PT  - JOURNAL ARTICLE
AU  - Madec, Sten
AU  - Gjini, Erida
TI  - Co-colonization interactions drive explicit frequency-dependent dynamics among <em>N</em> types
AID  - 10.1101/722587
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 722587
4099  - http://biorxiv.org/content/early/2019/08/02/722587.short
4100  - http://biorxiv.org/content/early/2019/08/02/722587.full
AB  - A fundamental question in ecology is the generation and maintenance of biodiversity. Classical approaches consider multi-species communities with Lotka-Volterra ODE models where inter- vs. intra-species interactions are key. Typically in high-dimensional systems, analysis is hard and model reduction is needed. Here, we describe and study a new system of multi-type interactions that arise in co-colonization, and develop a useful model reduction framework based on slow-fast dynamics under quasi-neutrality. We show that in a multi-type, Susceptible-Infected-Susceptible (SIS) system with co-colonization, neutral coexistence dynamics between N closely related strains occurs on a fast timescale, based on mean trait values, whereas the non-neutral selective forces act on a slow timescale, driven by the variance and asymmetries of the co-colonization interaction matrix. The explicit N equations for relative type frequencies on the slow manifold enable efficient computation of complex multi-strain dynamics, and provide analytical insight into high-dimensional community ecology, with potential applications to other multi-body systems.