CAN: Intensive agriculture turned a wild plant into a pervasive weed, study finds

New research published in Science shows how the rise of modern agriculture turned a North American native plant, the common waterhemp, into a problematic agricultural weed.

An international team led by researchers at the University of British Columbia with colleagues at the University of Toronto compared 187 waterhemp samples from modern farms and neighboring wetlands with more than 100 historical samples dating as far back as 1820 that had been stored in museums across North America.

Much like the sequencing of ancient human and neanderthal remains has resolved key mysteries about human history, studying the plant’s genetic makeup over the last two centuries allowed the researchers to watch evolution in action across changing environments.

“The genetic variants that help the plant do well in modern agricultural settings have risen to high frequencies remarkably quickly since agricultural intensification in the 1960s,” said study lead author Julia Kreiner. A postdoctoral researcher in UBC’s department of botany, Kreiner completed her PhD at U of T with study co-authors John Stinchcombe and Stephen Wright, both professors in the department of ecology and evolutionary biology in the Faculty of Arts & Science at U of T.

The researchers discovered hundreds of genes across the weed’s genome that aid its success on farms, with mutations in genes related to drought tolerance, rapid growth, and resistance to herbicides appearing frequently. “The types of changes we’re imposing in agricultural environments are so strong that they have consequences in neighboring habitats that we’d usually think were natural,” said Kreiner.

Read the complete article at www.utoronto.ca.


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