Existence, uniqueness and moment bounds for a spatial model of Muller's ratchet

Fuente: arXiv
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Autores principales: Madeira, João Luiz de Oliveira, Ortgiese, Marcel, Penington, Sarah
Formato: Preprint
Publicado: 2026
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author Madeira, João Luiz de Oliveira
Ortgiese, Marcel
Penington, Sarah
author_facet Madeira, João Luiz de Oliveira
Ortgiese, Marcel
Penington, Sarah
contents In this article, we consider a generalisation of the spatial Muller's ratchet introduced by Foutel-Rodier and Etheridge. This particle system is a spatial model of an asexual population, with birth and death rates that depend on the local population density. Particles live in discrete demes and migrate to neighbouring demes. Each particle carries some number of mutations (its `type'), and additional mutations can occur during birth events. Mutations are assumed to be deleterious, i.e.~carrying a higher number of mutations results in a lower birth rate. Our main result shows that this interacting particle system can be constructed even when the total initial number of particles is infinite. We also prove moment bounds on the local density of particles; these bounds are a crucial ingredient of the proof of a law of large numbers result for the particle system in the companion article. The construction of the particle system uses a sequence of approximating processes. Proving weak convergence of this sequence of processes is non-trivial because the particle system is non-monotone and interactions are non-local in type space. The uniqueness of the limit relies on a delicate coupling argument.
format Preprint
id arxiv_https___arxiv_org_abs_2603_06468
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Existence, uniqueness and moment bounds for a spatial model of Muller's ratchet
Madeira, João Luiz de Oliveira
Ortgiese, Marcel
Penington, Sarah
Probability
In this article, we consider a generalisation of the spatial Muller's ratchet introduced by Foutel-Rodier and Etheridge. This particle system is a spatial model of an asexual population, with birth and death rates that depend on the local population density. Particles live in discrete demes and migrate to neighbouring demes. Each particle carries some number of mutations (its `type'), and additional mutations can occur during birth events. Mutations are assumed to be deleterious, i.e.~carrying a higher number of mutations results in a lower birth rate. Our main result shows that this interacting particle system can be constructed even when the total initial number of particles is infinite. We also prove moment bounds on the local density of particles; these bounds are a crucial ingredient of the proof of a law of large numbers result for the particle system in the companion article. The construction of the particle system uses a sequence of approximating processes. Proving weak convergence of this sequence of processes is non-trivial because the particle system is non-monotone and interactions are non-local in type space. The uniqueness of the limit relies on a delicate coupling argument.
title Existence, uniqueness and moment bounds for a spatial model of Muller's ratchet
topic Probability
url https://arxiv.org/abs/2603.06468