Mongrel fish is a mixture of three species

A GENETIC takeover on a scale never seen before among vertebrates is taking place in the western US. An alien fish is not only hybridising with the locals, but also breaking down the genetic barriers between once-distinct species. Such multiway hybridisation might be much more common than we thought. 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 - two native species, the flannelmouth and bluehead suckers, and one introduced species, the white sucker - as well as hybrids between them. They found that white and flannelmouth suckers breed so extensively with each other that all sorts of genetic intermediates exist; white suckers also occasionally breed with bluehead suckers. The team... [read full story]