Charles Darwin has had a remarkable record over the past century, not only in the affirmation of evolution by natural selection, but in the number of his more specific ideas that have been proved correct.

He may, however, have been wrong about invasive species, at least where amphibians are concerned. Darwin believed that when an invasive species entered a region where a closely related species already existed, it would most likely be unsuccessful because of a competition for resources.
“Instead, we found the opposite pattern with amphibians,” said Reid Tingley, a biologist at the University of Sydney in Australia. “When frogs and toads and salamanders invade an area where a similar species exists, they are more, not less, likely to establish themselves.”
He and his colleagues report their findings in the March issue of The American Naturalist.
This is the first study that contradicts Darwin’s invasive species hypothesis using animals. Previous studies using plants have produced mixed results, Mr. Tingley said.
The researchers analyzed a large database containing information on amphibians that had been introduced outside of their native ranges.
They studied 521 successful introductions that took place from 1696 to 2006. About 55 percent of the introductions occurred after 1900, when travel and trade began to increase across nations and continents.
One explanation as to why the amphibians seem to thrive when introduced in locations with related species is that there is a natural suitability. When close relatives are already doing well, it’s a positive sign, Mr. Tingley said.
The amphibians studied were primarily in North America and Europe, but included species in Asia, Africa and Australia as well. “It was not only a very large taxonomic scope, but a very large geographic scope,” Mr. Tingley said. “And we still find the same effect throughout.”
The findings could help conservationists predict the risk levels of introducing specific alien species into a region, the researchers suggest.
(Source: The NYT)