Climate change is already having a profound impact on cities, as global urbanization pushes more and more people to live in them. The animals who cohabitate with human, whether we appreciate their presence or not, are changing too. Specifically, there's been an increase in invasive species — a term used to describe introduced organisms that bring dramatic and often destructive changes, and sometimes can drive other species to extinction.
But here's the thing: Invasive species don't stop evolving themselves. Consider the infamous brown rats of New York City, which have evolved longer noses and shorter upper molar tooth rows, the better to enjoy the Big Apple's colder weather and higher-quality food. Other invasive species are adapting behaviorally, physically and genetically to life in cities as well. While invasive species pose major public health implications and can certainly affect humans' quality of life, their adaptive abilities can rival those of human migrants and pose a puzzling question: Who's the real invader here?
