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Sex chromosomes have evolved independently in a vast number of species and share common features, including recombination suppression, degeneration, and dosage compensation. These features are however not universal and many species have sex chromosomes lack them, or exhibit them only partially. In particular dosage compensation occurs by different mechanisms and can be local (at the gene-by-gene level) or regional/global (at the chromosomal or portion of chromosomes level)(1-7). New models developed by our team (10-12) suggest an important role of regulatory changes and dosage compensation during early evolution of sex chromosomes. However, the evolution of the different forms of dosage compensation and the transition from local to global compensation has been little studied and remains an enigma. We lack a robust theory to understand how global dosage compensation can evolve. The project of this postdoc is to develop such theory using existing models as building blocks and further develop them.

References:

1. C. H. Chandler, When and why does sex chromosome dosage compensation evolve? Annals of the New York Academy of Sciences 1389, 37-51 (2017).
2. B. Charlesworth, The evolution of chromosomal sex determination and dosage compensation. Current Biology 6, 149-162 (1996).
3. B. Charlesworth, D. Charlesworth, HJ Muller and the Relationship Between Sex Chromosome Degeneration and the Evolution of Dosage Compensation. Genome Biol Evol 17, evaf195 (2025).
4. C. M. Disteche, Dosage compensation of the sex chromosomes. Annual review of genetics 46, 537-560 (2012).
5. A. Muyle, R. Shearn, G. A. Marais, The evolution of sex chromosomes and dosage compensation in plants. Genome Biology and Evolution 9, 627-645 (2017).
6. I. Marin, M. L. Siegal, B. S. Baker, The evolution of dosage-compensation mechanisms. BioEssays 22, 1106-1114 (2000).
7. J. E. Mank, Sex chromosome dosage compensation: Definitely not for everyone. Trends in Genetics 29, 677-683 (2013).
8. T.-L. Ashman, D. Bachtrog, H. Blackmon, E. E. Goldberg, M. W. Hahn, M. Kirkpatrick, J. Kitano, J. E. Mank, I. Mayrose, R. Ming, S. P. Otto, C. L. Peichel, M. W. Pennell, N. Perrin, L. Ross, N. Valenzuela, J. C. Vamosi, Tree of Sex: A database of sexual systems. Scientific Data 1, 140015 (2014).
9. L. W. Beukeboom, N. Perrin, The Evolution of Sex Determination (Oxford University Press, 2014; http://www.oxfordscholarship.com/view/10.1093/acprof:oso/9780199657148…).
10. T. Lenormand, F. Fyon, E. Sun, D. Roze, Sex chromosome degeneration by regulatory evolution. Current Biology 30, 3001-3006.e5 (2020).
11. T. Lenormand, D. Roze, Y recombination arrest and degeneration in the absence of sexual dimorphism. Science 375, 663-666 (2022).
12. T. Lenormand, D. Roze, Can mechanistic constraints on recombination reestablishment explain the long-term maintenance of degenerate sex chromosomes? Peer Community Journal 4, e17 (2024).

The work will be based on chromosomal-scale C++ simulations and analytical work if possible. The postdoc will also be involved in several PhD research projects about regulatory evolution, that include similar methods, and that also include genomic data analysis. Hence, ideally, the applicant will have some background in both theoretical population genetics and genomic data analyses. ues.

The applicant will receive comprehensive training in state-of-the-art theoretical population genetics. He/she will spend most of their time in the Genetic and Evolutionary Ecology group (GEE) at the Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), a large, ecology and evolution-focused research institute in Montpellier, Southern France, with possible visits of project partners elsewhere in France. Montpellier is a lively student town with a beautiful historic center, located about 10 km from the Mediterranean Sea. This postdoc is part of an advanced ERC project ('RegEvol', Thomas Lenormand), addressing novel ideas and theoretical predictions on the role of regulatory evolution for several important fundamental topics in evolutionary biology (sex chromosomes, maintenance of sex, complexity of gene networks, etc.). The postdoc will join the team working on this project, including Christoph Haag, Denis Roze, Sylvain Glémin, and Thomas Lenormand, as well as other people recruited on the project.

PhD or equivalent

Research Field Environmental science, (1) Enthusiasm and genuine curiosity for evolutionary genetics, genomics, and evolutionary biology. (2) A PhD in the subject area of evolutionary biology. Experience with population genetics, evolutionary theory, genomics is desirable. (3) Strong quantitative skills. Experience with programming or bioinformatics is desirable. (4) Strong oral and written communication skills in English (the work language for science at the CEFE is English). (5) Ability to work both independently and in a highly collaborative environment. (6) Well organized and highly motivated.