Welcome to the CEFE

The CEFE is currently the largest French research center in Ecology and Evolutionary Ecology. Our Mission: perform independent, fundamental scientific research on the dynamics of biodiversity, planetary environmental change, and sustainable development. The links between society and ecology is a theme of increasing importance in oour research.

If you are interested in who does what on a specific theme or topic at CEFE, please go to the WHO DOES WHAT tab and use the proposed tags. You will have direct access to the pages of the persons listed for a given tag.

If you are interested in what the different research Departments at cefe do and the focus of their respective teams, please go to the RESEARCH tab and navigate the Departments and their teams.

Seminars of ecology and evolution of Montpellier

  • Meredith Cenzer

    7 mai 2021, 16h00 (diffusion en visioconférence). Maladaptation in a changing world

  • Sutirth Dey

    16 avril 2021, 11h30 (diffusion en visioconférence). Size matters: Population size and adaptation in bacteria.

Daniel Weinrich

5 mars 2021, 11h30 (diffusion en visioconférence).

When does the direction of natural selection depend on population size ?

Daniel Weinrich

Link to seminar will be posted here

Department of Ecology and Evolutionary Biology, and Center for Computational Molecular Biology, Brown University, Providence, Rhode Island


Classical evolutionary theory holds that the efficiency, but not the direction, of natural selection depends on population size. In small populations, drift overwhelms selection, rendering all fitness-affecting mutations selectively neutral. Yet, beneficial mutations never become deleterious and deleterious mutations never become beneficial. Remarkably, several mutations, including in modifiers of recombination and mutation rate, have now been shown to be favored at some population sizes but disfavored at others, contradicting established theory.  Previously, we have designated this phenomenon sign inversion. Here we show that all mutations susceptible to sign inversion can confer both fitness costs and benefits on their carriers that vary either between mutant lineages or across time within the same lineage. Using computer simulations, we demonstrate that both between-lineage and within-lineage variability can cause sign inversion and elucidate the common mechanism. Our results confirm that variability in the sign of selective effect is ultimately necessary for sign inversion, which occurs because selection against carriers bearing the cost and selection for carriers enjoying the benefit are overwhelmed by drift at different population sizes.

Recent publications:

1.     https://www.pnas.org/content/115/13/3422

2.     https://elifesciences.org/articles/51177

3.     https://www.genetics.org/content/203/2/923.article-info