Widely used weed killer harming biodiversity
One of the world鈥檚 most widely used glyphosate-based herbicides, Roundup, can trigger loss of biodiversity, making ecosystems more vulnerable to pollution and climate change, say .
The widespread use of Roundup on farms has sparked concerns over potential health and environmental effects globally. Since the 1990s use of the herbicide boomed, as the farming industry adopted 鈥淩oundup Ready鈥� genetically modified crop seeds that are resistant to the herbicide. 鈥淔armers spray their corn and soy fields to eliminate weeds and boost production, but this has led to glyphosate leaching into the surrounding environment. In Quebec, for example, traces of glyphosate have been found in Mont茅r茅gie rivers,鈥� says Andrew Gonzalez, a McGill biology professor and Liber Ero Chair in Conservation Biology.
To test how freshwater ecosystems respond to environmental contamination by glyphosate, researchers used to expose phytoplankton communities (algae) to the herbicide. 鈥淭hese tiny species at the bottom of the food chain play an important role in the balance of a lake鈥檚 ecosystem and are a key source of food for microscopic animals. Our experiments allow us to observe, in real time, how algae can acquire resistance to glyphosate in freshwater ecosystems,鈥� says post-doctoral researcher Vincent Fug猫re.
Ecosystems adapt but at the cost of biodiversity
The researchers found that freshwater ecosystems that experience moderate contamination from the herbicide became more resistant when later exposed to a very high level of it 鈥� working as a form of 鈥渆volutionary vaccination.鈥� According to the researchers, the results are consistent with what scientists call 鈥渆volutionary rescue,鈥� which until recently had only been tested in the laboratory. Previous experiments by the had shown that evolutionary rescue can prevent the extinction of an entire population when exposed to severe environmental contamination by a pesticide thanks to the rapid evolution.
However, the researchers note that the resistance to the herbicide came at a cost of plankton diversity. 鈥淲e observed significant loss of biodiversity in communities contaminated with glyphosate. This could have a profound impact on the proper functioning of ecosystems and lower the chance that they can adapt to new pollutants or stressors. This is particularly concerning as many ecosystems are grappling with the increasing threat of pollution and climate change,鈥� says Gonzalez.
The researchers point out that it is still unclear how rapid evolution contributes to herbicide resistance in these aquatic ecosystems. Scientist already know that some plants have acquired genetic resistance to glyphosate in crop fields that are sprayed heavily with the herbicide. Finding out more will require genetic analyses that are currently under way by the team.
About the study
"" by Fug猫re V., H茅bert M.-P., Costa N.B., Xu C.C.Y., Barrett R.D.H., Beisner B.E., Bell G., Fussmann G.F., Shapiro B.J., Yargeau V., and Gonzalez A. is published in Nature Ecology & Evolution. DOI: .
The authors acknowledge support and operating funds from the Natural Sciences and Engineering Research Council of Canada (NSERC), the Fonds de Recherche du Qu茅bec 鈥� Nature et Technologies (FRQNT), the Canada Research Chair Program (R.D.H.B., A.G., B.J.S.), the Quebec Centre for Biodiversity Science (QCBS), and the Groupe de Recherche Interuniversitaire en Limnologie et environnements aquatiques (GRIL). The Canadian Foundation for Innovation and the Liber Ero Chair in Biodiversity Conservation provided funding to A.G. to construct the LEAP mesocosm facility.
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