Bacteria blending into single species?

Two bacterial species found in the guts of chickens, pigs and other animals are merging into a single species after the domestication of livestock brought the two microbes together, according to a linkurl:study;http://www.sciencemag.org/cgi/content/abstract/320/5873/237 published today in Science. The research indicates that "despeciation" can be an important consequence of environmental changes in bacterial evolution. Bacteria linkurl:swap genes;http://www.the-scientist.com/blog/display/54429/ so often that it can be difficult to define species boundaries and determine the mechanisms that drive bacterial linkurl:speciation.;http://www.the-scientist.com/article/display/14251/ Nonetheless, biologists commonly distinguish bacterial species based on limited gene flow. The two pathogens, Campylobacter jejuni and Campylobacter coli, which live in the digestive tracts of many animals and are major causes of human gastroenteritis, are indeed recognized as distinct species — their nucleotide sequences have diverged by about 13%, suggesting that the two species probably split over 100 million years ago. Now, however, researchers at the University of Oxford have a linkurl:gut;http://www.the-scientist.com/news/display/23519/...