The fascinating evolutionary history of Eriosyce chilensis, the endemic cactus that survives in just 10 kilometers of the Chilean coast. Threatened by illegal trade and urban expansion, this cactus holds a unique tale of adaptation in its pollination. Here we tell you how nature and its pollinators wrote their own evolutionary history.

On the coastal cliffs between Pichidangui and Los Molles, an evolutionary tale is silently written. Here, in just 10 kilometers, lives the Eriosyce chilensis cactus, a unique species in the world that has captured the attention of science for its evolutionary history.

Fortunately, local organizations and the Puquén Bio Park are working in this area on the conservation of native flora and environmental education. “It is essential to raise awareness in communities, especially among young people. They are the ones who will have to take care of these unique ecosystems on the planet,” emphasizes Martínez-Harms, one of the co-authors of a recent scientific publication addressing this topic.

Jaime Martínez-Harms, a biologist with a PhD in natural sciences from INIA La Cruz, along with specialist Dr. Pablo Guerrero from the Institute of Ecology and Biodiversity (IEB), and other experts from various research centers, studied how this species has modified its pollination strategy, shifting its dependence on hummingbirds to native bees.

The area that houses Eriosyce chilensis is recognized as an AZE (Alliance for Zero Extinction) site, a global conservation hotspot for hosting the last remaining populations of critically endangered species. Furthermore, it is an area of ​​high real estate pressure, a constant threat from illegal cactus extraction, clandestine micro-dumps, and an irregular trade that extends even to Europe and Asia.

In this small space, two sister cacti coexist: Eriosyce litoralis and Eriosyce chilensis. Eriosyce litoralis offers tubular flowers with nectar that attract hummingbirds, while Eriosyce chilensis has open flowers with little nectar but abundant pollen, which are attractive to native bees.

Interestingly, in this shared environment, these sister species remain reproductively isolated thanks to pollinators. Bees and hummingbirds act as natural reproductive barriers, preferentially choosing flowers with characteristics that are most attractive to them. "The chilenito is an example of how pollinators, through their behavior, can influence the evolution of flower traits. In this case, bees and hummingbirds may have promoted the formation of a new species," says researcher Martínez-Harms.

One of the most fascinating aspects is the color transition in the flowers of Eriosyce chilensis, from intense fuchsia tones in Los Molles to almost white tones in Pichidangui, resembling Eriosyce mutabilis. On this point, the expert specifies, “the study proposes that E. chilensis would have evolved by adopting the shape and color of this third species, E. mutabilis, which is also pollinated by bees.” This gradient, he explains, “could respond to selective pressure from pollinators, showing how small changes in ecological interactions can have significant evolutionary consequences.”

While this change could respond to a phenomenon of floral mimicry, where the new species adopts traits from an already established species to attract pollinators, this colorful gradient reflects a complex process of ecological adaptation.

This study not only expands knowledge about the biology and ecology of these coastal cacti but also provides keys for their conservation, especially in a context of climate change and increasing loss of natural habitats.

For Martínez-Harms, this case “is a valuable example of sympatric speciation, a fascinating process, and a unique opportunity to understand how plant-pollinator interactions shape biodiversity.” Furthermore, it highlights the urgent need to preserve these biological relics and their environment, not only for their uniqueness, but also for the knowledge they contribute to science and humanity.