Search publications of the members of the Royal Belgian institute of natural Sciences
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The Middle Devonian plant assemblage from Dechra Aït Abdallah (Central Morocco) revisited
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Fifteen microsatellite loci for the decollate snail, Rumina decollata.
- We characterized 15 microsatellite loci from the decollate snail, Rumina decollata. Loci were screened in 21 individuals and several individuals of the congener Rumina saharica. There was ample allelic diversity (6–12 alleles per locus) but observed heterozygosity values were extremely low (0–0.421). This was expected given the high self-fertilization rate in this species. Ten of the 15 loci were successfully amplified in R. saharica. These loci provide tools for examining the population genetics and taxomomic boundaries in R. decollata and its allies.
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Optimisation of Polymerase Chain Reaction for Detection of Clostridium botulinum Type C and D in Bovine Samples.
- Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. The economic, medical and alimentary consequences can be catastrophic in case of an epizooty. A polymer-ase chain reaction (PCR)-based assay was developed for the detection of C. botulinumtoxigenic strains type C and D in bovine samples. This assay has proved to be less expensive, faster and simpler to use than the mouse bioassay, the current reference method for diagnosis of C. botulinum toxigenic strains. Three pairs of primers were designed, one for global detection of C. botulinum types C and D (primer pair Y), and two strain-specific pairs specifically designed for types C (primer pair VC) and D (primer pair VD). The PCR amplification conditions were optimized and evaluated on 13 bovine and two duck samples that had been previously tested by the mouse bioassay. In order to assess the impact of sample treatment, both DNA extracted from crude sam-ples and three different enrichment broths (TYG, CMM, CMM followed by TYG) were tested. A 100% sensitivity was observed when samples were enriched for 5 days in CMM followed by 1 day in TYG broth. False-negative results were encountered when C. botulinum was screened for in crude samples. These findings indicate that the current PCR is a reliable method for the detection of C. botulinum toxigenic strains type C and D in bovine samples but only after proper enrichment in CMM and TYG broth
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Defense by Volatiles in Leaf-Mining Insect Larvae
- Abstract The defense strategy of an insect toward natural enemies can include a trait that appears at first sight to contradict its defensive function. We explored phylogeny, chemistry, and defense efficiency of a peculiar group of hymenopteran sawfly larvae where this contradiction is obvious. Pseudodineurini larvae live in leaf mines that protect them from some enemies. Disturbed larvae also emit a clearly perceptible lemon-like odor produced by ventral glands, although the mine hampers the evaporation of the secretion. The mine could also lead to autointoxication of a larva by its own emitted volatiles. Citral was the major component in all Pseudodineurini species, and it efficiently repels ants. We conclude that full-grown larvae that leave their mine to pupate in the soil benefit from citral by avoiding attacks from ground-dwelling arthropods such as ants. In some species, we also detected biosynthetically related compounds, two 8-oxocitral diastereomers (i.e., (2E,6E)- and (2E,6Z)-2,6-dimethylocta-2,6-dienedial). Synthetic 8-oxocitral proved to be a potent fungicide, but not an ant repellent. The discrete distribution of 8-oxocitral was unrelated to species grouping in the phylogenetic tree. In contrast, we discovered that its presence was associated with species from humid and cold zones but absent in species favoring warm and dry environments. The former should be protected by 8-oxocitral when faced with a fungal infestation while crawling into the soil. Our work shows the importance of integrating knowledge about behavior, morphology, and life history stages for understanding the complex evolution of insects and especially their defense strategies.
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Towards a revision of the Neotropical soldierless termites (Isoptera : Termitidae): redescription of the genus Anoplotermes and description of Longustitermes, gen. nov.
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Incongruence between molecular phylogeny and morphological classification in amphipod crustaceans: A case study of Antarctic lysianassoids
- In Antarctic waters, the superfamily Lysianassoidea is one of the most important amphipod groups both in terms of species number and abundance. Dominant members of this superfamily are species of the orchomenid complex, found throughout the Southern Ocean. This study presents the first molecular phylogenetic analysis based on a representative subset of the Antarctic species belonging to different orchomenid genera and hence provides a framework for a systematic revision of these taxa. The current classification of the orchomenid genera is mainly based on mouthpart morphology. The validity of these morphological characters was assessed by resolving phylogenetic relationships using nuclear 28S rRNA and mitochondrial cytochrome oxidase subunit I sequences. The molecular data rejected most of the previously proposed taxonomic subdivisions within this complex. The genera Abyssorchomene and Orchomenella as well as the subgenus Orchomenopsis appeared to be non-monophyletic. This implies that the supposed diagnostic characters are likely a result of convergent evolution. Further, our results indicated the necessity of a revision of the family-level systematics.
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The Francesʼ Sparrowhawk Accipiter francesiae (Aves: Accipitridae) radiation on the Comoro islands
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DNA barcoding and evolutionary relationships in Accipiter Brisson, 1760 (Aves, Falconiformes: Accipitridae) with a focus on African and Eurasian representatives
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Host Shifts from Lamiales to Brassicaceae in the Sawfly Genus Athalia
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First Large-Scale DNA Barcoding Assessment of Reptiles in the Biodiversity Hotspot of Madagascar, Based on Newly Designed COI Primers
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Identification of forensically important Sarcophaga species (Diptera: Sarcophagidae) using the mitochondrial COI gene
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Why is the molecular identification of the forensically important blowfly species Lucilia caesar and L. illustris (family Calliphoridae) so problematic?
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"Speleothèmes" à l'Institut des Sciences Naturelles
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The Parvidrilidae – a diversified groundwater family: description of six new species from southern Europe, and clues for its phylogenetic position within Clitellata (Annelida)
- The Parvidrilidae Erséus, 1999 constitute the most recently described family of oligochaete microdriles. Prior to this study, Parvidrilus strayeri Erséus, 1999, and Parvidrilus spelaeus Martínez-Ansemil, Sambugar & Giani, 2002, found in groundwaters of the USA (Alabama) and Europe (Slovenia and Italy), respectively, were the only two species in this family. In this paper, six new species – Parvidrilus camachoi, Parvidrilus gianii, Parvidrilus jugeti, Parvidrilus meyssonnieri, Parvidrilus stochi, and Parvidrilus tomasini – and Parvidrilus gineti (Juget, 1959) comb. nov. are added to the family. With all species being stygobiont, the Parvidrilidae is unique in being the only family of oligochaetes worldwide comprising taxa that are restricted to groundwater habitats. Parvidrilids are exceedingly small worms whose principal morphological characteristics are the presence of hair setae in ventral bundles, the markedly posterior position of setae within the segments, the presence of mid-dorsal glandular pouches in mesosomial segments, the lateral development of the clitellum, the presence of a single male pore in segment XII, and the presence (or absence) of a single spermatheca. The phylogenetic relationships of the Parvidrilidae within the Clitellata were investigated using the nuclear 18S rRNA gene, and the most representative and taxonomically balanced data set of clitellate families available to date. The data were analysed by parsimony, maximum likelihood, and Bayesian inference. Irrespective of the method used, Parvidrilidae were placed far from Capilloventridae, one family once suggested to be closely related to parvidrilids. Although closer to Enchytraeidae than Phreodrilidae, two other suggested putative sister families, the exact position of Parvidrilidae within Clitellata still remained uncertain in the absence of branch support. The examination of reproductive structures, together with the similarity of other important anatomical traits of the new species herein described, reinforced the idea that phreodrilids were the best candidate to be the sister group to parvidrilids on morphological grounds. A fragment of the mitochondrial cytochrome oxidase I gene, used as a barcode, also genetically characterized a few Parvidrilus species. The observation that two species diverge from each other by high genetic distances, even though their type localities are more or less only 100 km apart, is interpreted in the context of low dispersal abilities of inhabitants of the subterranean aquatic ecosystem, and habitat heterogeneity. The Parvidrilidae appear to be a diversified, Holarctic, and probably widely distributed family in groundwater, but very often overlooked because of the small size and external similarity with the polychaete family Aeolosomatidae of its members.
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Possible effects of global environmental changes on Antarctic benthos : a synthesis across five major taxa
- Because of the unique conditions that exist around the Antarctic continent, Southern Ocean (SO) ecosystems are very susceptible to the growing impact of global climate change and other anthropogenic influences. Consequently, there is an urgent need to understand how SO marine life will cope with expected future changes in the environment. Studies of Antarctic organisms have shown that individual species and higher taxa display different degrees of sensitivity to environmental shifts, making it difficult to predict overall community or ecosystem responses. This emphasizes the need for an improved understanding of the Antarctic benthic ecosystem response to global climate change using a multitaxon approach with consideration of different levels of biological organization. Here, we provide a synthesis of the ability of five important Antarctic benthic taxa (Foraminifera, Nematoda, Amphipoda, Isopoda, and Echinoidea) to cope with changes in the environment (temperature, pH, ice cover, ice scouring, food quantity, and quality) that are linked to climatic changes. Responses from individual to the taxon-specific community level to these drivers will vary with taxon but will include local species extinctions, invasions of warmer-water species, shifts in diversity, dominance, and trophic group composition, all with likely consequences for ecosystem functioning. Limitations in our current knowledge and understanding of climate change effects on the different levels are discussed.
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Guide taxonomique des oligochètes dulçaquicoles du Maghreb
- Résumé Ce guide fournit l’information taxonomique pour les 68 espèces d’oligochètes dulçaquicoles connus à l’heure actuelle au Maghreb, au sens strict, c’est-à-dire la région d’Afrique du nord qui regroupe le Maroc, l’Algérie et la Tunisie. Au niveau du Grand Maghreb, ce guide est potentiellement valable pour la Libye mais pas pour la Mauritanie. Une introduction est faite au milieu dulçaquicole du Maghreb et sa spécificité pour les oligochètes, ainsi qu’une présentation de la biologie et la diversité globale des oligochètes. Les récentes avancées dans le domaine de la nomenclature et de la classification du groupe sont intégrées. Un panorama détaillé des familles maghrébines d’oligochètes est dressé, précédé par des introductions à l’anatomie générale et aux caractères taxonomiques des oligochètes. Les aspects pratiques liés à l’échantillonnage et les techniques de préparation des spécimens et leur conservation sont détaillés, ainsi que les étapes à suivre pour les identifier. Une clé d’identification au niveau spécifique est fournie pour chaque famille, valable uniquement pour les oligochètes connus à l’heure actuelle au Maghreb, mais en précisant les espèces susceptibles d’y être rencontrées en raison de leur distribution biogéographique présente. Enfin, ce guide donne la description d’Aktedrilus yacoubii (Naididae, Phallodrilinae), espèce nouvelle pour la science et le Maghreb. Mots-clés – Clitellata, oligochètes dulçaquicoles, Maghreb, clés d’identification, taxonomie, liste d’espèces, échantillonnage, préparation de spécimens. Abstract This guide provides taxonomical information for the 68 freshwater oligochaete species known to date in Maghreb sensu stricto, namely this region of Northern Africa that includes Morocco, Algeria and Tunisia. At the “Grand Maghreb” level, the guide is potentially valid for Libya as well but not for Mauritania. An introduction to the freshwater environment of Maghreb and its peculiarity vis-à-vis the oligochaetes is given, as well as a presentation of the biology and general diversity of oligochaetes. Recent nomenclatural and classification advances are integrated. A comprehensive overview of Maghrebin oligochaete families is given, preceded by introductions into the general anatomy and taxonomic traits of oligochaetes. Practical aspects of sampling, and techniques of specimen preparation and conservation are detailed, as well as steps required for their identification. An identification key, at the species level, is provided for each family, only valid for oligochaetes presently known from Maghreb; however, species likely to be found in the future, because of their current biogeographic distribution, are also mentioned. Lastly, this guide gives the description of Aktedrilus yacoubii (Naididae, Phallodrilinae), a species new for science and Maghreb. Keywords – Clitellata, freshwater oligochaetes, Maghreb, identification keys, taxonomy, species list, sampling, specimen processing.
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BIANZO II: Biodiversity of three representative groups of the Antarctic Zoobenthos - Coping with Change. Final Report
- 1) SUMMARY a) Context The improvement of our understanding of ecological processes and the role of biodiversity in the Southern Ocean ecosystems remains a high priority on the research agenda in today’s changing world and is inextricably linked to sustainable development policies on a global scale. Global environmental changes influence species distributions and consequently the structure of communities and ecosystems. Only advances in our knowledge of the Southern Ocean biodiversity and processes important for ecosystem functioning can allow us to address complex evolutionary and ecological questions and enable estimations of the expected change of the biota distribution and composition. Polar regions experience greater rates of global change than any other region in the world. Their biota are highly adapted to the extreme environment they are living in and appear vulnerable to shifts in environmental conditions. Antarctic marine species are especially more sensitive to temperature variation as their physiology is set to a narrow range of temperatures. Also changes in food quality and quantity, together with other environmental shifts such as in pH of the seawater, are likely to impact densities, biomass and community composition but also functional aspects of the Antarctic biota. Because of the key-role of the Southern Ocean for the global ocean system and the growing impact of global environmental change, it is crucial to establish comprehensive baseline information on Antarctic marine biodiversity as a sound benchmark against which future change can be assessed reliably. It is equally important to understand better the ability of taxa to cope with changes in environmental parameters (temperature, pH, ice cover, food quantity and quality) linked to global change, and this from the individual to the community level. Imperative in this approach is to assess how structural and functional characteristics of the biota may be affected by a changing climate. Finally, advanced integrative spatial modelling of the distribution of key species in relation to environmental conditions is needed to predict the future of the marine ecosystems related to climate change. These aspects are addressed in the Bianzo II project by focusing on benthic organisms and communities, specifically representatives from three different size classes of the zoobenthos: Nematoda (meiobenthos), Amphipoda (macrobenthos) and Echinoidea (megabenthos). These three groups are characterised by a high diversity and many of the well over 4000 Antarctic benthic species described so far (Clarke & Johnston, 2003) belong to these taxa. These three selected benthic taxa are also ecologically important in terms of biomass, their role in biogeochemical cycles (C and N) and the trophic role they fulfil in the benthic ecosystem. Furthermore, they are characterised by different biogeographical and diversity patterns, speciation mechanisms, and reproductive and dispersal strategies. Because of these differences and the intrinsic ecological variability between these taxa, it is difficult to assess the extent to which global change will affect the Antarctic benthos in general. Rarely do biodiversity and ecological studies focus on multiple benthic groups. Yet, combining putative size groups in ecological/biodiversity research is imperative to understand the benthic ecosystem as a complex and interactive unity. b) Objectives Climate change and its complex and interactive chain of associated effects will affect the physiology, distribution, phenology, and ontogeny of many Antarctic benthic organisms, but the resulting changes from the species to the community level remain poorly quantified and understood. Individual species may appear vulnerable to environmental shifts or regime changes, but community and ecosystem responses may not act accordingly. Therefore we investigated the biodiversity and responses of the three representative groups of benthic organisms to climate change effects from individual species, over populations, up to the community level During its first phase (2007-2008), BIANZO II aimed at investigating (1) biodiversity patterns of the Antarctic zoobenthos and their causal processes by focussing on the three selected benthic groups (Work package 1: NOWBIO); Furthermore (2) trophodynamic aspects of each of the benthic groups, and their ability to cope with temperature and temperature-related changes (i.e. food composition and availability) but also the effect of pH of the seawater were on the benthos (Work package 2: DYNABIO). In the second phase (2009-2010) of the project, a joint review paper dealing with the effects of global climate change on the Antarctic zoobenthos is being written, based on the results of experiments, field results and literature data. Information collected in previous studies and in the first two work packages of this project was also used to develop a habitat suitability model in order to identify the drivers of benthic distribution patterns and forecast possible changes of benthic communities related to global change (Work package 3: FOREBIO). c) Conclusions i) NOWBIO (1) Benthic biodiversity in new ice free habitats Due to large-scale ice-shelf disintegration events, the Antarctic Larsen A and B areas along the Eastern Antarctic Peninsula recently became ice-free. Our study is the first one to investigate benthic communities and their response to the collapse of ice shelves in this area. At the time of sampling, meiofauna community structure at the inner stations, most remote from the original ice margin, was not or only slightly influenced by colonization, and might be structured by local environmental conditions. Communities living close to the former ice-shelf edge are believed to be at an intermediate or late stage of succession. Densities and diversity here were comparable to those at other more northern Antarctic stations in the Weddell Sea, whereas they were considerably lower at the inner stations. The three echinoid species collected in Larsen A&B areas are good candidates as pioneering species in a changing marine environment. They are known as indirect developers (or at least non-brooders), consistent with high dispersal capabilities. Moreover, this is congruent with the wide Antarctic distribution of these species. These examples stand in contrast to other Antarctic echinoids which are known as direct developers that brood their young and, accordingly, are supposed to present low dispersal capacities. The three Larsen species also display a ‘generalist’ feeding behaviour which can also be considered a characteristic of pioneering species. Furthermore, the symbiotic communities of echinoids in the Larsen area showed a low diversity and a strong similarity with epibionts present on stones, something which has not been observed in other regions so far. These results suggest that ectosymbioses linked to cidaroids could contribute to benthic colonization of the seafloor in these new ice free areas. The Larsen ice-shelf disintegration also led to the discovery of a low-activity methane seep. The observation of elevated densities, subsurface maxima and high dominance of one nematode species was similar to other cold-seep ecosystems world-wide and suggested a dependence on a chemosynthetic food source. However, stable 13C isotopic signals were indicative of phytoplankton-based feeding. This implied that the community was in transition from a chemosynthetic community to a classic phytodetritus feeding community, a temporary ecotone as it were. The characteristic parthenogenetic reproduction of the dominant species is rather unusual for marine nematodes and may be responsible for the successful colonisation by this single species.
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Origin and patterns of biodiversity of subterranean aquatic Clitellata
- Subterranean ecosystem biodiversity is characterized by a unique combination of four features that may account for its patterns and fluctuations at a global scale: (1) a low number of lineages due to environmental harshness, (2) a high proportion of endemic species as a result of habitat fragmentation and isolation, (3) a high level of relict taxa, best explained by the relative stability and antiquity of the habitat compared with most superficial habitats, and (4) food webs that are truncated at both the bottom (no primary producers) and the top (few or no predators and no specialized ones). In this review, we present a synthesis of the current state of knowledge of groundwater oligochaetes, and we investigate in what extent their biodiversity meets these criteria. The present knowledge is strongly biased in favour of the West-Palaearctic region, in particular the karst of Southern Europe. While our understanding of groundwater biodiversity in Europe and the United States has gained much during these last decades, many areas are undersampled in the world. To date, more than 300 nominal species have been found in ground waters all over the world (on about 1,700 and 1,100 aquatic and freshwater oligochaete species, respectively). Most of these species should be considered as incidentals or waifs; however, about one-third of them are found exclusively in this environment (stygobionts). Among the 21 families that are fully aquatic or include species occurring in aquatic habitats, 16 families are present in ground water. Stygobiont species belong to only 7 different families, harbouring 42 genera among which 17 are represented by a single species. Thirty-four per cent of the species are representatives of only two genera: Trichodrilus (Lumbriculidae) and Rhyacodrilus (Naididae). With 9 species, all being stygobiont, the Parvidrilidae is unique in being the only family, worldwide, comprising taxa that are restricted to groundwater habitats. Data on the distribution of stygobiont oligochaetes suggest pronounced endemism, nearly 60% of the species being known only from their type locality. The origins of subterranean oligochaete biodiversity probably involve multiple and successive colonization processes, both from marine and freshwater environments. The current distribution of Parvidrilidae, Rhyacodriloides (Rhyacodriloidinae), Delaya (Haplotaxidae), or species belonging to primarily marine genera, may be explained when assuming that these species are palaeoendemics or relicts, namely survivors of an old fauna that has long since become extinct in the surrounding areas. Aquatic oligochaetes appear to be pre-adapted to live in the subterranean environment. In the absence of genuine troglomorphic characters, their stygobiotic status can only be inferred from their exclusive presence in the subterranean environment. Valuable studies to enhance knowledge of subterranean aquatic oligochaetes will probably take more advantage of investigating adaptations that enable them to face scarceness of food and oxygen in groundwater, rather than focussing on an uncertain quest for morphological adaptations. Promising approaches would be to compare related hypogean and epigean species within the same genus, such as in Trichodrilus and Rhyacodrilus, or ecosystems the most similar to the underground such as lake hypolimnia and the deep sea. Keywords: ground water, Clitellata, biodiversity, patterns, endemism, relictuality, adaptation.
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Molecular and morphological evidence for the existence of several species with restricted range within the cosmopolite eurybathic deep-sea Lysianassoid amphipod Eurythenes gryllus sensu lato
- Introduction Eurythenes gryllus (Lichtenstein, 1822) is a presumed cosmopolitan eurybathic bentho-pelagic giant deep-sea amphipod. However, previous studies already highlighted genetically divergent lineages in the Atlantic and Pacific Oceans, which appeared to be vertically stratified, and minor morphological differences between populations were also recorded. Material and methods With an aim to quantify the geographic and bathymetric patterns of genetic variations, the genetic diversity in Eurythenes gryllus was investigated at the global scale (Arctic, Atlantic, Pacific and Southern Oceans) using three different genes (COI, 16S rRNA, 28S rRNA). This genetic analysis was followed by a thorough morphological study. Results Phylogenetic and phylogeographic analyses revealed the existence of at least seven well-supported clades, two bathyal and five abyssal, which were separated by genetic distances at the level of usual interspecific divergences. Furthermore, a clear genetic break was observed between specimens sampled above and below 3000 m. One clade comprised specimens from several bathyal sites in the Arctic and Southern Oceans. A subsequent morphological analysis confirmed the genetic findings and revealed small but consistent differences between the different clades, which will be described as separate species. Discussion This bathymetric break below 3000 m has already been reported for several organisms and regions, suggesting its role as a ubiquitous phylogeographic barrier for barophysical tolerance. The widely distributed Eurythenes clade, which is presumably the true E. gryllus, is, to our knowledge, the first molecular evidence for a bipolar distribution in a macro-benthic deep-sea organism. The present results clearly highlight the difficult nature of research on the systematics of deep-sea crustaceans and shows that the abyss is a more complex environment than previously assumed, which is likely to harbour an important hidden diversity.
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First report of the exotic blue planarian, Caenoplana coerulea (Platyhelminthes, Geoplanidae), on Menorca (Balearic Islands, Spain)
- In April 2009 two specimens of a terrestrial flatworm were collected from under a rock in an orchard at Ciutadella de Menorca on the easternmost Balearic island of Menorca (Spain). Their external morphology suggested that both specimens belonged to the invasive blue planarian Caenoplana coerulea, a species which is native to eastern Australia. Sequence data of a fragment of the mitochondrial cytochrome c oxidase subunit I (COI) and of the entire 18S ribosomal RNA confirm its identification. This is one of the first records of the species in Europe where it has only been found in one locality in the United Kingdom, France and NE Spain.
