Masquerading Mayhem - Turning Science on its Head

One of the most interesting concepts of nature and evolution is that of mimicry. An often repeated example is that of the poisonous monarch butterfly (Danaus plexippus) and its mimic the viceroy butterfly (Limenitis arthemis). For many years scientists believed that this mimicry "system" was an example of Batesian mimicry, whereby the coloration of the adult viceroy butterfly was a mimic of the distasteful monarch. Birds would then shy away from eating the viceroy as they did the monarch. Further studies have shown this not to be the case. The findings were published more than a decade ago in the journal Nature: "The viceroy butterfly is not a batesian mimic" by David Ritland and Lincoln Brower [Nature 350:497-498 (1991)].

That study showed that the viceroy butterfly is also distasteful to birds; about as much so as the monarch. Therefore, instead of an example of Batesian mimicry, the monarch-viceroy system is an example of another type of mimicry known as Mullerian mimicry. Mullerian mimicry is where species with similar characteristics, for example the distastefulness of these two butterflies, gain an advantage by their similar appearance. Therefore, if a predator learns not to eat the one species, it will also avoid the second and similar species without having to test it as well.

The correction of our understanding of the monarch-viceroy relationship is an example of our need for scientists to continue their studies in order to unlock the truth about nature and the environment.

To further exhibit the complexity of nature, pictured today is the caterpillar of the viceroy, which is designed to appear as something inedible, perhaps a bird dropping. This form of camouflage is one of the most basic and wide spread types of mimicry in nature.

Today's photograph was taken by WPC Zoologist Ryan Evans this past summer in a Forest County wetland. Ryan is one of the principal staff of the Natural Heritage Program and his responsibilities include projects designed to reveal and assess the animal biodiversity of Pennsylvania and the region.

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