Organisms that have adapted by losing genes and traits

Sometimes Devolution offers an advantage

Armed with the Amanita mushroom family tree, Evolutionary Biologists Pringle and Wolfe were able to determine that Amanita evolution has largely been away from species that help decompose organic material and toward those that live symbiotically on trees and their roots. More interestingly, they found that the transition came at a steep price -- the loss of the genes associated with breaking down cellulose.

"There had been earlier suggestions that this type of gene loss might be taking place, but our study is the first precise test of that hypothesis," Ultimately, Pringle said, the paper highlights one reason she finds such symbiotic partnerships "intrinsically interesting" -- for all their apparent benefits, the cost can be high.

"I think the really interesting thing is this idea that once you become symbiotic, some of your machinery is lost," she said. "It seems like a dead end in some ways -- you have to make this change to enter this niche, but once you're there, you can't go back -- you've lost the capacity to be free-living."