Nick Barton is an evolutionary biologist. Since 2008, he is Professor at IST Austria. His research centres on understanding the evolution of traits which depend on interactions between large numbers of genes. Such interactions determine the way populations adapt in response to natural and artificial selection, and also the way they diverge to form separate species. The research involves both theoretical work on polygenic variation, and field studies of hybrid zones. These are narrow regions where different populations meet and hybridise; they can be used to find the genetic basis of species differences, and to measure rates of selection and gene flow under natural conditions. Hybrid zones are found in many species, so his research involves toads, butterflies and grasshoppers.