Symbiosis

InBioS-Symbiosis tackles several research topics connected to symbiosis, from a single cell with its mitochondria and/or its chloroplasts of endosymbiotic origin (symbiogenesis) to large ecosystems where symbiotic interactions are key and active drivers of biodiversity:

1. Stability of the symbiotic interactions. We are interested by the co-evolution between the symbionts and their hosts. Such co-evolution was shown for permanent symbionts where the zygotes already include some symbionts from parent cells. In the case of endosymbioses involving protists, the partnership can become permanent and give rise to highly successful chimerical lineages. This raises the question of the beginnings of such world-changing associations, especially for chloroplasts.
2. Exchanges between partners. A successful symbiosis needs tight regulation of exchanges between symbiont and its host through diverse physiological and biochemical pathways beneficial for the holobiont. We study how environmental or stressful conditions can affect the physiology of each symbiotic partner and their contribution to balance the energy budget of the holobiont. We are specifically interested in understanding the diversity of photosynthetic regulatory mechanisms in microalgae, in bioenergetics and evolutionary perspectives.
3. Diversity between partners. Symbionts from different clades present physiological or ecological differences leading to different sensitivities to environmental constraints and associations with preferred hosts. Therefore, some symbiotic associations can be limited to specific environment while others present less restriction in their distribution. The study of these symbiotic associations allows a better understanding of the physiological capacities of each partner in various environments. At geological scales, phylogenomic approaches can help deciphering the complex network of associations at the origin of important chimerical lineages.
4. Dispersion and re-assembling the partnership. In several cases, such as between dinoflagellate and cnidarian, or between fungi and green algae or cyanobacteria, or both (lichens), the partners disperse either ‘alone’ or together. Separated partners must re-assemble and re-organize the physiological and ‘morphological-anatomical’ links of their symbiotic relationships; we examine how dispersal might be the driver of active evolution, incl. radiation and colonization of new habitats.