On his website Evolving Perspectives, Reader Pliny the In Between—perhaps inspired by yesterday’s posts on mimicry and Alabama’s banning of sex toys—has created this nice cartoon that he calls “Batesian mimicry”.
A biological digression:
Now if you don’t understand the title, Batesian mimicry is an evolutionary phenomenon whereby a conspicuously colored or patterned toxic individual, called a “model,” is avoided by its predator, who has learned to avoid the pattern lest it be stung, bitten, or poisoned. (The learning predator is called the “signal receiver”.) Many conspicuously colored insects, for example, like ladybird beetles (“ladybugs”) or monarch butterflies, are brightly colored and patterned because they are toxic and distasteful. It’s a bit of a mystery how these warning colors and patterns (called “aposematic”) evolved, since the first conspicuous mutant, even if toxic or distasteful, would call attention to itself (the predators hadn’t year learned), risking a higher chance of being attacked. One possible solution is kin selection.
Nevertheless, once the model has evolved aposematism, and there are predators who have learned to avoid it, then there is an evolutionary advantage for a nontoxic species (called a “mimic”) to evolve a resemblance to the model, thereby gaining respite from predation based on the predator’s learned avoidance.
The phenomenon was named after the British naturalist and explorer H. W. Bates (1825-1892), who, in his travels in South America, saw such mimics and devised the correct evolutionary explanation. He, like his co-explorer Alfred Russel Wallace (with whom Bates traveled in 1848), was a great fan and promoter of Darwin’s theories of evolution and natural selection. In fact, Batesian mimicry served as some of the earliest evidence for natural selection, as the system is easily explained by natural selection while creationists are forced to concoct ad hoc arguments.
Here’s a good example of a Batesian mimic: a moth, perfectly edible to birds, that is avoided because it resembles a hornet. I was once fooled by a similar moth that invaded my home in Maryland. This one is Sesia apiformis, taken from the UK Moths website:
You’d avoid that if you saw it, wouldn’t you?
Pliny cleverly called his cartoon “Batesian mimicry” because the pair of women “proselytizers” are, while mimicking the unpalatable pairs of Mormons or Jehovah’s Witnesses who visit homes, actually quite innocuous themselves.