Men and women have almost the identical set of genes, they differ in many traits. The same is true for fruit flies. A team of researchers from Vetmeduni Vienna has now shown that these differences can be important for adaptations to new environmental conditions. Using experimental evolution in the laboratory, Drosophila males and females developed different adaptations upon exposure to a high temperature. These adaptations are being driven by altered sex-biased gene regulation from standing genetic variation, rather than by new mutations. This mechanism can facilitate rapid evolutionary responses – an insight that is also of enormous relevance for humans.