Genome evolution following transition to separate sexes

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Males and females of the same species are often quite different from each other (i.e. exhibit sexual dimorphism). In fact, in some species the differences between genders can be stronger than between individuals of different species or even genera. In humans these differences (e.g. in behaviour) are partly cultural, but to a large extent they are determined by genes. This is more surprising than it may seem as the two sexes share almost identical sets of genes and separate regulatory pathways have to evolve in order to build different male and female phenotypes from a shared pool of genes. How long does it take to develop sexual dimorphism when a species switches from a hermaphroditic state to separate sexes (dioecy)? What happens at the genome level when such transition occurs? These questions will be addressed in this project using a plant species that evolved dioecy and sex chromosomes only a few million years ago.Unlike most plants, Silene latifolia has separate males and females and whether an individual develops as a male or a female depends on the presence or absence of the Y chromosome, not dissimilar to the situation in many animal species (e.g. in humans). However, unlike humans, where sex chromosomes are quite ancient (~200 million years), S. latifolia evolved sex chromosomes relatively recently, within the last ~10 million years, which provides an opportunity to study evolutionary processes at the most interesting early stages of their evolution. This project will use high-throughput DNA sequencing to 'read' the genome of S. latifolia and compare it to the genome of a closely related species Silene vulgaris that does not have separate sexes nor sex chromosomes. Comparing the two genomes it will be possible to study how the genome of S. latifolia evolved following transition to separate sexes in this species.