Diversity of desert flowers is determined by pollinators • Earth.com

Although the Atacama Desert, which stretches 1,600 kilometers along the west coast of South America, is the driest place on Earth, it is far from arid. Many plant species adapted to extreme conditions thrive there. In addition, approximately every five to ten years, this desert is home to one of the most spectacular sites in the world: the so-called “florida desert” (“flowering desert”) – amazing mass blooms of flowers that usually occur after rain.

Now, an international team of scientists has investigated what physiological and evolutionary mechanisms enable the great diversity of flower shapes, colors and visual patterns over the course of floridos desertsand how the pollinators for whose benefit such visual extravagance has evolved perceive these variations.

“Our goal was to shed light on the ecological and evolutionary mechanisms that cause biological diversity in extreme environments like the Atacama Desert,” said the study’s first author, Jaime Martínez-Harms, a researcher at the Agricultural Research Institute in Chile.

“Here we show that pussy flowers Cistanthe longiscopa, a representative species for floridos deserts in the Atacama Desert, are highly variable in the color and patterns they present to pollinators. This variability probably results from different so-called “betalain” pigments in the flower petals.

During floridos deserts, C. longiscopa – an annual plant up to 20 centimeters that blooms in patches of purple and yellow flowers, with numerous intermediate flowers (reddish, pinkish, white) in between – seems to be the dominant species in the Atacama Desert, suggesting that the purple and yellow morphs are inherited variants that can be crossed.

In order to clarify how pollinators – mainly hymenoptera such as wasps and bees – perceive these flowers, the scientists used visible-light and UV-sensitive cameras, as well as spectrometers to measure the reflection, the absorption and transmission of different wavelengths of 110 violet, yellow, pink and while C. longiscopa flowers, which helped them create composite images of these variants seen by various pollinator species.

The results showed that the diversity perceptible to pollinators was greater than what the human eye can perceive, since these insects can also distinguish flowers with high or low UV reflectance.

According to the researchers, the visual diversity of the flowers is due to the differences between the betalains (yellow, orange and purple pigments) which not only give the flowers their colors, but also protect them from drought, salt stress and damage caused by the sun. reactive oxygen. radicals under environmental stress. Moreover, this diversity appears to be driven by differences in sensitivity and preference for different colors and patterns among various pollinator species.

“The great variation in the color of the flowers within C. longiscopa can be explained if different species of pollinating insects, through their preference for particular flower colors and patterns, could lead to the reproductive isolation of these variants from other individuals of the same plant species. This ongoing process could ultimately lead to the origin of new races or species,” Martínez-Harms said.

“In our next studies, we will further investigate the chemical identity and biological synthesis pathways of betalains and other floral pigments, as well as their relationship to traits such as fragrances produced by flowers. This should help us understand their role in shaping plant-pollinator interactions, and in plant tolerance to biotic and abiotic stressors under fluctuating climatic conditions,” he concluded.

The study is published in the journal Frontiers in Ecology and Evolution.

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By Andrei Ionescu, Terre.com Personal editor

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