London, July 22 : The Colorado River basin in the south-western US is witnessing multi-way hybridization, thanks to an alien fish, which is breaking down the genetic barriers between once-distinct species.
Dave McDonald, an evolutionary biologist at the University of Wyoming in Laramie, and his colleagues sampled DNA from three species of fish in the Colorado river basin in the south-western US.
The fish studied were two native species, the flannelmouth and bluehead suckers, and one introduced species, the white sucker - as well as hybrids between them.
According to a report in New Scientist, the researchers found that white and flannelmouth suckers breed so extensively with each other that all sorts of genetic intermediates exist; with the white suckers also occasionally breeding with bluehead suckers.
The team also found another sort of fish, which they dubbed the "muttsucker" - a hybrid containing genetic material from all three original species.
Since bluehead and flannelmouth suckers have never been reported to cross-breed on their own, it seems that introducing the white sucker acts as a genetic bridge to break down the barriers between these two native species.
If this process continues, the gene pools of the three species could eventually merge into a single, indistinct "hybrid swarm", which may eventually pull in other native suckers as well.
"If so, this introduced species isn't going to wipe out just one native. It's taking out a whole assemblage of native species," said McDonald.
According to Ole Seehausen, an evolutionary ecologist at the Swiss Federal Institute for Aquatic Science and Technology in Kastanienbaum, McDonald's is the first published study to report solid evidence of three-way hybrids in vertebrates.