Our planet has a huge number of different species, and I am striving to understand the way this diversity has formed. Recently, it has been suggested that cross-mating between species (hybridization) under natural settings, may be the first stage in producing some of these new species. This may play an important role in evolution, as unlike most species which evolve over hundreds-of-thousands or millions of years, it would be possible for a new species to form much more rapidly, in less than 100 generations. However, there are many unanswered questions about this area of evolutionary biology, such as: why does hybridization between species happen so often in some organisms and not others? And when does this produce a new species? This research will address these questions in a group of native plants where hybridization between species is common. Eyebrights (Euphrasia) are a group of 19 species found throughout the UK. Unlike many other organisms, hybridization is common, and thought to give rise to a number of new species that are found only in the UK. One such example is the slender-heath eyebright (E. micrantha) and the common eyebright (E. officinalis), which are parents to two new species (E. rivularis and E. vigursii). To understand the way these new species have evolved, I will be collecting eyebrights from across the UK, and using state-of-the-art DNA sequencing techniques to determine the contribution of each of the parent species to the DNA of the new hybrid species. Each of these techniques will allow predictions about the outcomes of hybridization to be tested. For example, it may be predicted that one species will contribute more genes to the new species than the other. This would arise when a species produces larger flowers that are more attractive to pollinators, and so the initial hybrid will go on to mate recurrently with this large flowered species. When this occurs over many generations, most genes will come from one parent, with just a few from the other parent. By sequencing a large number of genes in the new species, as well as both the parents, we can compare the proportion coming from each of the parents. Overall, these results will greatly help our understanding of the way new species evolve, particularly rare species that are of recent origin (in the last 10,000 years). This is of great importance to conservationists in the UK, who are trying to protect rare and endangered species. By understanding the way new eyebright species have evolved, conservation biologists can make new plans that help protect the processes involved in generating new species. This will ensure the survival of not only rare species that are currently present, but those which may evolve in the near future. Such action plans would include conserving pairs of species that hybridize and are known to produce hybrid species, as well as maintaining areas of habitat that favour hybridization.