The City as an Evolutionary Hothouse—The Search for Rapid Evolution in Urban Settings

Abstract

Cities are ubiquitous and, though a novel phenomenon by evolutionary standards, provide a home for many species and exert particularly strong and novel selection pressures on them. They thus offer a unique opportunity to study rapid evolutionary processes. We conducted a scoping review of published studies documenting evolutionary processes in urban environments, focusing primarily on more recent work. Unfortunately, cities have not been attractive environments for biological research and thus remain poorly studied, despite slowly growing interest in recent years. Nonetheless, we found studies documenting the effects of mutation, genetic drift, and selection in cities. However, studies show some geographic bias and were not always as conclusive as might be desired. There is even support for incipient urban speciation. Evidence across the board is less abundant and less conclusive than desirable, suggesting the need for more data collection. The urban setting, with its stronger selection, more common intermixing, and abundance of both human and widespread potential non-human zoonosis hosts and human-associated species offers great opportunities to further document evolution in action and explore its conservation implications.