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A small lizard in the Mojave Desert confirmed an evolutionary process proposed more than 100 years ago.
While most of the area's lizards are brown and brown, a population on a parcel called Pisgah Lava Flow is black to match their environment.
This is a phenomenon that has long embarrassed the researchers, as the light-colored lizards that invaded the black lava flow should have survived long enough to evolve this camouflage – but, given the initial contrast, they would have stood out. predators.
Scientists studying lizards have now discovered that the characteristics of animals can change very quickly, allowing them to change their appearance in one life to survive a new environment.
While most area lizards in the area are brown and brown, a population on a parcel called Pisgah Lava Flow is black to match their environment.
"It's an old and very powerful idea, and we now have genetic evidence of how it's going in nature," said co-author Barry Sinervo, professor of ecology and evolutionary biology at the University of California. Santa Cruz University.
The phenomenon is known as "phenotypic plasticity" and refers to the ideas proposed in 1896 by the psychologist James Mark Baldwin. It has since been known as the Baldwin Effect.
"Baldwin has predicted that plasticity allows organisms to colonize new environments and they then develop new adaptations through natural selection," said lead author Ammon Corl, who earned his PhD. in Sinervo's laboratory, and is now at UC Berkeley's Museum of Vertebrate Zoology.
"Until now, however, we lacked genetic tools to show that this was happening on the ground."
The new study documented the process in lizards on Pisgah Lava Flow, revealing how individuals can change color to adapt to their new environment.
According to the researchers, key genes that regulate staining differ between populations on dark lava and on lighter soils nearby.
The team moved lizards between different environments, from sand to dark lava rock, and found that color changes would begin within a week.
Over time, these changes persist until they take over.
"There seems to be a slow, gradual accumulation of dark melanin pigment," said Corl.
In addition to the plasticity found in both populations, the researchers also claim that there are genetic differences in the pigmentation of genes involved in melanin production.
The new study has documented the process in lizards on the Pisgah lava flow. According to the researchers, key genes that regulate staining differ between populations on dark lava and on lighter soils elsewhere in the vicinity.
After crossing the lizards of both populations, the researchers found the variations of these melanin-related genes aligned with the shadow of their skin.
Gene sampling suggests that variants found in the lava population result from mutations, probably thousands of years after the lava flow, 22,000 years ago.
"We've been studying side-lizard lizards everywhere, even in another lava flow, and these genetic variants are only found in Pisgah, so we know where they appeared," Sinervo said.
"These are the genes that govern staining by controlling the production pathway of melanin, but in a complex way.
"Pisgah lizards have the best match to the lava color of all populations, but they can still return to sand and adapt to a completely different environment."
The study now demonstrates the effect Baldwin in action.
"In some ways, it's amazing that natural selection always works in the presence of so much plasticity," said Corl.
"All you need is a bit of a gap and that can make the difference between life and death. There are still variations within the population, so we were faced with natural selection by acting on these genes.
"We can now conduct further field and laboratory studies to better understand how evolution produces highly plastic characters."
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