New research on pepper moths has shown that their ability to evolve and camouflage themselves is what has allowed them to survive.
While it may be a contentious issue for some, scientists have just produced a new study on “Darwin’s moth” that confirms evolution by natural selection.
In their new research, scientists were able to demonstrate clearly that dark and light varieties of the peppered moth known as Biston betularia were only able to survive if they were adequately camouflaged from birds, as Phys.org has reported.
“Industrial melanism — the prevalence of darker varieties of animals in polluted areas — and the peppered moth provided a crucial early example supporting Darwin’s theory of evolution by natural selection, and has been a battleground between evolutionary biologists and creationists for decades.”
The most prevalent of these moths is normally protected and adequately camouflaged by lichen that appears on the bark of trees, yet at the time of the Industrial Revolution much of this lichen was wiped out with dark soot covering the bark of many of these trees, which led to the more recent emergence of a much darker variety of this moth.
Thanks to clean air legislation in the U.K., much of the lichen has now reappeared, and with this has come the return of light pepper moths. Despite numerous studies, up until now, scientists had not examined how the camouflage of these moths helped to influence and determine their survival.
Scientists working at the University of Exeter have now researched the matter thoroughly, and have determined that the lighter moths are actually much better at camouflaging themselves around lichen on trees than their darker counterparts, showing that evolution is responsible for their survival, according to Professor Martin Stevens.
“This is one of the most iconic examples of evolution, used in biology textbooks around the world, yet fiercely attacked by creationists seeking to discredit evolution. Remarkably, no previous study has quantified the camouflage of peppered moths, or related this to survival against predators in controlled experiments.”
Professor Stevens explained that by employing the use of digital image analysis, scientists were able to understand how well birds were able to see both the light and dark pepper moths.
“Using digital image analysis to simulate bird vision and field experiments in British woodland, we compared how easily birds can see pale and darker moths, and ultimately determine their predation risk.”
“Our findings confirm the conventional story put forward by early evolutionary biologists — that changes in the frequency of dark and pale peppered moths were driven by changes in pollution and camouflage,” Professor Martin Steven further noted.
Unlike humans, birds are aware of ultraviolet light and also see many more colors than we do, and with this information scientists looked at just how good both light and dark pepper moths were at hiding themselves against lichen on trees, as well as trees that were bare.
According to lead author Olivia Walton, birds are much less likely to notice the lighter moths when perceived near lichen-covered trees.
“Through a bird’s eyes, the pale peppered moths more closely match lichen-covered bark, whereas darker individuals more closely match plain bark. Crucially, this translates into a strong survival advantage; the lighter moths are much less likely to be seen by wild birds when on lichen-covered backgrounds, in comparison to dark moths.”
The new study which shows evolution and natural selection in action when comparing the survival rates of light and dark pepper moths has been published in Communications Biology.
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