Evolution, mechanisms of feminization and genetic conflicts in a sex-determining virus – ViF

In many gonochoristic species, selfish alleles or endosymbionts transmitted maternally bias the sex ratio toward the sex that transmits these elements at a higher rate. This Sex-ratio distortion (SRD) then opens the way to ‘genetic conflicts’ in which an SRD suppressor arises because it is more frequently inherited by individuals of the rarer sex, who benefit from higher average fecundity. Although several SRD suppressors caused by endosymbionts are suspected or proven, none has yet been characterized at the molecular level. Furthermore, to understand the genetic conflict associated with the presence of SRD, it is necessary to decipher how an endosymbiont manipulates the reproduction of its host.

To date, two of the three parasitic manipulations that induce SRD - male-killing and induction of parthenogenesis - have been characterized with respect to the genes and molecular mechanisms at play. The mechanisms underlying the last type of manipulation, feminization, remain elusive.

The ViF (Virus-induced Feminization) project aims at filling these gaps by (i) elucidating the molecular mechanism of feminization and (ii) characterizing a suppressor of the SRD induced by feminization, which restores balanced sex ratios in natural populations. To do this, we will apply various methodological approaches, namely genetic engineering, microscopy, phenotyping, transcriptomics, phylogeography population genomics and modelisation, on an exceptional biological model: the first virus known to determine the sex of a host organism.