Léo Girardin

Photo de L. Girardin Contact details
Postal address:
Léo Girardin
Institut Camille Jordan
Université Claude Bernard Lyon-1
43 boulevard du 11 novembre 1918
69622 Villeurbanne Cedex
France
Office: 119
E-mail address: myfirstname.mylastname@math.cnrs.fr
Phone:
© Chancellerie de Paris/Julien Benhamou

Curriculum vitae

I am a junior CNRS researcher affiliated with the team MMCS (Mathematical Modelling and Scientific Computing) at Institut Camille Jordan (UMR 5208) at Université Claude Bernard Lyon-1.

Full CV (PDF format): English version/French version.

Research interests

My mathematical interests are reaction–diffusion partial differential equations and systems and mathematical models for population biology (ecology, evolution, epidemiology, population genetics). In particular, I am interested in long-time qualitative behaviors: persistence, extinction and especially propagation phenomena (asymptotic spreading, traveling wave solutions and generalizations of these notions).

Secondary focuses worth mentioning are principal eigenvalues of parabolic and elliptic operators, non-local parabolic and elliptic PDEs, free boundary problems, singular limits and mathematical models for social sciences.

On the biological side, I have studied models of competitive displacement, territorial expansion, evolution of dispersal and spatial sorting in expanding ranges, evolution of Allee effect, populations structured both in space and age, CRISPR-Cas9 gene drive, agro-epidemiological modeling.

Research articles (with arXiv/biorXiv links)

Preprints

  1. with L. Klay, V. Calvez, F. Débarre: Stochastic dynamics at the back of a gene drive propagation wave. 2025.
  2. with T. Giletti and H. Matano: Spreading properties of the Fisher--KPP equation when the intrinsic growth rate is maximal in a moving patch of bounded size. 2024.
  3. with G. Nadin: Planar pulsating traveling wave solutions of non-cooperative Fisher--KPP systems in space-time periodic media. 2025.

Publications

On two-species competition--diffusion Lotka-Volterra systems

  1. with G. Nadin: Travelling waves for diffusive and strongly competitive systems: relative motility and invasion speed. European Journal of Applied Mathematics, 2015, 26(04), 521-534.
  2. Competition in periodic media: I -- Existence of pulsating fronts. Discrete and Continuous Dynamical Systems - Series B, 2017, 22(04), 1341-1360.
  3. with G. Nadin: Competition in periodic media: II -- Segregative limit of pulsating fronts and "Unity is not Strength"-type result. Journal of Differential Equations, 2018, 265(01), 98-156.
  4. with A. Lam: Invasion of open space by two competitors: spreading properties of monostable two-species competition--diffusion systems. Proceedings of the London Mathematical Society, 2019, 119(05), 1279-1335.
  5. The effect of random dispersal on competitive exclusion -- A review. Mathematical Biosciences, 2019, 318, 108271.
  6. with A. Zilio: Competition in periodic media: III -- Existence & stability of segregated periodic coexistence states. Journal of Dynamics and Differential Equations, 2020, 32, 257-279.
  7. with D. Hilhorst: Spatial segregation limit of traveling wave solutions for a fully nonlinear strongly coupled competitive system. Electronic Research Archive, 2022, 30(05), 1748-1773.

On non-cooperative Fisher--KPP systems

  1. Non-cooperative Fisher--KPP systems: traveling waves and long-time behavior. Nonlinearity, 2018, 31, 108-164.
  2. Addendum to 'Non-cooperative Fisher–KPP systems: traveling waves and long-time behavior'. Nonlinearity, 2018, 32, 168-171. (Contains the proof of extinction in the critical case.)
  3. Non-cooperative Fisher--KPP systems: asymptotic behavior of traveling waves. Mathematical Models and Methods in Applied Sciences, 2018, 28(06), 1067-1104 .
  4. Two components is too simple: an example of oscillatory Fisher--KPP system with three components. Proceedings of the Royal Society of Edinburgh - A, 2019, 150(6), 3097-3120.
  5. with Q. Griette: A Liouville-type result for non-cooperative Fisher--KPP systems and nonlocal equations in cylinders. Acta Applicandae Mathematicae, 2020, 170, 123-139.
  6. A note on “Existence and uniqueness of coexistence states for an elliptic system coupled in the linear part”, by Hei Li-jun, Nonlinear Anal. Real World Appl. 5, 2004. Nonlinear Analysis: Real World Applications, 2022, 63, 103385.
  7. Persistence, extinction and spreading properties of non-cooperative Fisher--KPP systems in space-time periodic media. SIAM Journal on Mathematical Analysis, 2025, 57(1), 233-261.

On gene drive reaction--diffusion models

  1. with V. Calvez and F. Débarre: Catch me if you can: a spatial model for a brake-driven gene drive reversal. Bulletin of Mathematical Biology, 2019, 81(12), 5054-5088.
  2. with F. Débarre: Demographic feedbacks can hamper the spatial spread of a gene drive. Journal of Mathematical Biology, 2021, 83, 67.
  3. with L. Klay, V. Calvez, F. Débarre: Pulled, pushed or failed: the demographic impact of a gene drive can change the nature of its spatial spread. Journal of Mathematical Biology, 2023, 87(2), 30, 54.
    This article was awarded the Karl-Peter Hadeler Prize 2023.
  4. with L. Klay, V. Calvez, F. Débarre: The spatial spread and the persistence of gene drives are affected by demographic feedbacks, density dependence and Allee effects. 2025. Accepted for publication in Molecular Ecology.

On nonlocal equations

  1. with M. Alfaro, F. Hamel and L. Roques: When the Allee threshold is an evolutionary trait: persistence vs. extinction. Journal de Mathématiques Pures et Appliquées, 2021, 55, 155-191.

On agro-ecological models

  1. with B. Maucourt: Agro-ecological control of a pest-host system: preventing spreading. SIAM Journal on Applied Mathematics, 2023, 83(3), 1172-1195.

On principal eigenvalues

  1. with I. Mazari: Generalized principal eigenvalues of space-time periodic, weakly coupled, cooperative, parabolic systems. 2024. Accepted for publication in Mémoires de la Société Mathématique de France.

PhD thesis

My PhD thesis was entitled Propagation phenomena and reaction–diffusion systems for population dynamics in homogeneous or periodic media and supervised by Grégoire Nadin and Vincent Calvez. You can find the manuscript here.

Teachings

2022–2025

With Hélène Leman, we are responsible for the “Modélisation mathématique pour l'écologie spatiale” course in the “Maths en action” M2 at Université Claude Bernard Lyon-1.

Miscellaneous might-be-interesting stuff

An interview of me (in French) by the CNRS.

My ORCID profile (0000-0001-8201-2053).

I have a master degree in epistemology and science studies.

A fancier website will replace this austere page. Someday. Maybe. (At least, web accessibility is not an issue here.)

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