"Rapid Evolution" Keeps Invasive Plants Spreading

A mountain-dwelling plant species that invaded Belgium in the 19th century somehow managed to adapt to the region's varied environment in less than 20 generations. Researchers suggest that this "rapid evolution" may be how the world's multitude of invasive plants continue to spread, despite the fact that they are often unaccustomed to new environments.

The Pyrenean rocket is a well-documented harmless plant that resides in the Pyrénées mountain range in southwest Europe. However, in the early 19th century, the plant somehow found its way into central Belgium, even invading urban parts of the country and valley regions - which are vastly different from the plant's original home.

A study published in Molecular Ecology details how Belgium researchers collected historical samples and data from studies of the colonization of the Pyrenean rocket dating as far back as from when the plant was  first introduced to Belgium alongside the wool industry, with trade carts unknowingly carrying rocket seeds great distances from their ancestral home.

"We found dried specimens of the Pyrenean rocket in herbaria from the 19th and 20th centuries and were able to isolate DNA from these samples," author Katrien Vandepitte of the Plant Conservation and Population Biology Research Group explained in a press release.

"We then compared this DNA with the genetic profile of contemporary samples from Belgium and the Pyrenees. This gave us a unique opportunity to reconstruct when and how an exotic plant species genetically adapted to a new environment," she added.

Interestingly, the analysis showed that the Pyrenean rocket had adapted to its new environment extremely rapidly, finding that flowering time - a very important factor to the survivability of a plant - changed to accommodate for Belgium's varied seasons.

The study also suggests that invasive plants could spread in a new region very suddenly, after a small population develops the right genetic adaptations all at once.

"The Pyrenean rocket is a harmless plant, but some exotics can become a real plague. And this can occur even after a period of unproblematic presence in a non-native environment," Vandepitte warns.

The study was published as the cover article for the May issue of Molecular Ecology.