Bees the key to flower colour evolution

Plants separated by vast oceans and 34 million years evolved to produce the same coloured flower petals because of their reliance on bees for pollination, according to new research.

In a study published today in the Proceedings of the Royal Society B, scientists from Monash University, RMIT University and the Swedish Museum of Natural History demonstrated how flowering plants, or angiosperms, in Australia and Europe have made use of the same colours to attract bees.

Lead researcher Dr Adrian Dyer of Monash University's Department of Physiology and RMIT's School of Media and Communications worked with Monash colleagues Dr Bob Wong, Sky Boyd-Gerny and Vera Simonov from the School of Biological Sciences, and Professor Marcello Rosa, also from the Department of Physiology on the study.

Dr Dyer said Australia was a good subject for studying flower evolution because it separated from other continents 34 million years ago.

"Australia's long-term isolation means that species of plants here and in Europe independently evolved to have similarly coloured petals," Dr Dyer said.

"Our research shows that the common factor here is the known colour vision discrimination abilities of bees. The plants have, over time, developed petals that will attract bees to act as pollinators."

The research showed that certain plants have optimised their petal colours to be easily perceived by bees. Over time, bees have the capacity to learn to associate these flowers with food.

"Bees have trichromatic vision based on ultraviolet, blue and green photoreceptors, so what they see is very different from what we see. However, bees from around the world all appear to have very similar colour vision," Dr Dyer said.

"Previous research has determined that colour vision present in modern bees actually evolved before angiosperms, meaning the plants probably adapted their flower colour to take advantage of pre-existing conditions."

Bees tend to be 'flower constant', repeatedly visiting one type of plant if it continues to provide food. Taking advantage of this to maximise bee visits is an efficient way for plants to ensure that pollen is distributed to others in their species, rather than relying on random wind distribution.

"Currently there is little known about plant-pollinator relationships in Australia; this work shows just how important bees have been to influencing flower colour evolution on this enormous island continent," Dr Dyer said. 

Provided by Monash University