A team of researchers from the UK’s John Innes Centre, together with their colleagues from Austria, China, and Australia, has discovered how wild snapdragons produce delicate yellow gradients in their colouring. It turns out that this “makeup”—invisible to the human eye but critically important for pollinators—is controlled by seven genes: three regulate purple colour, and four govern yellow.
The scientists used a hybrid zone in the Pyrenees, where two plant species meet, as a natural laboratory. Natural selection keeps this zone within just one kilometre, because the hybrid orange and white shades, while appealing to gardeners, are less attractive to bees.
The study revealed how genes precisely regulate the yellow gradient: in one variety it is steep, in another it is more gradual. Even the subtle hues that humans can barely distinguish are detectable by bees, making each gene a target of intense natural selection. This was reported in Science Advances.
Co-author Dr Desmond Bradley, who has been studying snapdragons since the 1990s, explained that these genes work together to fine-tune the pattern that pollinators track.
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