In the last years, we have developed and studied an N-strain SIS system with co-colonization and strain interactions, leading to a replicator equation [4]. Applying slow-fast dynamics, we have simplified this high-dimensional eco-epidemiological system, finding parallels between microbial transmission at the population level and also multi-species microbiota dynamics within host. In this talk, I will describe 2 ways to link our replicator model to data: i) in an epidemiological context [3] and ii) in a microbiological [1] context. First, we apply the framework of replicator dynamics to 5 datasets of Streptococcus pneumoniae serotype frequencies in different countries. We estimate pairwise strain interactions from population-level frequencies across different endemic settings (Mozambique, Brazil, Denmark, Nepal and Iran), linking mechanistically their distributions [3]. In another work, at a different biological scale, we link ecological invasion dynamics to our explicit replicator equation model [2, 4], and extract key fitness difference parameters between two invaders in a multispecies host. This enables us to predict their initial selection dynamics, and its uncertainty in other contexts. The method is illustrated on invasion data from E.coli strains in mice with different microbiota [1], but is applicable to other microbiota and co-invasion scenarios. Overall our work opens new perspectives on uses and insights coming from the replicator equation on biological data.

References

[1] Tomas Ferreira Amaro Freire, Sten Madec, and Erida Gjini. Unpacking fitness differences between two invaders in a multispecies context. bioRxiv, pages 2024-11, 2024.

[2] Erida Gjini and Sten Madec. Towards a mathematical understanding of invasion resistance in multispecies communities. R. Soc. Open Sci., 10:231034, 2023.

[3] Thi Minh Thao Le, Sten Madec, and Erida Gjini. Nested inference of pairwise interactions from strain frequency data across settings and context-dependent mutual invasibilities. bioRxiv, pages 2024-09, 2024.

[4] S. Madec and E. Gjini. Predicting N-strain coexistence from co-colonization interactions: Epidemiology meets ecology and the replicator equation. Bulletin of Mathematical Biology, 82:142, 2020.