Institut de Systématique, Évolution, Biodiversité
ISYEB - UMR 7205/CNRS, MNHN, UPMC, EPHE,
Equipe Exploration, Espèces et Evolution
Muséum National d’Histoire Naturelle
57 Rue Cuvier, CP26
F-75005 Paris, France.
☏ : 33 (0)1 40 79 36 59
- Sarah Samadi
UMR 7205 ISyEB – Institut de Systématique, Evolution et Biodiversité
- Stéphane Hourdez
UMR 7144 - Adaptation et Diversité en Milieu Marin
2014 : Master Oceanography and Marine Environments (university Pierre et Marie Curie – Paris VI)
Internship : IFREMER (D. Zeppilli & M-A Cambon-Bonavita UMR 6197 LM2E)
Biodiversity of hydrothermal nematodes and associated prokaryotes.
Since its discovery in the late seventies, the fauna inhabiting hydrothermal vent has fascinated biologists. This habitat offers environmental conditions that are generally considered as “extreme” (darkness, huge range of temperature variations, sulfide or heavy metal toxicity, …). The very specific features of the organisms are generally interpreted as adaptations of the biological functions (such as nutrition, respiration or vision, etc…) to these extreme conditions.
Such interpretations are generally based on comparisons with poorly related organisms from the shallow-water fauna. However, to be considered as evolutionary adaptations, a robust phylogenic framework should be established. Indeed, the lack of resolution or an insufficient taxonomic sampling have lead to misinterpretation of the evolutionary significance of those features.
The aim of this thesis project is to establish for several flagship organisms inhabiting hydrothermal vents, a robust phylogenetic framework. This multi-taxa approach will provide new insights into the origin of the hydrothermal vent communities. In addition to available data for some flagship taxa (i.e. Bathymodiolinae, Siboglinidae) we will focus on several other families : the crustacea decapod families Alvinocarididae and Bythograeidae ; the mollusk gastropod familiy Provannidae ; and the worm annelid family Alvinellidae.
For each of these families, we will improve both the taxon-sampling and the sampling of molecular characters. For the former part, we will take advantage of the material gathered during recent cruises and of the important collections of the Muséum National d’Histoire Naturelle de Paris. For the later part, we will develop new DNA markers based on new sequencing methods (e.g. mitogenomics, exon-capture, etc…)
For the exon-capture approach, we first need to obtain transcriptomic data in order to define a set of orthologous exons within each targeted taxon. For this first step we will select about ten species covering at best the known lineages within the infraorder or superfamily in which each of the selected families is included. The transcriptomic analysis will allow us to determine and select orthologous markers. We will then design probes permitting the hybridization-capture of targeted sequences over a wider taxonomic coverage. We should then be able to infer the phylogenetic relationships among vent and non-vent species. This approach should allow us to determine if colonization of hydrothermal environments happened once or more. In the latter case, the specific features of vent organisms would result from convergence. The comparison of the results among the different flagship organisms should allow us to determine if the colonization events are correlated and thus to give new insights into the origin of vent communities.