Workshop of the ERC project MUSEUM : MUlti- Scale Eco-Evolutionary population dynaMics

7 janv. 2026, 13:30 → 9 janv. 2026, 12:30 Europe/Paris

bâtiment 9, Salle 109 (Institut Montpelliérain Alexander Grothendieck)

This workshop brings together mathematicians specializing in mathematical modeling, PDE theory, and probability theory, and biologists specializing in evolutionary biology, to discuss problems, methods, and results related to the topics of the ERC project MUSEUM. This project is interested in the asymptotic analysis of multi-scale integro-differential equations and stochastic individual-based models arising in evolution biology. Three main research directions will be discussed:

• analysis of the infinitesimal model of sexual reproduction, impact of the sexual reproduction on the adaptation of populations

• link between stochastic individual-based models and Hamilton-Jacobi equations, impact of demographic stochasticity on the adaptation of populations

• adaptation of complex traits, such as age-dependent traits in pathogens or size-dependent traits in plants

 

The workshop will begin in the early afternoon of January 7th and conclude around noon on January 9th.

Organizing committee :

Matthieu Hillairet
Sepideh Mirrahimi

mer. 7 janvier

14:00 → 14:45 Genetic and demographic constraints on adaptation: insights from Integro-projection models and research challenges

The concept of evolutionary potential is central to many questions in evolutionary biology and key in particular to our understanding of adaptation prospects to ongoing global changes.  I will illustrate  how understanding limits to adaptation necessitates to integrate together genetic and demographic constraints. I will deal with structured heterogeneous populations, where different individuals make different contributions to the demography and evolution of the population, because they belong to different stages in the life cycle, have a different age  and size, affecting their growth, fecundity and survival. We use 30 years of demographic surveys in the endangered highly endemic plant Centaurea corymbosa to predict under which conditions boosting the genetic diversity  through assisted gene flow could rescue the small declining populations from short-term extinction in an already too warm climate. Through this example, I will introduce Integro-Projection Models, which have become extremely popular in population dynamics studies in recent years, but are the subject of controversies about how evolution is integrated. These Integro-Projection models, which emerged from empirical research, have been explored exclusively numerically and are potentially an area of research where greater mathematical insight could lead to some breakthrough in their validation and use.

Orateur: Ophélie Ronce (Institut des sciences de l'évolution-Montpellier)

14:45 → 15:30 Exposé

Orateur: Jessica Guerand (Institut Montpelliérain Alexander Grothendieck)

15:30 → 16:00 Pause café

16:00 → 16:45 Niche construction as an emerging phenomenon between fast ecological and slow evolutionary timescales in individual-based models

The concept of evolutionary potential is central to many questions in evolutionary biology and key in particular to our understanding of adaptation prospects to ongoing global changes.  I will illustrate  how understanding limits to adaptation necessitates to integrate together genetic and demographic constraints. I will deal with structured heterogeneous populations, where different individuals make different contributions to the demography and evolution of the population, because they belong to different stages in the life cycle, have a different age  and size, affecting their growth, fecundity and survival. We use 30 years of demographic surveys in the endangered highly endemic plant Centaurea corymbosa to predict under which conditions boosting the genetic diversity  through assisted gene flow could rescue the small declining populations from short-term extinction in an already too warm climate. Through this example, I will introduce Integro-Projection Models, which have become extremely popular in population dynamics studies in recent years, but are the subject of controversies about how evolution is integrated. These Integro-Projection models, which emerged from empirical research, have been explored exclusively numerically and are potentially an area of research where greater mathematical insight could lead to some breakthrough in their validation and use.

Orateur: Nicolas Champagnat (Inria Nancy)

16:45 → 17:30 Exposé

Orateur: Pascal Maillard (Institut de mathématiques de Toulouse)

jeu. 8 janvier

09:15 → 10:00 Exposé

Orateur: Sylvain Gandon (Centre d'écologie fonctionnelle et évolutive-Montpellier)

10:00 → 10:30 Pause café

10:30 → 11:15 Exposé

Orateur: Viet Chi Tran (Inria Lille)

11:15 → 12:00 Concentration in selection-mutation models: error estimates and asymptotic expansions

n this presentation we study an integro-differential equation which describes the evolutionary dynamics of a population structured by a phenotypic trait. This population undergoes asexual reproduction, competition, selection, and mutation. We provide an asymptotic analysis of the model, assuming that the mutations have small effects.  A standard approach for the analysis of the qualitative properties of the solutions of such an equation is to apply a logarithmic transformation, which yields a Hamilton–Jacobi equation with constraint. When the reproduction term is a concave function of the trait, it has been established that the solution is classical. We rigorously derive a first-order asymptotic expansion of the solution. This expansion allows us to approximate the moments of the phenotypic density. This result establishes a connection between the approximations of the phenotypic density obtained via the Hamilton-Jacobi approach and relevant biological quantities, which are more suitable from a modeling perspective. This is a joint work with my PhD advisors, Sepideh Mirrahimi and Jean-Michel Roquejoffre.

Orateur: Caroline Guinet (Institut de mathématiques de Toulouse)

12:00 → 14:00 Buffet

14:00 → 14:45 Temps libre - discussions

14:45 → 15:30 Evolution of the (co)variances of quantitative traits in stage-structured populations.

The speed of evolution of a phenotypic trait increases with the proportion of its variation that is transmitted to the next generation. The genetic variance for the trait is thus considered a good measure of evolutionary potential. The former can be computed from the joint distribution of the different gene copies that determine the trait value in the population. Evolutionary forces such as genetic drift, selection, recombination, mutation, and migration shape these distributions and thus the evolution of genetic variance. Many theoretical models for the evolution of quantitative traits, however, assume that genetic variance is constant through time and identical among different sub-groups of individuals in the population. Yet many populations are structured, with groups of individuals differing in sex, age, size, or developmental stage, which may differ in the amount of genetic variance they harbour for different traits. For instance, previous theory has shown that genetic variance for a trait subject to multiple selection episodes through the course of life decreases with age. Conversely, genetic variance for a trait expressed for the first time late in life is predicted to be higher than that for a trait first expressed when individuals are still young. However, we lack theoretical expectations for other types of structured populations, where individuals vary in the time they spend in different stages.
Here, we develop a set of general recursions to predict the change across time and stages of both the mean and the variance of a Gaussian-distributed trait affecting transitions between discrete stages in a structured population. We track the variation in the phenotypic trait value, the component of the trait that is transmitted to the next generation (the breeding value), and their covariation. We illustrate our predictions by parameterizing the model using demographic data on stage transitions for various plant species and exploring different scenarios of selection on the phenotypic trait. In particular, we show how genetic variance accumulates in some stages and is depleted in others, and how this affects the probability of escaping extinction while adapting to a new environment.

Orateur: Julien Offresson (Institut des sciences de l'évolution-Montpellier)

15:30 → 16:00 Pause café

16:00 → 16:45 Etude du modèle infinitesimal par une méthode hilbertienne

Dans cet exposé, je considérerai un modèle pour la dynamique d'une population -- répartie selon un trait phénotypique -- qui se reproduit sexuellement et qui est soumise à la sélection et à la compétition.  La reproduction sexuelle est modélisée via un terme intégral non linéaire, connu sous le nom de « modèle infinitésimal » de Fisher, qui prescrit que le trait phénotypique de la descendance suit une loi gaussienne autour de la moyenne des traits des géniteurs. Dans le  régime où la variance de la reproduction est petite devant la variance de la sélection, je m'intéresserai à une description explicite de la dynamique obtenue en projetant la solution sur une base de polynômes bien choisie. Cette description permet en particulier d'étudier l'existence de distributions stationnaires et leurs stabilités.
La présentation est basée sur un travail en collaboration avec Sepideh Mirrahimi.

Orateur: Matthieu Hillairet (Institut Montpelliérain Alexander Grothendieck)

16:45 → 17:30 On the approximation of the use of Hermite functions for quantum and statistical physics

We propose a new approach to discretize the von Neumann equation, which is efficient in the semi-classical limit. This method is first based on the so called Weyl's variables to address the stiffness associated with the equation. Then, by applying a truncated Hermite expansion of the density operator, we successfully handle this stiffness. Additionally, we develop a finite volume approximation for practical implementation and conduct numerical simulations to illustrate the efficiency of our approach. This asymptotic preserving numerical approximation, combined with the use of Hermite polynomials, provides an efficient tool for solving the von Neumann equation in all regimes, near classical or not.

Orateur: Francis Filbet (Institut de mathématiques de Toulouse)

ven. 9 janvier

09:15 → 10:00 Evolutionary ecology of structured populations

In natural populations, individuals may have different vital rates depending on their age, size, location, infection status, or immunity. This demographic heterogeneity has important ecological and evolutionary consequences. In evolutionary epidemiology, two important sources of heterogeneity are imperfect vaccination and infection age structure. As a result of this heterogeneity, hosts do not have the same quality for the pathogen depending on their immune or age class. In this talk I will discuss theoretical results that show how this variation in host quality can affect the evolution of pathogen life history traits (e.g. transmission, virulence...).

Orateur: Sébastien Lion (Centre d'écologie fonctionnelle et évolutive-Montpellier)

10:00 → 10:30 Pause café

10:30 → 11:15 Recovering an initial distribution of telomere lengths from measurements of senescence times

Telomeres are repetitive sequences situated at both ends of the chromosomes of eukaryotic cells. At each cell division, they are eroded until they reach a critical length that triggers a state in which the cell stops to divide: the senescent state. In this work, we are interested in the link between the initial distribution of telomere lengths and the distribution of senescence times. We propose a method to retrieve the initial distribution of telomere lengths, using only measurements of senescence times. Our approach relies on approximating our models with transport equations, which provide natural estimators for the initial telomere lengths distribution. We investigate this method from a theoretical point of view by providing bounds on the errors of our estimators, pointwise and in all Lebesgue spaces. We also
illustrate it with estimations on simulations, and discuss its limitations related to the curse of dimensionality.

Orateur: Jules Olayé (Institut de mathématiques de Toulouse)

11:15 → 12:00 Exposé

Orateur: Manon Costa (Institut de mathématiques de Toulouse)