Scottish flower shows origin of species is a repeatable phenomenon

A new species can start at one place and also another and evolve separately, says a scientist from the University of Stirling in Scotland who discovered a new Scottish flower and then made an unexpected second finding of the same species 350 miles further north.

Dr. Marfio Vallejo-Marín, a plant evolutionary biologist, first discovered the yellow monkey flower (Mimulus peregrinus) in 2012 on the bank of a stream in South Lanarkshire in southern Scotland.

Two years later during a field trip, Dr. Vallejo-Marín detected the impressive yellow flower 350 miles north near Stromness on the Orkney Islands off the north coast of Scotland.

Mimulus peregrinus

The new species Mimulus peregrinus. (Image: University of Stirling)

Dr. Vallejo-Marín’s, along with colleagues from Queen Mary University of London, Whitman College (USA), and the College of William and Mary (USA), published their researcher in the academic journal Evolution.

Same species evolved multiple times in different locations

Dr. Vallejo-Marín, Senior Lecturer in the School of Natural Sciences at the University of Stirling, said:

“Orkney was a missing region which hadn’t been sampled. 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 recognise the subtle differences.”

 

“Usually a species forms once in a particular location then spreads to other regions. 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.”

The flower’s name – Mimulus peregrinus – given by Dr. Vallejo-Marín, translates as the foreigner, because it originates from two invasive species first brought to Britain from South America and the US in the 1800s.

A particularly rare find

Given that hybrid plants of its kind are usually infertile, this was a particularly rare find.

In this case, the hybrid doubled the amount of DNA within its cells and evolved to form a new species in a process called polyploidisation (multiplication of the whole chromosome complement), the same mechanism by which cotton, wheat and tobacco originated.

Dr Vallejo-Marín said:

“It is impossible to say whether Mimulus peregrinus evolved first in the south or in the north of Scotland, 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. 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.”

Citation: Speciation by genome duplication: Repeated origins and genomic composition of the recently formed allopolyploid species Mimulus peregrinus,” Mario Vallejo-Marín, Richard J. A. Buggs, Arielle M. Cooley and Joshua R. Puzey. Evolution. DOI: 10.1111/evo.12678.

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