This postdoc title is: 'Tracking the evolution and ageing of ‘evosystems’ through network-modelling of the dynamics of ecosystems shaped by selection on differential persistence'.

More specifically, in collaboration with Fabrice Not, on the evolution and ageing of ecosystems, the postdoctoral fellow, skilled in bioinformatics, with an interest for evolution, ecology, networks and possibly philosophy of sciences, will construct and analyse multilayer networks that approximate the dynamics of interactions within ecosystems, based on -omics time-series, to quantify what we would call an 'ecosystemic fitness' using original network metrics.

One the key idea of the project is to track whether networks gain or lose in 'persistence fitness', e.g. robustness or resilience with time, and under what conditions one might consider parts of ecosystems as 'units of selection' that might be sensitive to various changes in selective pressures, and therefore evolve and age.

 

Indeed, with environmental changes, better modelling and predicting natural ecosystems dynamics is critical from an ecological and a societal viewpoint. Ecosystems are defined as interconnected, diverse biological communities embedded in an abiotic compartment, connected to other ecosystems by spatial flows of energy, materials and information. Ecosystems are traditionally studied by ecologists, who seek causal relationships between environmental conditions and ecosystemic properties, e.g. between ecosystem stability and species richness. By contrast, this project introduces an original network-based approach to import evolutionary-thinking into ecosystem studies, with potential to make new paradigms about ecosystem dynamics emerge. Due to direct and indirect interactions between resident and migrating lineages evolving in ecosystems, ecosystems present local and, sometimes, global homeostasis-like properties: stability, cyclicity and resilience, evoking ‘ecosystem phenotypes’. In organisms, such homeostatic properties are often considered as adaptative, derived from natural selection. In this project, we will hold that it can be scientifically fruitful to consider that, to some extent, like organisms, ecosystems evolve, i.e. selection acting at the level of ecosystems may explain some of their homeostatic properties.

 

The overarching goal of this project is to support our proposed unifying concept of ‘evosystems’ by providing evidence for natural ecosystems evolution and to assess ecosystem fitness. Evosystems correspond to ‘ecosystems phenotypes’ that behave as if they evolved by selection, and could further evolve due to evolutionary constraints. Typically, evosystems could become maladapted, when selective pressures acting at the level of ecosystem change, or evosystems could age, when selective pressures supporting an ecosystem robustness/resilience weakens with time. To achieve its goal, this project will take advantage of recent progresses in environmental -omics approaches that offer a holistic perspective on critical, under-appreciated sources of “ecosystem homeostatic properties”: microbial interactions, and of multilayer network studies, because homeostasis-like properties emerge from interaction networks whose degree and
patterns of connectivity critically shape ecosystem dynamics. On a theoretical level, this project will deeply integrate ecological, evolutionary and philosophical perspectives, and provide original tools to track natural ecosystem fitness, enhancing the toolbox of ecosystem monitoring.