"For the first time the possibility to change certain species sex while maintaining their original sex chromosomes is presented as an excellent opportunity to unravel aspects of sex chromosome evolution. Theory of sex chromosome evolution states that sexually antagonistic genes, i.e. genes that are beneficial to one sex but at the same time harmful to the opposite sex, should often be linked to one of the sex chromosomes. Current knowledge of which genes are responsible for such sexual antagonisms is however limited. The mosquitofish Gambusia affinis can easily be sex reversed and will represent the first ZW sex chromosome system besides birds where questions of sex-biased gene expression, dosage compensation and sex-biased expression through development will be addressed. Candidate sexual antagonistic genes will then be used to gain insight into expression differences in sex reversed individuals, such as male/female or sex-linked/autosomal dissimilarities in responsiveness to the new sex. Mainly, these objectives will be studied applying the new cutting-edge next-generation sequencing techniques (e.g. Roche 454, Illumina’s Solexa, etc.). This project has great potential to contribute both to the fellows and to the European excellence. Through careful planning of training in research and auxiliary topics it is aimed at providing the fellow with complementary skills needed to commence a career as an independent leading scientist."