Speaker
Description
Determining whether a new species can invade an established microbial community is a central problem in ecology and evolution. We develop a replicator-dynamics framework that links invasion outcomes to microbiome composition through frequency-dependent interactions between species \cite{3,4}.
In this formulation, the initial growth of an invader has two components: interactions between the invader and resident species, and the system’s intrinsic resistance to invasion generated by interactions between species already present. Both contributions arise from pairwise interaction terms and together determine whether invasion succeeds.
We illustrate this framework in two microbiome systems. First, we analyze experiments where antibiotic-resistant and wild-type \textit{E. coli} strains co-invade mouse gut microbiota \cite{1}. Using this approach, we infer how community composition modulates the selection coefficient between the two invaders.
Second, we apply the framework to vaginal microbiome data from a large cohort by mapping Nugent scores (an indicator of vaginal health) to invader growth rates, allowing us to quantify community susceptibility to pathogenic invasion \cite{2}. The resulting model predicts vaginal health states with accuracy comparable to machine-learning approaches while providing a mechanistic ecological interpretation.
More broadly, this work illustrates how replicator dynamics can be used to study invasion processes in complex microbial communities.
Bibliography
@article{1,
title = {Unpacking fitness differences between two invaders in a multispecies context},
volume = {87},
ISSN = {1522-9602},
url = {http://dx.doi.org/10.1007/s11538-025-01491-5},
DOI = {10.1007/s11538-025-01491-5},
number = {9},
journal = {Bulletin of Mathematical Biology},
publisher = {Springer Science and Business Media LLC},
author = {Ferreira Amaro Freire, Tomas and Madec, Sten and Gjini, Erida},
year = {2025},
month = jul
}
@article{2,
title = {Modeling the human vaginal microbiome and its protection against pathogens using the replicator framework for invasion},
url = {http://dx.doi.org/10.64898/2026.02.20.707042},
DOI = {10.64898/2026.02.20.707042},
publisher = {openRxiv},
author = {Freire, Tomás Ferreira Amaro and Garcia-Romero, Marina and Gjini, Erida},
year = {2026},
month = feb
}
@article{3,
title = {Predicting N-Strain Coexistence from Co-colonization Interactions: Epidemiology Meets Ecology and the Replicator Equation},
volume = {82},
ISSN = {1522-9602},
url = {http://dx.doi.org/10.1007/s11538-020-00816-w},
DOI = {10.1007/s11538-020-00816-w},
number = {11},
journal = {Bulletin of Mathematical Biology},
publisher = {Springer Science and Business Media LLC},
author = {Madec, Sten and Gjini, Erida},
year = {2020},
month = oct
}
@article{4,
title = {Towards a mathematical understanding of invasion resistance in multispecies communities},
volume = {10},
ISSN = {2054-5703},
url = {http://dx.doi.org/10.1098/rsos.231034},
DOI = {10.1098/rsos.231034},
number = {11},
journal = {Royal Society Open Science},
publisher = {The Royal Society},
author = {Gjini, Erida and Madec, Sten},
year = {2023},
month = nov
}
