Humans are a dominant force in plant evolution, says Canadian study

By Brooklyn Neustaeter, CTVNews.ca Editor

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Toronto, Ontario (TVC network) — A new study by biologists at the University of Toronto Mississauga (UTM) suggests that urban environments are changing the way plant life evolves.

The study, published Thursday in the peer-reviewed journal Science, reports that humans are constantly reshaping the environment by building cities, which is changing the way life evolves.

According to the study, the Global Urban Evolution Project analyzed data on white clover plants collected by 287 scientists in 160 cities and their surrounding rural areas, in 26 countries, including Toronto, Tokyo, Melbourne and Munich.

Scientists say they have found the ‘clearest evidence yet’ that humans in general, and the cities they build specifically, are a ‘dominant force’ driving the evolution of life through the world. Scientists say this because data has shown that white clover frequently evolves in direct response to environmental changes that occur in urban settings.

“We’ve known for a long time that we’ve changed cities quite profoundly, and we’ve significantly altered the environment and ecosystems,” said James Santangelo, a UTM biology PhD student and co-lead on the study, in a press release. “But we just showed that it happens, often in similar ways, on a global scale.”

According to the study, environmental conditions in cities were found to be more similar to each other than to neighboring rural settlements. For example, the scientists reported that downtown Toronto was found to be more comparable to downtown Tokyo, rather than the surrounding farmlands and forests outside of the city.

In addition to observing the overall adaptation to cities, the scientists say they have been able to identify the genetic basis of this adaptation, as well as the environmental drivers of evolution.

White clover, a low-growing perennial commonly found in lawns, produces hydrogen cyanide both as a defense mechanism against herbivores and to increase its tolerance to water stress. Scientists chose to examine this plant because it is one of the few organisms present in almost every city on Earth.

According to the study, white clover growing in cities generally produces less hydrogen cyanide than those in nearby rural areas due to “repeated adaptation to urban environments.”

Scientists say that changes in the number of herbivores and the presence of water stress in cities cause white clover to adapt differently from plants in rural areas. The study says this finding holds for cities in a variety of climates, which they say could have implications for other plants and even humans.

“This study is a model for understanding how humans are altering the evolution of life around us,” Rob Ness, an assistant professor of biology at UTM, said in the statement. “Cities are where people live and this is the most compelling evidence we have that we are changing the evolution of life in them.”

“Beyond ecologists and evolutionary biologists, this is going to be important for society,” he added.

With the study showing that humans are driving evolution in cities, the scientists say the data can be used to develop strategies to better conserve rare species and help them adapt to urban environments.

The scientists note that the findings may also help prevent unwanted pests and diseases from adapting to human environments.

However, the authors say this study is just the beginning.

Collecting more than 110,000 clover samples from cities and their neighboring rural areas around the world, scientists have sequenced more than 2,500 clover genomes, creating a “massive dataset” that can be studied for years to come. to come.

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