DNA analysis reveals gene copy number variation drives rapid adaptation in invasive plants

A breakthrough method for analyzing the DNA of centuries-old plant samples has given scientists an edge in combating the spread of invasive plants. Researchers from Monash University and the University of Melbourne found the rapid adaptation of invasive plants is driven by their ability to gain and lose genes, a phenomenon known as “copy number variation.”

The discovery came while studying the invasive, noxious weed ragweed, which originated in North America before being transported to Europe and Australia. The work is published in the Proceedings of the National Academy of Sciences.

Ragweed is highly invasive, significantly impacting agriculture and a major producer of hay fever-inducing pollen.

The research analyzed DNA samples from plant samples collected as early as 1830, revealing strikingly similar patterns of adaptation across both native and invasive populations.

Lead researcher Jonathan Wilson said the findings suggested the same genetic mechanisms are reused to tackle comparable environmental challenges when they invade a new area.

Dr. Wilson undertook the research while completing his Ph.D. at Monash University, and is now a research fellow at the University of Melbourne.

“We developed a new method to detect large gains and losses of DNA, even in old and degraded DNA from museum specimens,” Dr. Wilson said.

“This allowed us to track the evolution of these large genetic changes during the invasion and uncover evidence that natural selection likely contributed to their spread.”

The research also identified the gain or loss of the gene targeted by the herbicide glyphosate, which may provide critical insights into the evolution of herbicide resistance, paving the way for more effective weed management strategies.

“This knowledge could be instrumental in developing better strategies to mitigate the spread of invasive weeds,” Dr. Wilson said.

“This will have a huge impact on our farmers who are constantly dealing with the threat of invasive plants.

“In the case of ragweed in particular, it is already a major contributor to hay fever in Europe, and we hope this research will help control the weed before it becomes a big problem in Australia.”

Senior researcher, Monash University Associate Professor Kathryn Hodgins, said the findings provide rare insights into how ragweed has rapidly evolved, further illustrating the important role of gene gain and loss in facilitating adaptation.

“Gains and losses of genes, or copy number variants, are a key driver of adaptation, yet they are often overlooked in many studies of diverse species due to technical challenges,” Associate Professor Hodgins said.

“Our study demonstrates that we can leverage existing datasets to detect these variants, opening the door to important new insights that have largely gone unexplored.”