Kevin Kohl/Univ. of Utah
Packrats can repeatedly eat poison if they have the right gut microbes.
Scientists had suspected this, but there wasn't much evidence to support the idea, so a team decided to test it in desert woodrats (Neotoma lepida). Some populations of this species snack on a bush called creosote, which is toxic, while other groups leave it alone. When the creosote-eaters were given antibiotics, their gut microbes changed so that they couldn't metabolize the toxins from bush. And when non-creosote-eaters were given fecal transplants from those that could eat the bush, the non-eaters could ingest more of the toxin.
The results, published July 20 in Ecology Letters, suggest that gut microbes expand the range of what planting-eating mammals can munch on and that microbes may one day help livestock broaden their menu too.