It looks like there will be a bit of biology today, which is a relief to me (and maybe others) given the impending dissolution of our Republic. There are two quiz questions in this post; see if you can answer them in the comments.
I’ve posted a bit on Batesian mimicry, in which a noxious species (called the “model”) is avoided by a predator, often because it has bright colors or patterns that call attention to it (“aposematic coloration”). Models who are avoided by predators include bees, wasps, and some foul-tasting butterflies like the Monarch (see earlier post). When a predator has learned to avoid a particular pattern because it’s associated with toxicity or distastefulness—and this means that that predator has to have had at least one experience with the model to induce learning—this gives an evolutionary opening for a non-toxic or tasty species to evolve a resemblance to the model. These species, called “mimics”, experience selection for that resemblance because the more you resemble a model that’s already avoided by a predator, the greater chance you have of surviving and passing on your genes—thus enriching the mimic gene pool in those genes that make them look like models.
Here’s one example of Batesian mimicry (named after the naturalist Walter Henry Bates who described the phenomenon): the nestlings of the bird Laniocera hypopyrra, the “cinerous mourner” in Peru. This is bizarre because the baby birds resemble, both in behavior and appearance, a toxic caterpillar that lives in the same area. Read my post on this amazing resemblance. (This is not 100% confirmed as a case of Batersian mimicry, but it looks pretty good):
You can find my other posts on Batesian mimicry here.
The other classic form of mimicry is called Müllerian mimicry, named after the German biologist Fritz Müller, who described the phenomenon. In this case a number of distasteful, dangerous, or toxic species come to resemble each other because it facilitates predator learning. By that I mean that the more individuals of different species who have been sussed out as bad by predators come to resemble each other, the greater protection they’ll enjoy, as the different species with similar appearances will cause the predator to learn even more strongly. (Quiz question #1: given two toxic aposematic species that look different and are already avoided by predators, why would it be advantageous for a single mutant individual of one species to resemble members of the other species?)
In Müllerian mimicry, both species are models and mimics at the same time. There are lots of cases of Müllerian “mimicry rings” in which very unrelated species come to adopt similar colors and patterns: these rings can involve moths, beetles, butterflies, true bugs, and so on—all looking similar. They must, of course, live in the same place, for to evolve the system requires a predator that encounters all the species—just as in Batesian mimicry, where both model and mimic must live in the same place (there are a few exceptions: see quiz question at bottom).
Here’s a new tw**t by naturalist and photographer Piotr Naskrecki showing three beautiful Müllerian mimics: members of the Ampulicidae (tropical “cockroach wasps”), Apidae (various kinds of bees), and Chrysididae (“cuckoo wasps”). All are dangerous to predators (they sting), and all have similar, obvious metallic-green coloration. This can be considered a mimicry ring, and I suspect they all share at least one potential predator (probably a bird).
Here’s Quiz Question #2: there are a few cases of Batesian mimicry in which the model and mimic live in different places. How do you suppose that could happen?
h/t: Matthew Cobb, inveterate Twitter-scanner