Lipsticks ( Mimulus) are a genus of herbaceous plants. Its representatives grow on harsh, mineral-rich soils and are extremely diverse in shape and flower color, ranging from yellow and pink to deep red. In the process of evolution, some flowers have completely lost their yellow pigments. Scientists from the University of Connecticut (USA) explained what happened to Mimulus at the genetic level and how it affected the evolution of species. The results of the study are published in the journal Science.
Pigments – carotenoids – are responsible for the color of the petals of sponges. About five million years ago, sponges lost yellow carotenoids, but acquired pink ones, attracting pollinating bees. Later, their descendants accumulated mutations in a gene called YUP that restored the synthesis of yellow carotenoids, and mixing pink and yellow pigments led to the formation of red flowers, as the scientists write in their study (although mixing pink and red leads to an orange color. — approx . .ed. ): now they did not attract local bees, but hummingbirds began to pollinate them. As a result, plants with red flowers were genetically isolated and became a separate species.
The YUP gene was found in a region of the Mimulus genome that includes three newer genes not found in other plants. They are copies of genes from other parts of the Mimulus genome . In particular, YUP is actually a partial copy of an ancient gene that was not related to color and pigment synthesis at all.
When the researchers tried to figure out the function of YUP, they found that the gene affects the main regulator of carotenoid synthesis. YUP produced many small RNAs that suppressed the carotenoid gene, which is why yellow flowers completely disappeared five million years ago. The accumulation of mutations blocked the function of YUP and made the synthesis of yellow pigments possible again.
Science knows very few examples of such genes that produce small RNAs that affect traits important for the emergence of a new species. The other two neighbor genes YUP have the same effect on Mimulus coloration . The uniqueness of these three genes, found only in a few closely related Mimulus species , is critical to understanding the formation of new species.
Almost every single species has a small number of genes that are unique to itself. But it was believed that such genes do not make a big contribution to evolution, but it is influenced, on the contrary, by changes in genes common to a large number of different species. The authors of the new study disproved this hypothesis, showing that genes specific to the genus can also become the reasons for the emergence of new species.