[PCI Evolbiol] Jaera albifrons: the re-emergence of a model system for speciation research in the genomic era

Preprint recommended: Ribardière et al. (biorxiv) Sex chromosomes and chromosomal rearrangements are key to behavioural sexual isolation in Jaera albifrons marine isopods https://www.biorxiv.org/content/10.1101/2025.01.08.631900v3

 Recommendation :  Lenormand, T. (2025) Jaera albifrons: the re-emergence of a model system for speciation research in the genomic era. Peer Community in Evolutionary Biology, 100854. https://doi.org/10.24072/pci.evolbiol.100854

Charles Bocquet met Georges Teissier at just the right moment. In 1945, the Second World War was coming to an end, and with it the resistance activities of Teissier and other researchers who frequented the Roscoff Biological Station, including Yvette Neefs. Within a year, Georges Teissier would take over the leadership of the CNRS, but he was already director of the SBR (a role he would keep until his retirement in 1971), and above all, he had already spent 25 years devoted to evolutionary biology and to the biodiversity of the intertidal zone. So when Charles Bocquet, 27 years old, met Teissier in Roscoff, he oriented his research toward the biology and evolution of intertidal invertebrates (copepods and isopods, among them the Jaera albifrons).

Charles Bocquet also met Georges Teissier in just the right place. Since the beginning of the twentieth century, the Roscoff Biological Station had been visited by nearly all the (few) French biologists who supported Darwinism, genetics, and later the synthetic theory of evolution. Starting with Yves Delage and Marie Goldsmith who, as early as 1909, were already discussing an integration of Darwinian theories with Mendel’s findings on heredity in a pioneering chapter (one could say visionary: the synthetic theory would take another thirty years to emerge).

Charles Bocquet, with his mind in the nascent revolution of evolutionary biology and his feet in the exceptionally rich intertidal waters of Roscoff, observed copepods and isopods. He observed them closely. During his nine years as assistant or head of practical work at the SBR (and later at the Luc-sur-Mer station), he made tens of thousands of meticulous measurements on individuals only a few millimeters long. He became the first researcher in Roscoff to devote himself to the theme of the origin of species (that is, the evolution of isolating barriers) and found in the Jaera albifrons complex an excellent study model. He distinguished six species, documented behavioral barriers (males brush the backs of females in the hope of being accepted as sexual partners, but their specialized courtship setae differ between species, and females are not fooled) and ecological barriers (the different species can locally occupy distinct micro-niches). In his thesis, for example, he speculated that sexual isolation may have evolved in allopatry, followed by ecological specialization after secondary contact. He wrote this in 1953.

The Jaera albifrons model enjoyed a golden age in the 1960s and 1970s with the publication of six additional theses on the subject (including the very first French thesis using allozymes, by Marie-Louise Cariou in 1977), then it was abandoned in favor of insect species, easier to rear far from the sea (notably at the Laboratory of Evolutionary Genetics and Biometry in Gif-sur-Yvette, founded by Teissier in 1951).

Then in 2012, at the Gulf Stream café, Franck Gentil (then a lecturer and expert on coastal marine biodiversity) patiently explained to a new CNRS recruit that the various marine models he was considering for developing a new research line on speciation were completely unsuitable (too rare, too difficult to sample, too difficult to rear, too difficult to identify…). And he concluded with: “And otherwise, have you heard of Jaera albifrons? I have the theses of Bocquet and Solignac in my office.”

To learn more about the history of research on speciation at the Roscoff Biological Station, see an article written for the station’s 150th anniversary: Cah. Biol. Mar. (2023) 64: 9–19, DOI: 10.21411/CBM.A.3DAF598C