A microbe protects frogs from an infectious one. A lucky frog sits on a leaf in the highlands of Panama. Of all the frogs in its little community, it was one of only a handful that survived a deadly plague. Now, you could think that the frog was innately immune and was able to fight off the potent fungus called Batrachochytrium dendrobatidis. If you thought that, you’d be wrong. The frog wasn’t immune at all, but it did have a guardian, protecting it from the ravages of the plague. It wasn’t an angel guarding the frogs back though: it was…