Charles Darwin logic doesn't pan out

Eric Sorensen, WSU News

PULLMAN, Wash. – For more than a century and a half, researchers interested in invasive species have looked to Charles Darwin and what has come to be called his “naturalization conundrum.” If an invader is closely related to species in a new area, he wrote in his landmark “The Origin of Species,” it should find a more welcoming habitat. On the other hand, it could expect to compete with the related species and be vulnerable to its natural enemies.

Species vs. details

But researchers writing in the latest issue of the Proceedings of the National Academy of Sciences say the relatedness of new and established species is not as important as the details of how they go about doing their business.

“We thought we understood how things happened, but maybe they happened for another reason,” says Emily Jones, a Rice University researcher in evolutionary ecology who started pondering Darwin’s conundrum while a post-doctoral researcher in the Washington State University lab of Richard Gomulkiewicz. She is the lead author of the Proceedings paper with Gomulkiewicz and Scott Nuismer of the University of Idaho.

Darwin’s logic doesn’t pan out

“Darwin put out a lot of interesting ideas back in the day but he didn’t have the means to check them with rigor,” says Gomulkiewicz, a professor in WSU’s School of Biological Sciences. “That’s what we did with our mathematical model, and we found that Darwin’s logic on this issue doesn’t quite pan out.”

The model they’ve developed in analyzing Darwin’s conundrum could lead to a new way of gauging the potential of invasive species, a major ecological and economic concern as plants and animals have spread into new habitats around the planet.

Genetics alone a weak predictor

Darwin focused on phylogeny, species’ relatedness or genetic similarity. But Jones and her colleagues focused on species’ phenotypes, characteristics that emerge as a plant or animal’s genes interact with the environment. In the process, they found that genetic relationships alone are a weak predictor of an invaders success.

To be sure, says Jones, researchers will want to see what species an invader is related to and what interactions that species has that are important for understanding its survival.

But then, she says, “you’d want to look at how those interactions depend on traits and affect births and deaths in the invading species.”



Richard Gomulkiewicz, 509-335-2527,

Emily Jones, 713-348-4182,