Human beings mold the environment in which they live to their will and cities are among the most profoundly transformed environments on Earth. Now, new research led by evolutionary biologists at the University of T. Mississauga (UTM) and published in the journal Science shows that these urban environments are altering the way life evolves.
Is this parallel evolution happening in cities around the world?
The Global Urban Evolution Project (GLUE) analyzed data collected by 287 scientists in 160 cities in up to 26 countries, who sampled the white clover plant in their cities and nearby rural areas. It is a plant native to Europe and western Asia, but it is found in cities around the world. They collected more than 110,000 samples along gradients from cities, suburbs, and also outside the countryside.
Scientists say they have found the “clearest evidence yet” that humans in general, and more specifically the cities they build, are a “dominant force” driving the evolution of life around the world. This statement is because the data showed that white clover frequently evolves in direct response to environmental changes that take place in urban settings; that is, the construction of cities changes the way life evolves.
We alter the way plant life evolves
“We’ve known for a long time that we’ve changed cities quite profoundly and drastically altered the environment and ecosystems,” James Santangelo, a biology doctoral student at UTM and co-director of the study, said in a press release. “But we just showed that this happens, often in similar ways, on a global scale.”
The GLUE study illustrates that environmental conditions in cities tend to be more similar to each other than to nearby rural habitats. Thus, the center of New York (USA) is more similar to the center of Tokyo (Japan) than to the farmland and forests that surround New York City and vice versa.
Changes in white clover
White clover ( Trifolium repens ) is a plant that produces hydrogen cyanide as a defense mechanism against herbivores and to increase its tolerance to water stress, and scientists discovered that those clovers that grow in cities produce less hydrogen cyanide than those clovers growing in neighboring rural areas due to adaptation to urban environments. Regardless of the weather.
“There has never been a field study of evolution on this scale, or a global study of how urbanization influences evolution,” said evolutionary biologist Marc Johnson of the University of Toronto Mississauga (UTM).
“For urbanization to drive parallel evolution, urban areas must converge on environmental features that affect an organism ‘s fitness,” the researchers explained in their paper.
“This study is a model for understanding how humans change the evolution of life around us. Cities are where people live , and this is the most compelling evidence we have that we are altering the evolution of life around us.” Beyond ecologists and evolutionary biologists, this is going to be important for society,” says Rob Ness, assistant professor of biology at UTM and co-author of the paper.
That finding holds true for cities in various climates , and the implications go far beyond the humble clover plant.
“This knowledge could help conserve some of the most vulnerable species on Earth , mitigate pest impacts, improve human well-being, and contribute to understanding fundamental eco-evolutionary processes,” the researchers conclude.
Referencia: James S. Santangelo, Global urban environmental change drives adaptation in white clover, Science (2022). DOI: 10.1126/science.abk0989. www.science.org/doi/10.1126/science.abk0989
