Wild populations must continually adapt to environmental change or risk extinction. For more than fifty years, scientists have described cases of “rapid evolution” in specific populations when their traits (phenotypes) change in response to various stressors. For example, Spanish clover has developed a tolerance to copper from the mine tailings in which it grows, and the horn size of Alberta bighorn sheep has decreased due to trophy hunting. But so far it has not been possible to draw overall conclusions about how different factors (such as harvesting, climate change, invasive species or pollution) are shaping this rapid evolution (now called “contemporary “).
Building on previous work, a team led by McGill University has created a massive new dataset of nearly 7,000 examples of shifting traits in diverse populations around the world, from house sparrows and gray wolves to land snails. water and Canada’s goldenrod. The dataset is 80% larger than anything in the past and documents trait changes that are a mix of evolution and immediate (plastic) responses to the environment.
Human disturbances affect evolution
“We’ve come a long way from the old view of evolution as a slow process to the point where we now realize that everything is evolving all around us all the time,” says Andrew Hendry, professor of biology at the Redpath Museum. of McGill and co-lead author of the recently published article in Molecular ecology.
Researchers have been particularly interested in how various types of human disturbances influence trait changes. “We found a small but real difference in rates of change between human-disturbed and natural populations,” says Kiyoko Gotanda, co-lead author and assistant professor of biological sciences at Brock University, where the data is hosted. “Furthermore, the highest rates of change are almost always those associated with intensive human disturbance,” Hendry adds.
Pollution has a significant impact on evolution
Analyzes of the expanded dataset also confirm that harvesting by humans results in higher rates of change than non-human disturbance, and that introduced populations have increased rates of change. Interestingly, the researchers found that pollution was responsible for the fastest rate of phenotypic change – zinc tolerance in bushy hairy grass increasing by 80% over 26 years, for example. They also suggest that it is now difficult to judge what a “natural habitat” is since climate change is likely to affect most populations.
“The next critical question is how important is this contemporary change to populations, communities, and ecosystems, and nature’s contribution to people,” adds first author Sarah Sanderson, PhD candidate in biology at McGill. “We know, for example, that salmon have become smaller over the last century. This reduction in body size of such a large fish has huge impacts: birds, bears and fish now have less to eat, Indigenous peoples have to catch more fish per meal, and the gain is less for commercial fishermen.”
“Similar effects must surely accompany many other trait changes seen in countless organisms around the world,” Hendry adds.
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