How seed banks evolve in plants: a stochastic dynamical system subject to a strong drift

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Hauptverfasser: Etheridge, Alison, Madeira, João Luiz de Oliveira
Format: Preprint
Veröffentlicht: 2026
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author Etheridge, Alison
Madeira, João Luiz de Oliveira
author_facet Etheridge, Alison
Madeira, João Luiz de Oliveira
contents We study how changes in population size and fluctuating environmental conditions influence the establishment of seed banks in plants. Our model is a modification of the Wright-Fisher model with seed bank, introduced by Kaj, Krone and Lascoux. We distinguish between wild type individuals, producing only nondormant seeds, and mutants, producing seeds with dormancy. To understand how changing population size shapes the establishment of seed banks, we analyse the process under a diffusive scaling. The results support the biological insight that seed banks are favoured in a declining population, and disfavoured if population size is constant or increasing. The surprise is that this is true even when population sizes are changing very slowly -- over evolutionary timescales. We also investigate the influence of short-term fluctuations, such as annual variations in rainfall or temperature. Mathematically, our analysis reduces to a stochastic dynamical system forced onto a manifold by a large drift, which converges under scaling to a diffusion on the manifold. Inspired by the Lyapunov--Schmidt reduction, we derive an explicit formula for the limiting diffusion coefficients by projecting the system onto its linear counterpart. This provides a general framework for deriving diffusion approximations in models with strong drift and nonlinear constraints.
format Preprint
id arxiv_https___arxiv_org_abs_2602_04437
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle How seed banks evolve in plants: a stochastic dynamical system subject to a strong drift
Etheridge, Alison
Madeira, João Luiz de Oliveira
Probability
Dynamical Systems
Populations and Evolution
We study how changes in population size and fluctuating environmental conditions influence the establishment of seed banks in plants. Our model is a modification of the Wright-Fisher model with seed bank, introduced by Kaj, Krone and Lascoux. We distinguish between wild type individuals, producing only nondormant seeds, and mutants, producing seeds with dormancy. To understand how changing population size shapes the establishment of seed banks, we analyse the process under a diffusive scaling. The results support the biological insight that seed banks are favoured in a declining population, and disfavoured if population size is constant or increasing. The surprise is that this is true even when population sizes are changing very slowly -- over evolutionary timescales. We also investigate the influence of short-term fluctuations, such as annual variations in rainfall or temperature. Mathematically, our analysis reduces to a stochastic dynamical system forced onto a manifold by a large drift, which converges under scaling to a diffusion on the manifold. Inspired by the Lyapunov--Schmidt reduction, we derive an explicit formula for the limiting diffusion coefficients by projecting the system onto its linear counterpart. This provides a general framework for deriving diffusion approximations in models with strong drift and nonlinear constraints.
title How seed banks evolve in plants: a stochastic dynamical system subject to a strong drift
topic Probability
Dynamical Systems
Populations and Evolution
url https://arxiv.org/abs/2602.04437