Emergent behaviors in complex microbial ecosystems

Date: 2023/11/29 - 2023/11/29

Academic Seminar: Emergent behaviors in complex microbial ecosystems

Speaker: Jiliang Hu,PhD, Prof. Jeff Gore’s Group, Department of Physics, Massachusetts Institute of Technology

Time: 16:00 - 17:30, November 29, 2023 (Beijing Time)

Location: CIMC Auditorium (Room 300), JI Long Bin Building


From tropical forests to gut microbiomes, ecological communities harbor diverse and abundant species. Understanding the complex emergent phenomena of diversity, stability, and invasibility in these communities within a unified framework has been a significant challenge. We address this knowledge gap by conducting the first direct test of a theory proposing that simple community-level features govern emergent behaviors. By utilizing bacterial microcosms, we demonstrate that as the number of species or the strength of interactions increases, microbial ecosystems transition through three distinct dynamical phases: from stable coexistence, to partial coexistence, to the emergence of persistent fluctuations and alternative stable states in species abundances, confirming theoretical predictions. Notably, high biodiversity and dynamic fluctuations reinforce each other under fixed conditions. By combining theoretical frameworks and microbial community experiments, we establish that community-level features determine the invasion outcome in microbial communities. We found that the communities with fluctuations in species abundance are more invasible and diverse than stable ones, leading to a positive diversity-invasibility relationship. As predicted by theory, increasing interspecies interaction strength and size of species pool leads to a decrease of invasion probability in our experiment. Although diversity-invasibility relationships are qualitatively different depending upon how the diversity is changed, we resolved the diversity-invasibility debate by showing a universal positive correspondence between invasibility and survival fraction across all conditions. Communities composed of strongly interacting species can exhibit an emergent priority effect in which invader species are less likely to colonize than species in the original pool. However, in this regime of strong interspecies interactions, if an invasion is successful it causes larger ecological effects on the resident community than when interactions are weak. Overall, my work uncovers predictable emergent patterns of diversity, dynamics, and invasibility in ecological communities, offering insights into a unified framework for microbial ecology.


Jiliang Hu got his PhD in the lab of Jeff Gore at MIT, where he is studying emergent behaviors of complex microbial communities by bridging theory and experiment. He is broadly interested in unveiling coarse-grained features that can dictate complex spatial temporal patterns in multicellular systems. Jiliang received his BS in Mechanics from Tsinghua University in 2017.