Dispersal barriers and functional convergence in aquatic microorganisms

Dispersal limitation (i.e. the fact that a species may not be able to reach an otherwise suitable habitat) has been recognized as a major driver of biogeographical patterns and evolutionary dynamics.

Microorganisms, however, are so abundant and disperse so easily that it is often though that they are unnafected by dispesal limitation.

For almost a century, the prevailing view has been summarized by the famous hypothesis by Baas Becking that “everything is everywhere, but the environment selects”.

This view has been recently challenged by several authors, but results have been contradictory, spanning a debate that so far remains open.In this project, I will use state of the art techniques to study the core and accessory gene dynamics of hundreds of bacterial and archaeal species over thousands of lake samples from five continents, and assess the extent and mechanisms of dispersal limitation in aquatic microorganisms.

This will produce for the first time a global intra-species level biogeography for freshwater microbial species.

I will also address whether accessory genes are coupled to core genomes, or if they can flow freely to produce different strains with similar functions and ecological roles.

By combining for the first time the concepts of dispersal limitation and intra-species functional redundancy at a global scale, this project will bring new perspectives to microbial biogeography and ecology, and help solve several outstanding controversies in the field.