A research team led by Professor Barry OConnor and Dr. Pavel Klimov has used a large-scale genetic study of the house dust mite to uncover an example of reversible evolution that appears to violate a deeply rooted supposition that evolution is unidirectional and irreversible, dubbed Dollo's law.

But this "law" is not universally accepted and is the topic of heated debate among biologists. The study shows that tiny free-living house dust mites, which thrive in the mattresses, sofas and carpets of all homes, evolved from parasites, which in turn evolved from free-living organisms millions of years ago.

"All our analyses conclusively demonstrated that house dust mites have abandoned a parasitic lifestyle, secondarily becoming free-living, and then speciated in several habitats, including human habitations," according to Klimov, first author and an EEB research scientist and OConnor.

Their paper, "Is permanent parasitism reversible?--Critical evidence from early evolution of house dust mites," was published online March 8, 2013 in the journal Systematic Biology.

The story has been widely covered in the media including this Discover magazine blog article, The New York Times Science section, and in Newsweek/The Daily Beast.

U-M News Service press release

Watch for an EEB research feature coming soon

Caption: A scanning electron microscope image of an American house dust mite. Image credit: G. Bauchan and R. Ochoa.