"BORDENSTEIN: So the hologenome theory is in its early days, and it’s arguably something that will have a lot of questions around it. Conceptually, the two founders of the hologenome theory, Richard Jefferson and Eugene Rosenberg, have come up with the description of the theory. And Eugene Rosenberg's lab from Israel has found that if you take a single species of fly, the same species, and you split that species and cultivate it on two different diets, and then you bring these flies back in contact with each other and ask, “do they mate?” , they stunningly found that these flies didn't mate when they were reared on different diets, but yet they were considered the same species. They were able to find that it was the bacteria in their guts that changed that helped contribute to this mating discrimination that they saw in this one species."

via "Microbes and Evolution"
how gut bacteria influence evolution
Living on Earth