Rapid Evolution Aids Invasive, Exotic Plant Species in Spread to New Environments

Rapid evolution could be giving invasive species a huge advantage. Scientists have found that this process can help non-native plant species spread in new environments--a discovery that shows the importance of preventing the spread of invasive species.

In this case, the researchers examined the Pyrenean rocket (Sisymbrium austriacum subsp. Chrysanthum). This plant grows in the mountains in southern Europe and is particularly prevalent in the Pyrenees. Yet this species has now spread to Belgium and was first reported there in the first half of the 19^th century. It's likely that seeds from the plant were introduced alongside the wool industry around Verviers. Because of the well-documented history of this plant's spread, the researchers decided to take a closer look at its evolution to see how it was so successful.

"We found dried specimens of the Pyrenean rocket in herbaria from the 19^th and 20^th centuries and were able to isolate DNA from these samples," said Katrien Vandepitte, one of the researchers, in a news 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."

So what did they find? It turns out that the greatest divergence was in a set of genes that regulate flowering time. It turns out that the Belgian variant bloomed later. Not only that, but this variant genetically adapted rapidly-in only about 20 generations. This likely allowed the plant to both survive and thrive.

"Our findings are important because until now evidence supporting the hypothesis that exotic plants can spread after a period of rapid genetic adaptation has been very scant," said Vandepitte in a news release. "These plants can be present in small numbers for years before spreading as a result of genetic adaptation. 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."

The findings are published in the journal Molecular Ecology.