RESEARCH
Changing environments
Predicting how microbial communities respond to environmental change is crucial for managing their function in the face of changing climate, health, and disease. Yet these communities’ enormous diversity and complexity makes predicting their dynamics seemingly intractable.
We combine tractable systems in the laboratory with simple mathematical models to discover unifying rules of microbial communities. We showed that increasing mortality favors fast-growing species, and that increasing temperature favors slow-growing species. We then validated our laboratory results in global ocean datasets, finding that slower-growing bacterial species are more abundant in warmer seawater—during summer, at the surface, or near the tropics.
We also study how environmental fluctuations affect the predictability of ecological and evolutionary trajectories. We found that simple ecological communities can be predictable, while more diverse communities may undergo more change. In evolving populations of yeast, we found that fluctuations dramatically alter fitness of adaptive mutations through enviromental memory.
Eco-evolutionary dynamics
We often assume that ecology takes place in the short term, as multiple species interact and assemble into communities. In the long term, we think of evolution slowly changing a species as mutations arise and spread, altering its fitness and interactions with other species.
But a separation between ecology and evolution is an over-simplification. In microbes particularly, large population sizes cause eco-evolutionary dynamics to unfold rapidly. Mutations spread as species form communities, changing their interactions and community structure.
What's more, genotypic diversity in natural microbial populations is thought to arise from interactions between strains of the same species, driving micro-evolution. To understand and predict these dynamics, we are using a library of barcoded yeast mutants generated from our previous study. We will compare theoretical predictions about how strains affect each other's evolution to ideas like character displacement, which hypothesizes that species specialize to avoid competing.
Competition vs. cooperation
The fields of ecology and evolution have focused primarily on competition, rather than on cooperation. Despite ample evidence of cooperation in nature, simple mathematical models assume competitive interactions, which has likely led to confirmation bias in microbial experiments. Similarly, despite the staggering diversity of natural microbial communities, equilibration in the lab results in communities of very few species.
Recent theoretical work has speculated that cooperative interactions might support greater biodiversity. We will investigate evolution of cooperation by adding mutualistic partners to our experiments that cross-feed with yeast. This system will allow us to investigate whether positive cross-feeding interactions support evolution of biodiversity.
publications
Abreu, C. I., Mathur, S., & Petrov, D. A. (2024). Environmental memory alters the fitness effects of adaptive mutations in fluctuating environments. Nature Ecology & Evolution, 1-16. (Link) (shareable PDF)
Abreu, C. I.*, Dal Bello, M.*, Bunse, C., Pinhassi, J., & Gore, J. (2023). Warmer temperatures favor slower-growing bacteria in natural marine communities. Science Advances, 9(19), eade8352. (Link)
Mancuso, C. P., Lee, H., Abreu, C. I., Gore, J., & Khalil, A. S. (2021). Environmental fluctuations reshape an unexpected diversity-disturbance relationship in a microbial community. Elife, 10, e67175. (Link)
Abreu, C. I., & Datta, M. S. (2021). When two are better than one. Nature Ecology & Evolution, 5(9), 1199-1200. (Link)
Abreu, C. I.*, Andersen Woltz, V. L.*, Friedman, J., & Gore, J. (2020). Microbial communities display alternative stable states in a fluctuating environment. PLOS Computational Biology, 16(5), e1007934 (Link)
Lax, S.*, Abreu, C. I.*, & Gore, J. (2020). Higher temperatures generically favour slower-growing bacterial species in multispecies communities. Nature Ecology & Evolution, 1-8. (Link)
Abreu, C. I., Friedman, J., Andersen Woltz, V. L., & Gore, J. (2019). Mortality causes universal changes in microbial community composition. Nature communications, 10(1), 2120. (Link)
Abreu, C. I., Ortiz Lopez, A., & Gore, J. (2018). Pairing off: a bottom‐up approach to the human gut microbiome. Molecular systems biology, 14(6), e8425. (Link)