Monarch Mimicry Complex

Monarch

The bright orange Monarch (Danaus plexippus), Queen (Danaus gillipus) and Soldier (Danaus eresimus) butterflies are all members of the Danaus genus of butterflies. It is often hard to tell the difference between these species here in Florida because they look so much alike. This is not an accident but a marvel of evolution called mimicry that helps to protect them from predators.

Mimicry occurs when one group of organisms (mimics) evolves to share perceived characteristics with another group of organisms (models) through selective actions. In other words, one species shares physical similarities with another in order to protect them both.

Soldier

Monarchs, Queens, and Soldiers are not tasty to predators. Also known as Milkweed butterflies, each of these species consumes milkweed as a host plant. Members of the Milkweed (Asclepias) genus of plants contain a milky latex sap that is toxic or noxious to many predators. Caterpillars that consume the sap-filled leaves of milkweed plants take those toxins into their bodies which, in turn, makes them taste very bad.

As adults, the Monarch, Queen and Soldier butterflies are clever mimics utilizing a special form of mimicry called Müllarian Mimicry to reinforce the warning colors and distasteful qualities of these related and similar looking species. This mimicry gains all three species more protection from predators.

Monarch (L); Queen (R)

How Does It Work? 
A bird that tastes a monarch will learn and remember that the bright orange coloration and pattern of decoration on a monarch butterfly is a signal of unpalatability. A queen butterfly flying past later will likely be viewed as 'not food' since it bears such a striking resemblance to a creature which tasted very bad to the bird. Thus the two species gain an advantage against predators by each offering the same bad taste to the predators and reinforcing that bad taste with a very similar appearance.

Müllarian Mimicry and Fritz Muller

Muller

Johann Friedrich Theodor Müller (March 31, 1821 – May 21, 1897), better known as Fritz, was a German biologist and physician who emigrated to Brazil and spent his life studying the sub-tropical Atlantic forests south of Sao Paulo. Müller's discovery in the field of mimicry concerned resemblences between unpalatable species which helps to protect those species from predators capable of learning.

We can see Monarch, Queen and Soldier butterflies in Florida. All three species consume milkweed and sequester toxins from the plants in their bodies, making them distasteful to predators such as birds. All three species utilize an aposematic or warning coloration of bright orange and red tones that generally warn of toxic qualities in prey. These three species resemble each other so strongly that they are often misidentified by people and by predators.

The Florida Viceroy: A Co-Mimic

Viceroy

The Viceroy (Limenitis archippus floridensis) butterfly is a Mullerian co-mimic of the Danaides milkweed butterflies. Where the milkweed butterflies sequester toxins from their milk sap host plant Milkweed, the Viceroy butterfly sequesters salicylic acid from its host which also makes the Viceroy distasteful to predators, just using another chemical. By each resembling the other, the Viceroy butterflies and the Danaides species help to reinforce their coloration and patterns as toxic to predators, helping all species in the mimicry complex gain more protection.

Etymology of Mimicry 
 mimetic 1637, "having an aptitude for mimicry," from Gk. mimetikos "imitative," from mimetos, verbal adj. of mimeisthai "to imitate." Originally of persons, attested of animals or plants from 1851. Online Etymology Dictionary