Monday, December 19, 2011


Just received an interesting e-mail from Dr. Eugene Morton, head of the Hemlock Hill Biological Research Station outside Cambridge Springs, Pa. He recently read that the viceroy is NOT a mimic of the monarch, as he so believed for decades!

The Monarch Butterfly (Danaus plexippus) is a member of a Müllerian complex with the Viceroy butterfly (Limenitis archippus) in shared coloration patterns and display behavior. A bit about Müllerian mimicry- what is it? According to Wikipedia, it describes a situation where two or more species have very similar warning signals and both share the common anti-predation attribute- they're  unpalatable. A scientists named Dr. Henry Bates questioned how or why this mimicry existed. If both butterfly species were harmful, then why did one need to mimic another? The German naturalist Fritz Müller put forward the first explanation for this phenomenon: If two species were confused with one another by a common predator, individuals in both would be more likely to survive.

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This type of mimicry is unique in several respects. Firstly, both the mimic and the model benefit from the interaction, which could thus be classified as mutualism in this respect. The signal receiver is also advantaged by this system, despite being deceived regarding species identity, as it avoids potentially harmful encounters. The usually clear identity of mimic and model are also blurred. In cases where one species is scarce and another abundant, the rare species can be said to be the mimic. But, when both are present in similar numbers, it is more realistic to speak of each as co-mimics than of a distinct 'mimic' and 'model' species, as their warning signals tend to converge toward something intermediate between the two. Also, the two species may exist on a continuum from harmless to highly noxious, so Batesian mimicry grades smoothly into Müllerian convergence.

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The Viceroy has subspecies with somewhat different coloration, each one very closely matching the local Danaus species. E.g., in Florida, the pairing is of the Viceroy and the Queen Butterfly, and in Mexico, the Viceroy resembles the Soldier Butterfly. Therefore, the Viceroy is a single species involved in three different Müllerian pairs. This example was long believed to be a case of Batesian mimicry, with the Viceroy being the mimic and the Monarch the model, but it was more recently determined that the Viceroy is actually the more unpalatable species, though there is considerable individual variation. While L. archippus is really bad-tasting, Danaus species tend to be toxic rather than just repugnant, due to their different food plants.

We must continue to learn, and to discard the untruth...