significant threat to global biodiversity, impacting ecosystems and altering ecological dynamics. The introduction of the Nile perch (Lates niloticus) into Lake Victoria (East Africa), has led to ecological transformations, influencing the native fish communities. While much attention has been devoted to studying the ecological impacts of the Nile perch invasion on the native fish fauna and socio-economic consequences, little is known about the co-introduction dynamics of its potentially co-invasive parasites, as well as the impact on the gill macroparasite fauna of the native fishes impacted by the invasion (e.g. haplochromine cichlids). To investigate the co-introduction dynamics, we assessed the genetic and morphological diversity of Dolicirroplectanum lacustre, the only flatworm (Monogenea) parasite that infects lates perches across Africa. We found that D. lacustre was co-introduced with L. niloticus. In Lake Victoria, we found a reduction in the genetic and morphological diversity of D. lacustre compared with its native range, indicating a founder effect. To examine the broader ecological consequences of Nile perch invasion and human-induced eutrophication, we compared gill macroparasite communities of 13 native haplochromine cichlid species before and after these perturbations. We observed a reconfiguration of the host-parasite network that buffers the impacts of perturbations, indicating resilience. However, we observe a decrease in parasite-host range and infection parameters, highlighting the vulnerability of parasite communities to ongoing environmental changes associated with biological invasions. These findings underscore the importance of understanding the intricate dynamics of host-parasite interactions in the context of biological invasions and environmental change. By integrating insights from the invasive species dynamics and ecological perturbations, we provide valuable insights into the challenges and opportunities for conservation efforts to preserve ecosystem health and resilience in the face of global change.
