Unique Monkeyflower Species Sheds Light on Plant Evolution

A unique monkeyflower species is shedding light on plant evolution, according to a new study.

Back in 2012, Dr. Mario Vallejo-Marin, from the University of Stirling, first unearthed a new species of monkeyflower on the bank of a stream in South Lanarkshire, Southern Scotland. But now, the scientists has made an unexpected second finding, locating the yellow flower some 350 miles north, near Stromness on the Orkney Islands off the north coast of Scotland.

"Orkney was a missing region which hadn't been sampled," Vallejo-Marin, a plant evolutionary biologist, said in a statement. "There were different varieties of monkey flower on the island, but when we spotted this population I knew it was unusual as after looking at hundreds of plants, you get to recognize the subtle differences.

"Usually a species forms once in a particular location then spreads to other regions," he explained. "In this case, the opposite has occurred as the same species has evolved multiple times in different places. It shows that when the conditions are right, the origin of species is a repeatable phenomenon."

After the initial discovery, the Scottish species was named Mimulus peregrinus (meaning "the foreigner"), given its origins from two invasive species first brought to the UK from the US and South America in the 1800s.

It was a particularly rare find given hybrid plants of its kind are normally infertile. Instead, it doubled the amount of DNA in its cells and evolved to form a new species - a process known as polyploidisation.

"It is impossible to say whether Mimulus peregrinus evolved first in the south or in the north of Scotland," said Vallejo-Marin, "but our discovery of a very young species of this kind has allowed us to study evolution as it happens. We only know of a handful of other plant species as young as Mimulus peregrinus and so in this respect it is like looking at the big bang in the first milliseconds of its occurrence."

"The process of evolution it has followed is particularly interesting and adds complexity to our conception of the tree of life," he added. "Instead of branching out as it grows, Mimulus peregrinus is an example of how some branches can come back together again and spawn new species that are in part the combination of their ancestors."

The results were published in the journal Evolution.

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