28 février Laure Schneider-Maunoury, ISYEB
Ecology and reproduction biology of the black truffle Tuber melanosporum
The black truffle Tuber melanosporum – the “black diamond” of French gastronomy – is an ascomycete fungus living in mycorrhizal symbiosis with tree roots. Few things are known about the ecology and biology of this iconic mushroom. The black truffle is potentially hermaphroditic but reproduction and formation of the edible organ, the ascocarp, require mating between individuals from opposite mating type : a maternal parent that forms the ascocarp flesh and a paternal one whose genes are only left in the meiotic spores within the ascocarp. Maternal genotypes are also found on the surrounding mycorrhizae, suggesting that maternal partners are established as symbiont on the host trees. In contrast, paternal genotypes are never found in mycorrhizae, and are more numerous and transient than maternal genotypes. Several questions arise therefore : what are the paternal partners (mycelium, spores...) and where do they come from ? We conducted population genetics studies using microstallites which revealed a high level of inbreeding, raising the question of the existence of gametic gene flow. Another mysterious aspect of T. melanosporum ecology is the presence of an area at the base of the host trees characterized by few herbaceous species, called a brûlé. Not a lot is known about causes or consequences of the brûlé, but it has been shown recently that, unexpectedly, T. melanosporum may be detected molecularly and genotyped within the roots of the herbaceous plants. We now want to elucidate what kind of interaction is involved in this particular niche and whether paternal partners could be there.
7 mars François Michel, chercheur à l’Institut de Biologie Intégrative de la Cellule (I2BC, CNRS), Gif-sur-Yvette
Hérédité d’une incompatibilité physiologique récurrente dans des croisements interspécifiques de lépidoptères / A recurrent pattern of physiological incompatibility in interspecific butterfly crosses
Traditional views of species formation, which hold that physiological incompatibilities linked to ecological divergence are the primary cause of speciation, predict recurrent themes of hybrid inviability for any particular lineage. Lepidoptera provide an opportunity to test these ideas, since provoked mating (‘hand-pairing’) makes it possible to investigate in a systematic manner the developmental problems that affect the progeny of interspecific crosses. One common source of interspecific incompatibility in these insects is the inability of F1 hybrids either to enter diapause or to resume development when in a diapausing state. By taking examples from experiments I carried out on members of two butterfly families, I will show that analysis of diapause-connected phenotypes in hybrid offspring allows one to order indvidual species along a quantitative scale, from which it is possible to ‘predict’ their propensity to skip diapause in natural settings. As hybrids between these closely related species tend to be fertile, at least in backcrosses, and were found to pass on their imbalances to part of their offspring, it should be straightforward nowadays to identify the genes involved in the breakdown of diapause regulation. Tracking the alleles of those genes at locations at which introgression has been shown to occur could then be used to probe their role in speciation.
14 mars Aurelie Khimoun, ISYEB, equipe BIPEM.
Landscape structure influences within-island gene flow in a forest specialist bird species
21 mars Eric Dugat-Bony, Chargé de Recherche INRA, UMR782 GMPA
4 avril : Pas de séminaire
11 avril : Pas de séminaire
13 juin Vyacheslav Yurchenko, Associate Professor and Lab Head,
Laboratory of Molecular Protozoology, University of Ostrava, Czech Republic
Trypanosomatids in the Next-Gen Sequencing era