Cities around the globe are fueling evolution among microbes, plants, and animals, driving physical mutations and altering gene flow, according to a new analysis in the journal Science. The projected spread of urbanization in coming decades will continue to reshape and create new species in unexpected ways, the study found.

“Urbanization represents the best and largest-scale unintended evolution experiment,” write Marc Johnson of the University of Toronto, Mississauga, and Jason Munshi-South of Fordham University, the authors of the new analysis.

In Tucson, Arizona, for example, house finches have developed longer and wider beaks than their rural counterparts to more easily consume sunflower seeds in bird feeders. In Puerto Rican cities, lizards’ toes have evolved to grip and move more easily on artificial surfaces, like concrete or brick. Several studies have also shown that urban pollution can increase mutation rates of DNA in birds and mammals. A new species of mosquito appears to be emerging that survives underground in sewers and subways.

The new analysis, which examined patterns in 192 studies on urban evolution, said that many threatened or endangered species have also found niches within urban environments that have allowed them to thrive, such as Peregrine Falcons nesting on top of skyscrapers or cliff plants that have adapted to grow on urban substrates.

“We are dramatically changing the way life operates and as a result. having a rapid and dramatic effect on the biodiversity on this planet,” Johnson told the Canadian Broadcasting Corporation. “Understanding how cities, which are the main drivers of climate change and changes in our landscape, are the driver of these biodiversity changes, understanding how it influences the evolution, is critically important to conservation of biodiversity on Earth.”

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