Ed Yong tells of a case in which a species leapfrogs thousands of years of evolution by getting microbes to do it for them. A certain population of the desert woodrat eats the creosote bush, which contains a deadly toxin, and thrives on it. The woodrats themselves did not develop immunity to the poison, but have gut microbes that break down the creosote. Microbiologist Kevin Kohl ascertained this by comparing desert woodrats who live where the creosote bush grows and woodrats who live where there are no such plants.
To confirm that these microbes are important, Kohl killed them with antibiotics. Afterwards, the woodrats could all still eat normal laboratory chow. But when they were fed with creosote, they couldn’t tolerate the resin and lost a lot of weight. Within two weeks, all of them had lost 10 percent of their weight and were removed from the experiment. When Kohl removed their microbes, the experienced woodrats couldn’t even handle the tiny levels of creosote that their naive cousins can. “[It] effectively removed 17,000 years of ecological and evolutionary experience with creosote compounds,” he wrote.
Conversely, Kohl managed to transform naive woodrats into creosote-busters by infusing them with the microbes of their more experienced cousins. He did this by grinding up the faeces of the experienced individuals and feeding it to the naive ones, mimicking what the rodents naturally do in the wild.
The beauty of this discovery is how one can instantly turn a woodrat into a poison-eating machine just by introducing the right microbe. There are other cases where gut microbes allow an animal to eat something they normally shouldn’t be able to, including commercial livestock. How long will it be before we begin farming all sorts of designer microbes for our own biomes, for purposes we can’t even conceive now? Read more about this research at Not Exactly Rocket Science.
(Image credit: Kohl et al, 2014)