In the short-term the costs of sexual reproduction seem to outweigh its benefits, leaving the widespread success of sex as an evolutionary conundrum. The proposed project will empirically test recent high-profile models for the maintenance of sex, which predict higher rates of sex in individuals that are poorly adapted to their environment than in those that are well adapted. This process allows genes for sex to escape from unfavourable genetic backgrounds and hastens local adaptation of populations to their environment. This work aims to test how an organism’s match with its environment influences the fundamental trait of reproductive mode, and contribute to solving a long-standing puzzle of evolutionary biology.