The Elements of Evolution (49-11-2) Müllerian Mimicry

 Müllerian Mimicry

In the late 19th century, German biologist Fritz Müller emigrated to southern Brazil and studied the forest there. He observed what came to be called Müllerian mimicry: poisonous species that shared a common predator, mimicking each other’s warning signals. The species involved are not necessarily closely related.

Müllerian mimicry need not involve look-alikes. It may be any sense that a predator employs to select its prey. Many snakes share the same auditory warning signals.

 Tiger Moths

Bats hunt at night via echolocation. Tiger moths are one target. Some of these night-flying moths retain secondary metabolites from eating plants that are baneful to bats. A moth can’t advertise its inedibility to a sightless nocturnal predator by coloration as diurnal insects do. So tiger moths emit warning clicks that tell a bat that they are unpalatable.

Once a bat eats a single toxic tiger moth, that moth is off the menu. Even tiger moth species that are perfectly edible click themselves out of harm’s way.

An edible tiger moth (Bertholdia trigona) has another technique to evade becoming bat fodder: jamming a bat’s sonar with an especially dense series of clicks.