Léa COMBES

Diversity and metabolic adaptation of lacustrine microbial eukaryotes in response to global change: an insight into parasites
 

Environmental disturbances, whether natural or anthropogenic, are major drivers of the dynamics and evolution of microbial communities. Aquatic ecosystems are not spared and are subject to increasing pressures, such as rising temperatures, eutrophication, and the spatial and temporal expansion of oxygen-depleted zones, all of which can impact the structure and functions of microbial communities. Despite the central role of microorganisms in ecological processes, their responses to these disturbances remain poorly understood.

My doctoral project aims to explore the spatio-temporal dynamics, both short- and long-term, as well as the mechanisms of metabolic adaptation of unicellular eukaryotes in lakes in response to these changes. Particular attention is given to parasitic groups, whose ecological importance is increasingly recognized, notably microsporidia, which have recently been revealed to be highly diverse in aquatic ecosystems, as well as other parasites affiliated with fungi.

Several complementary approaches will be implemented using samples from a model lake (Aydat):

(1) an analysis of past community diversity through a paleogenomic approach, which will allow us to decipher their dynamics in relation to the Anthropocene (from approximately 1950 onwards);

(2) high-resolution spatio-temporal monitoring of the water column (every meter, every two weeks for one year), which will highlight seasonal and vertical variations;

(3) a microcosm approach to assess the impact of intensified anoxic conditions, temperature, and eutrophication on community structure and function;

(4) metatranscriptomic analyses to decipher the metabolic and adaptive strategies of the main groups identified.