The origin of species

Author: John Monczunski

Somewhere Charles Darwin must be smiling over the article that appeared in the February 6 edition of the journal Science. In it, Notre Dame biologist Jeff Feder and his colleagues present evidence that suggests new species may evolve in response to changes in other species. In other words, biodiversity begets biodiversity.

Specifically, Feder and his graduate student Andrew Forbes and their colleagues argue that a wasp that preys on certain flies appears to be evolving in a similar way in response to the fly’s genetic and behavioral change.

Hawthorn flies, scientifically known as Rhagoletis pomenella, historically once mated and laid their eggs exclusively on the fruit and leaves of hawthorn trees. However, some time in the mid-1800s, some of the flies began to prefer apple trees, the ND entomologist notes. Over time the apple-attracted flies have mated more and more among themselves, eventually becoming genetically distinct from their hawthorn-preferring cousins.

Likewise, Feder’s lab has found that a wasp that preys on the fly appears to have altered its behavior in response to the fly, leading to similar changes in its genetic makeup. Just as the flies have begun to diverge genetically into different races, so too have the wasps that prey on them.

“What we see is a chain reaction in which one speciation event creates a new niche, new habitats for others to take advantage of,” Feder observes. “The change is happening right in our own backyards, right before our eyes.”

John Monczunsk is an associate editor of Notre Dame Magazine.