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Norwich scientists’ discovery of ‘genetic gymnastics’ in snapdragons brings new insight into evolution

Bees and pollinators favour flowers that

Bees and pollinators favour flowers that "signpost" clearly, say scientists from the John Innes Centre. Picture: Annabel Whibley

Annabel Whibley

Scientists from the John Innes Centre and the UEA have made a breakthrough discovery about flower colouring genes which they believe could change the way we think about evolution.

Snapdragons in the Snapdragons in the "hybrid zone" in the Pyrenees. Picture: Enrico Coen.

The Norwich-based team has been studying how snapdragons evolved contrasting coloured highlights which act as a “signpost” to attract pollinating bees to the flower’s entry point.

Research leader Prof Enrico Coen from the John Innes Centre said the “genetic gymnastics” which makes this possible – a process known as a hairpin – has been identified in nature for the first time.

“We have been studying these populations for 17 years and we were amazed by this,” he said. “This is a new kind of evolutionary mechanism that had been guessed at, but nobody had actually shown that it was happening in the wild.

“What we found was that the DNA had done a remarkable piece of genetic gymnastics. It created an inverted copy of itself, and it led to these yellow highlights being focused on one spot to say to bees: ‘This is where you need to come to open up the flower’.

“People have done this sort of thing through genetic modification, but this is the first time we had found in nature that evolution had done this.”

The discovery came from a mountain valley in the Pyrenees where two populations of snapdragon species converge: one coloured magenta with yellow highlights, and one yellow with magenta highlights.

Between them is a hybrid zone where flowers displayed intermingled traits from the neighbouring populations, making their signpost less visible and creating much less successful plants, producing fewer seeds and offspring.

The team focussed their study on a gene which creates the pigment for the small yellow highlight on magenta flowers which clearly marks the entry point for bees.

New techniques used by Dr Desmond Bradley at the John Innes Centre revealed the surprise structure in the genome where two copies of the gene had “flipped” to create the hairpin.

Further examination showed that the hairpin was present in the magenta flowers, found in some degree in the hybrid zone, but absent in the yellow populations.

The team believes this mechanism is evidence of a recently-evolved natural phenomenon which maintains the variety of two populations that have independently come up with different solutions for reproductive success – while the hybrid zone acts as a “border control” to maintain the historic differences between the sections either side of the valley.

“We are obsessed with the idea that everything in evolution is optimised to its environment, but we need to get away from the mindset that there has to be a single best solution to every problem,” said Prof Coen. “Often in nature there are multiple solutions, not just one.

“If you look at human behaviour there are certain things we do to adapt to our environment. We have snowmobiles for travelling on snow, boats for water and cars for the road. But other things like whether we drive on the left or the right are not to do with the environment. They have a historical explanation.

“It is not that the environment favours us driving on the left or the right. Historical factors have given us two very good solutions to the same problem – but when we try to combine them, we end up with difficulties.”

The work is the result of a collaboration across the Norwich Research Park, between the John Innes Centre, Prof Tamas Dalmay and his team at the University of East Anglia, and researchers from Austria and China.

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