Cities a Major Factor in Species Evolution.

• Position: URBAN BIOLOGY

Cities are not just hotbeds of human activity. They also are changing the way plants and animals around the world evolve.

"Traditionally, we've thought about evolution as a long-term process that happens in relation to natural environmental features and the interactions among species, but now there is one phenomenon that is rapidly changing many other species, which is how they interact with humans and our built environment," says Jason Munshi-South, professor of biological sciences at Fordham University Bronx, N.Y.

"Humans and our cities are one of the most-dominant forces of contemporary evolution now."

In "Evolution of Life in Urban Environments," a paper by Munshi-South and Marc T.J. Johnson, associate professor of biology at the University of Toronto (Canada), published in the journal Science, the researchers cite direct evidence--after examining the findings of 192 studies--of evolutionary change among more than 100 species living in cities around the world.

While it has been observed since ancient times that certain animals--rats, pigeons, bedbugs, roaches, and mosquitoes, for example--adapt to the presence of humans, a number of recent studies confirm this phenomenon is widespread among species.

Research reveals that a significant number of species have become isolated in cities, in either pockets of habitat that have survived or in other spaces they have adapted to. Urban species have diverged from other populations through multiple evolutionary processes such as genetic drift and natural selection. They also have become different not only from populations in the more-rural surrounding...