Sexual isolation

A lack of sexual attraction between individuals from distinct groups can be very effective in limiting reproduction between these groups. This barrier effect is thought to have been a key driver of speciation, but how do such sexual isolation processes evolve? What mechanisms lead to a disparity between populations in the way individuals choose their sexual partners?

To address these questions, we study the Jaera albifrons complex, a group of small marine isopods living on the shores of the North Atlantic Ocean.

In these species, females select males based on a tactile courtship involving specialised setae and spines carried by the males› peraeopods. Male sexual traits and female preferences differ between species, resulting in strong sexual isolation. We combine field sampling, lab experiments and population genomics to investigate the processes involved in reproductive isolation. Early findings point to a role for sex chromosomes (ZW system) and chromosomal rearrangements (fusions, fissions, and a reciprocal translocation). We aim to understand how such genetic factors drive the evolution of behavioral sexual isolation.

Participants

• Basile Pajot (PhD 2024-2027), Alan Le Moan (Post-doc 2025)
• Claire Daguin-Thiébaut, Stéphanie Ruault, Jérôme Coudret, Stéphane Loisel, Marion Ballenghien, Didier Jollivet, Charlotte Berthelier, Céline Houbin
• Christelle Fraïsse (Institute of Evolutionary Science of Montpellier), Erwan Corre and Lorraine Guéguen (Analysis and Bioinformatics for Marine Science)
• Rui Faria (Cibio Portugal)

Related publications

• Ribardière A, Daguin-Thiébaut C, Coudret J, Le Corguillé G, Avia K, Houbin C, Loisel S, Gagnaire P-A, and Broquet T (preprint). Sex chromosomes and chromosomal rearrangements are key to behavioural sexual isolation in Jaera albifrons marine isopods. BioRxiv (recommended by PCI Evol Biol).
• Broquet T, Destombe C, Valéro M, Jollivet D (2023). A brief history of speciation research at the Station Biologique de Roscoff (1872-2022). Cahiers de biologie marine 64:9-19 (special issue 150 years anniversary of the station).
• Ribardière A, Pabion E, Coudret J, Daguin-Thiébaut C, Houbin C, Loisel S, Henry S, and Broquet T (2021). Sexual isolation with and without ecological isolation in marine isopods J. albifrons and J. praehirsuta. Journal of Evolutionary Biology 34: 33-48.
• Ribardière A, Centanni J, Dano A, Courdret J, Daguin-Thiébaut C, Houbin C, Kerdoncuff E, Jambut S, Cordaux R, and Broquet T (2018). Female-biased sex ratios unrelated to Wolbachia infection in European species of the Jaera albifrons complex (marine isopods). Journal of Experimental Marine Biology and Ecology 509: 91-98.
• Ribardière A, Daguin-Thiébaut C, Houbin C, Coudret J, Broudin C, Timsit O, and Broquet T (2017). Geographically distinct patterns of reproductive isolation and hybridisation in two sympatric species of the Jaera albifrons complex (marine isopods). Ecology & Evolution 7: 5352-5365.

Main funding

• ANR JCJC Isobar (2013-2018)
• ANR PRC Sexisol (2024-2028)