The emergence of early relationships between flower color and animal pollinators has been a long-standing mystery. However, a recent study published in Proceedings of the Royal Society has shed light on this phenomenon by examining the visual environments in which the ancestors of modern bees foraged from flowers.
The researchers measured and analyzed the light reflected from present-day flowers, as well as the natural backgrounds such as rocks, soil, sticks, bark, and leaves that surround them. Using this data, they created computer simulations that recreated the visual environment when the first flowers appeared.
The study found that insect color vision predates the evolution of flowers. Bees, which are now important pollinators of flowering plants, including food crops, use ultraviolet, blue, and green sensitive photoreceptors to detect and differentiate rewarding flowers. Humans, on the other hand, perceive color using blue, green, and red sensitive photoreceptors.
The researchers believe that bees’ visual systems may have been influenced by evolution to efficiently operate in the environment they inhabited when the first flowers emerged. By the time flowering plants appeared, bees’ ancestors had already evolved color vision, which has persisted throughout their evolutionary history.
The researchers collected background samples from various locations in Australia, an ancient continent with geological features that would have been present during the time when the first flowers appeared. They measured the reflective properties of these samples using a spectrophotometer and used the data to create a database of materials that would have been part of the visual environment of flying insects over 100 million years ago.
Using computer simulations, the researchers tested the visibility of today’s flowers against the simulated backgrounds. They found that flowers pollinated by bees stood out as stronger signals compared to their natural backgrounds. This suggests that flowering plants evolved vivid colors to facilitate color perception by bees.
The study also revealed that bird-pollinated flowers evolved marker points towards longer wavelengths than bee-pollinated flowers. Birds, which became flower visitors millions of years after insect pollination evolved, have a different color vision system with four types of color photoreceptors. They can see long-wavelength red colors that bees cannot easily process against natural backgrounds.
The researchers emphasize the importance of protecting bees and their habitats, as they are major drivers of floral evolution. With the changing climate, it is crucial to understand how pollination and plant reproduction may be affected. Failure to protect these insects and their habitats could result in the loss of fundamental aspects of life that we all enjoy and rely on.
