By Susan Milius
A recently criticized textbook example of evolutionary forces in action, the dark forms of peppered moths that spread with industrialization in Britain, may be on its way back.
Results of an ambitious experiment on the moths (Biston betularia) support the original hypothesis that their dark-colored forms spread in soot-coated landscapes because they are more difficult for hungry birds to spot, says evolutionary biologist James Mallet of Harvard University. He and three colleagues have published the final peppered moth experiment of Michael Majerus, who spent six years monitoring the fates of a total of 4,864 moths, presented his conclusions at a conference but died before publishing them. The study appears online February 8 in Biology Letters.