SCIENCE
03/16/2013 08:23 am ET Updated Mar 16, 2013

Dust Mites Study Shows Reversible Evolution Is A Reality & Contradicts 'Dollo's Law'

An often-despised common household pest may have disproven a deeply rooted biological principle -- the idea that, as far as evolution is concerned, you can't go backward.

Who's the culprit? The lowly dust mite. By examining and mapping out the phylogenetic tree of the mite in a new study, researchers at the University of Michigan in Ann Arbor have found that evolution is reversible.

The idea has always been "once a parasite, always a parasite," study co-author Dr. Barry OConnor, a professor at the university's Department of Ecology and Evolutionary Biology, told The Huffington Post. But his recent study suggests otherwise.

With the help of other biologists around the world, Oconnor and his research team looked at about 700 mite species. They then sequenced five nuclear genes from the species and created a sort of mite family tree.

The researchers found that free-living dust mites evolved from parasitic mites, which themselves were originally free-living organisms. This, OConnor said, is "conclusive evidence" that reversal is possible.

He said, in his opinion, the research shows reversible evolution is possible on a complex ecological scale.

This conclusion of the study contradicts the 120-year-old principle known as Dollo's law, which essentially states evolution is not reversible.

Yet, in addition to its academic and theoretical applications, the study's conclusion may have a more practical use: A better understanding of dust mites may help scientists find ways to aid the up to 1.2 billion people who are allergic to the pesky, ubiquitous creatures.

This result was so surprising that we decided to contact our colleagues to obtain their feedback prior to sending these data for publication,” study co-author Dr. Pavel Klimov, an assistant research scientist in the university's Department of Ecology and Evolutionary Biology, said in a written statement. “Parasites can quickly evolve highly sophisticated mechanisms for host exploitation and can lose their ability to function away from the host body. Many researchers in the field perceive such specialization as evolutionarily irreversible.”

Some colleagues have yet to completely warm up to the study's idea. "Are we being laughed at by people? No," OConnor told HuffPost. "It's only some folks who aren't being flexible."

The study, "Is Permanent Parasitism Reversible? -- Critical Evidence from Early Evolution of House Dust Mites," published online March 8 in the journal Systematic Biology.

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