Unravelling the determinants of microbial community diversity
My latest project at MIT aims at disentangling the relationship between resource availability and microbial community diversity.
Although photosynthetic bacteria are among the most abundant organisms on Earth, many microbial communities, including those living in the human gut and in the soil, rely on externally supplied carbon sources to survive and thrive. A major question is thus: do larger numbers of available resources mean more coexisting species? This is still largely unresolved because, traditionally, different facets of resource availability have been tackled separately, with theory focusing on the effects of the number of resources on species coexistence, and experiments concentrating on the impact of resource identity on community composition and function.
To fill this gap, I studied the assembly of hundreds of soil-derived microbial communities on a wide range of well-defined resource environments, from single carbon sources to combinations of up to 16. We found a remarkable diversity in single resources but a linear one-by-one increase in the number of species with the number of additional resources. We reconciled these apparently contrasting observations by looking at the distribution of resource generalists and specialists in the experimental communities. We showed, both experimentally and with a model, that both observations originated from generalist and specialist species interacting in a modular fashion within the community. I am particularly excited about this project because, given the ubiquitous presence of generalist and specialist species in natural microbiomes, these results might apply to a variety of different ecological settings, providing a framework to predict how microbial diversity responds to changes in resource availability.
You can read the full story here.