Rencontre de la chaire
8 avril 2026 matin
Amphi Rouelle (bâtiment de la baleine - plan
d'accès)
(Museum National d'Histoire Naturelle, Paris).
Programme:
9h45 - 10h00 : Accueil café
10h00 - 10h40 : Pablo Marquet (Pontificia Universidad
Católica de Chile) - "The emergence, maintenance, and dynamics
of biodiversity".
In this talk, two first principles associated to
biodiversity dynamics are examined. The first is niche
construction, which is predicated on the facts that organism
and environments are interlinked and affect their state and
evolution. The second is neutrality, which provides a
stochastic persistence criteria for biodiversity maintenance
and insights on biodiversity dynamics.
10h45 - 11h25 : Lola De Cubber (Université du Littoral
Côte d'Opale) -"Mechanistic Modeling of Marine Ecosystems Using
the Dynamic Energy Budget Framework".
Dynamic Energy Budget (DEB) models describe how an
organism acquires, stores, and uses energy from food to
grow, maintain itself, develop, and reproduce throughout its
life cycle under varying environmental conditions. Based on
their standard structure, they allow the identification of
bioenergetic strategies that can be seen as regularities
across certain types of organisms, enabling generalization
at higher levels of organization. This presentation
illustrates how to use these models to address ecological
questions spanning physiology, population dynamics,
ecosystem structure and functioning, and ecosystem services.
It also highlights the upcoming challenges for the wider
application of these models in the context of climate
change, particularly the difficulty of robust model
calibration, accounting for multiple interacting stressors,
scaling predictions across levels of biological
organization, and integrating adaptive responses such as
phenotypic plasticity and evolution.
11h25 - 11h55 : pause
11h55 - 12h35 : Florence Débarre
(iEES) - "Environmental granularity and the
spatial spread of an allele under
frequency-dependent selection"
When does an allele under positive
frequency-dependent selection spread? The
answer depends on the threshold frequency
over which the selection coefficient becomes
positive, on the inoculum, but also on the
granularity of the environment: An allele
spreading in a spatially continuous
environment may be stopped when the
environment becomes coarser. (While
formulated here in terms of allele
frequencies, the phenomenon also occurs for
population growth with an Allee effect.) An
attempt was made to find the critical step
size of the environment above which a wave
of advance stops. Previous attempts found in
the literature involved approximations
(stated or not), and were therefore not
exact; attempts to refine these results are
presented here. Properly estimating the
critical step size is particularly important
for applications aiming to use coarse
environment structures to limit the spatial
spread of an allele, notably in the context
of gene drive.
