The authors examine a coevolutionary arms-race between plants (Brassicales) and butterflies (Pieridae). The production of novel toxins in plants and the ability to metabolize and tolerate the toxins in butterflies coincides with single gene and whole-genome duplication events within each taxa. In each case adaptations occurred through the retention and neofunctionalization of duplicated genes. It’s not salmon but it’s a great reminder of the evolutionary impact that duplicated genes can have.