My PhD project aims to provide some answers on the evolutionary stability of mutualistic symbioses. It aims to test the hypotheses of « fidelity of partners » and « host sanction » in the subterranean termites Reticulitermes grassei and R. flavipes (Rhinotermitidae). Termites are wood-feeding social insects that depend of gut microorganisms to degrade lignocellulose (Brune 2014). Living the hindgut (the « paunch »), these microorganisms constitute very diverse communities composed by numerous prokaryotes (bacteria and archeae) and eukaryote protists.
The first objective of this project is to study if all taxa of these microorganisms are vertically transmitted to next generation, and otherwise what are the bottlenecks (imaginal molt, bad season)?
The second objective is to identify host genes (immunity genes?) that are potentially implicated in the maintenance of the composition of microbial community testing gene expression patterns in nymphs in which the microbial community will have been experimentally modified.
These experiments will allow (i) to estimate the efficiency of symbionts transmission through generations, and (ii) to identify host genes (immunity?) that are potentially involved in the regulation of microbial community. This project will allow us to better understand the mechanisms involved in the evolutionary stability of mutualistic symbioses in termites.
Michaud C., Chupeau C., Bech N., Thierry M., Sicard M., Grève P., Beltran-Bech S. (2016). Isolation, characterization and PCR multiplexing of microsatellite loci for two sub-species of terrestrial isopod Porcellio dilatatus (Crustacea, Oniscidea). Genetica, 144:223-228.