They identify new color patterns in the desert from the gaze of pollinators

Thanks to the rains that fell this winter, the Atacama Desert became a true spectacle, with multiple and colorful flowers that grew in the middle of this particular territory, the second most arid on the planet, after the polar ecosystems.

Every time this sporadic phenomenon occurs, there are many and varied species that appear, among them, cistanthe longiscapa, the same one that generated great curiosity in a group of Chilean researchers, who in October 2021 observed how these flowers had new and strange color patterns. In a sector to the north of Caldera, this native plant, popularly known as guanaco pawhad grown in different patches of purple and yellow flowers, among which were also numerous shades in between: reddish, pink, and white.

Following the discovery, scientists Jaime Martínez-Harms, from the Institute for Agricultural Research, INIA, and Pablo Guerrero, a researcher at the Institute of Ecology and Biodiversity (IEB) and the University of Concepción, studied the ecological and evolutionary mechanisms that generated this diversity of colors and visual patterns in an extreme environment such as the Atacama Desert, and how pollinators perceive this variability.

The work, recently published in the scientific journal Frontiers in Ecology and Evolutionalso included the participation of María José Martínez-Harms, an IEB researcher, among other Chilean scientists, from the Netherlands and New Zealand.

Studying the diversity of colors

“In this place near Caldera, I was struck by the fact that there were two very distinctive separate flower patches, one yellow and the other pink, and that in the areas where these were found there was a greater abundance of unusual colors in cistanthe. This is where the idea of ​​characterizing the colors of these flowers arose with a modified camera to expand its sensitivity and a spectrometer. As we began to evaluate colors, we saw that in addition to differences in the range of colors visible to humans, there were differences in the ultraviolet range. And that is very interesting, because pollinators, generally birds and insects, unlike us, do perceive colors in that range of the light spectrum”, explains Jaime Martínez-Harms.

Pablo Guerrero explains that polymorphisms in nature, that is, differences in physical characteristics between individuals of the same species, are the raw material of evolution. “Variability within each species is a fundamental dimension of biodiversity. These polymorphisms in plants occur due to the interaction with their pollinators”, points out the researcher from the IEB and the University of Concepción.

To understand these interactions, the research also incorporated a landscape ecology approach, led by María José Martínez-Harms, director of the IEB’s Ecosystem Conservation and Human Well-being Laboratory. “My role was to address this variability of colors considering the scale of the landscape, which can have an impact on the resilience and adaptive capacity of ecosystems”, explains the researcher.

The researchers emphasize that these color changes account for historical processes and in this context, what we see today is the result of changes that may have occurred tens, hundreds or thousands of years ago, giving rise to morphologies that can sometimes be highly specialized for certain pollinators of the flowery desert.

Watching the desert like a pollinator

What results did you get from this particular visual spectacle and the field and laboratory analyses? How do pollinators, mainly solitary wasps and bees, perceive the colors of Cistanthe flowers and their differences?

According to the study, this variability of colors in guanaco legs is due to the generation of different pigments in the flower petals, called ‘betalains’, which in turn are known to provide protection to plants against drought, salt stress and other environmental factors.

This colorful desert festival is perceived differently by humans and pollinators, as pollinators can see a different range of colors than we do.

To understand this, the study looked at flowers from the perspective of a pollinator, specifically, the honey bee. For the study, the scientists considered the color perception of bees, who have three types of light receptors in their eyes, sensitive in the ultraviolet, blue and green light ranges, respectively. The results show that these insects are capable of perceiving a greater diversity of colors in this species of plant than humans, who have receptors sensitive to blue, green and red, but not to ultraviolet.

In the case of these flowers, Hymenoptera, just like us, can easily distinguish between red, pink, white and yellow variants. But they can also differentiate between flowers that reflect ultraviolet light, from those that have little or no UV, variants present in yellow and pink flowers. Likewise, there is in some flowers what is called a “bull’s eye” pattern, a kind of ultraviolet mark that guides pollinators towards nectar and pollen, which is invisible to us.

According to the authors, the chromatic variation of these flowers, would also be related to different pollinating insects, through their preference for flowers with particular color and shape patterns, would encourage these variants to isolate themselves reproductively from other individuals of the same plant species, a process that could give rise to new races or even species.

“We believe that this color variability could help ensure the reproduction of these plants, considering that the flowering desert events are short and sporadic. This variability is very important because it tells us that in order to ensure the conservation of these species it is important not only to look at the species as a whole, but also to protect each of its variants”, points out Jaime Martínez-Harms.

supporting conservation

Both Pablo Guerrero and María José Martínez explain that understanding these interactions that occur in the Atacama desert, addressing perception and ecology together, is important to advance not only in the generation of scientific knowledge, but also in the conservation of this particular ecosystem.

“The Atacama desert is a true research laboratory on our biodiversity, and therefore the relevance of developing these studies. It is very interesting to communicate to society that not all of us perceive the world in the same way, as happens with some pollinators. It is key to highlight that initiatives such as the creation of the “Desierto Florido National Park” can be very relevant to conserve this heritage of biodiversity, which has an uncertain future due to the impacts of climate change, land use change, pollution and other human actions. . We must support conservation actions for our biodiversity, since it not only has a value in itself, but is also life and resilience insurance for people and nature”, explains María José Martínez.

Pablo Guerrero highlights the relevance of the desert and its biodiversity, both visible and invisible. “Nature brings numerous benefits to people. However, much of the biodiversity is not always seen by our eyes. Nocturnal species or those that are scarce, can remain hidden for years underground, in the form of seeds. Therefore, conserving these ecosystems, beyond the obvious, has tremendous ecological and social value, which we should further promote through science and various environmental education initiatives”, concludes the IEB scientist.