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Main Authors: Hillairet, M, Mirrahimi, S
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2603.01983
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author Hillairet, M
Mirrahimi, S
author_facet Hillairet, M
Mirrahimi, S
contents We provide an asymptotic analysis of a nonlinear integro-differential equation which describes the evolutionary dynamics of a population which reproduces sexually and which is subject to selection and competition. The sexual reproduction is modeled via a nonlinear integral term, known as the Fisher's 'infinitesimal model'. We consider a small segregational variance regime, where a parameter in the infinitesimal model, which measures the deviation between the trait of the offspring and the mean parental trait, is small with respect to the selection variance. In this regime, we characterize the steady states of the problem and analyze their stability. Our method relies on a spectral analysis involving Hermite polynomials, highlighting the specific structure of the nonlinear reproduction term. We expect that the framework developed in this article will contribute to progress on several related problems that were out of reach with previous methods.
format Preprint
id arxiv_https___arxiv_org_abs_2603_01983
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Analysis of the steady solutions of the Fisher's infinitesimal model; a Hilbertian approach
Hillairet, M
Mirrahimi, S
Analysis of PDEs
We provide an asymptotic analysis of a nonlinear integro-differential equation which describes the evolutionary dynamics of a population which reproduces sexually and which is subject to selection and competition. The sexual reproduction is modeled via a nonlinear integral term, known as the Fisher's 'infinitesimal model'. We consider a small segregational variance regime, where a parameter in the infinitesimal model, which measures the deviation between the trait of the offspring and the mean parental trait, is small with respect to the selection variance. In this regime, we characterize the steady states of the problem and analyze their stability. Our method relies on a spectral analysis involving Hermite polynomials, highlighting the specific structure of the nonlinear reproduction term. We expect that the framework developed in this article will contribute to progress on several related problems that were out of reach with previous methods.
title Analysis of the steady solutions of the Fisher's infinitesimal model; a Hilbertian approach
topic Analysis of PDEs
url https://arxiv.org/abs/2603.01983