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SEXSEA, the origin and the evolution of the sexes and reproductive systems: novel insights from a distant eukaryotic lineage - Susana Coelho

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Marie Pinhas-Diena, in charge of scientific communications l tel: +33 (0)1 44 27 22 89 l email: marie.pinhas@upmc.fr

SEXSEA: the origin and the evolution of the sexes and reproductive systems - Susana Coelho

novel insights from a distant eukaryotic lineage

Sexual reproduction is widespread in most eukaryotes. Although the basic mechanisms of sexual reproduction (meiosis and syngamy) are highly conserved, the mechanisms that determine whether a body is male or female are remarkably labile. In genetically controlled sexual systems, sex is determined by the sex chromosomes that have emerged independently and repeatedly during evolution. Sex chromosomes have been studied in only a handful of model organisms, and knowledge about the origin and evolution of the sexes are still surprisingly incomplete.


The purpose of SEXSEA is to exploit the remarkable richness of the sexual characteristics of brown algae to gain new knowledge about functional and evolutionary interactions between sex chromosomes and different modes of reproduction and life cycles present in eukaryotes.

Portrait of Susana Coelho, Research Director.

First, we will use the Ectocarpus brown alga model to reveal the fundamental genetic mechanisms by which sex chromosomes control reproduction and life cycle, including the determination of sex and asexual reproduction by parthenogenesis, but also control size of gametes and the alternation between haploid-diploid phase during the life cycle.


Photo of Ectocarpus. © Delphine Scornet (CNRS)


Second, we will use a combination of experimental and computational approaches to species of brown algae with a selected range of modes of reproduction and life cycles to understand the long-term consequences of evolving variations of these traits on the structure of their sex chromosomes in a phylogenetic context. This analysis will reveal not only fundamental evolutionary forces that act on the sex chromosomes but will also uncover the primordial evolutionary mechanisms that control the main reproduction modes and life cycle in eukaryotes, giving new insight into the origin and changing of sexes.


Laboratoire de biologie intégrative des modèles marins (CNRS/UPMC)Nouvelle fenêtre (in French)


Algal Genetics GroupNouvelle fenêtre (in English)


The website of Susana Coelho's teamNouvelle fenêtre (in English)