L’histoire évolutive de complexes d’espèces proches est souvent difficile à reconstruire à cause d’un manque de données informatives. Les données RADseq (Restriction site-associated DNA sequencing) permettent de collecter une grande quantité de données ADN, y compris pour des organismes non-modèles. Ici nous avons utilisé les données RADseq pour étudier le complexe d’espèces d’escargots terrestres du genre Pyramidula. La concaténation des séquences ADN obtenues (environ 1,5 x 106 caractères et >97 x 103 sites polymorphiques) a permis de reconstruire les relations phylogénétiques entre les espèces du complexe avec beaucoup plus de résolution que si des marqueurs phylogénétiques standards avaient été utilisés (COI, 16S rARN, 5.8S rARN, ITS2 and 28S rARN). D’autre part, l’analyse de 875 SNPs (single-nucleotide polymorphisms) et de plusieurs scénarios de délimitation d’espèces a soutenu l’hypothèse que neuf espèces de Pyramidula étaient à distinguer au sein de notre échantillonnage. Enfin, l’analyse de la répartition des allèles parmi les individus séquencés (D-statistics) n’a pas montré d’évidence d’hybridation interspécifique ancestrale, si ce n’est entre deux espèces, P. pusilla and P. saxatilis.
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RBINS Staff Publications 2016
Within the historic center of Brussels, excavations on a surface of almost 6000 m2 revealed the well preserved remains of a medieval port on the Senne river. This watercourse is inextricably linked with the origin and development of the city. Continuous occupancy at this location is documented from the 10th century onwards. The banks of the river were gradually built in the 12th century and in the 14th-15th century the river was canalised and provided with a boat dock. The Senne river played an important role in the local social and economic development of Brussels. A large amount of archaeological artefacts, including numerous animal remains, have been collected by hand and from sediment samples taken from the east bank and the riverbed. Preliminary results show how the Senne river acted as a waste bin for urban rubbish. This poster will mainly focus on the animal materials from the residues of the sieved sediment samples. These yielded many shells of local freshwater molluscs, which are informative for the river conditions. In addition, the protective cases of the larvae of caddisflies (Trichoptera) have been found. Caddisflies are a group of insects with aquatic larvae and terrestrial adults. The larvae of many species use silk to make protective cases, which are often strengthened with gravel, sand, twigs, plant fragments or other debris. While the cases of many of these species are not identifiable up to genus or species level, the presence of Brachycentrus subnubilus Curtis, 1834 has been established with certainty in the late medieval riverbed of the Senne. The importance of this find is discussed.
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RBINS Staff Publications 2023
