If you saw these in the wild you'd probably want to steer clear, but the truth is, only
one of these is a real bee. The rest are harmless flies. Mimics of a model. Can you guess which
one is the real one?
Perhaps you found it pretty easy and found it right away, or maybe you were tricked by
their disguise.
[INTRO by Caro Waro & Cristina de Manuel]
The mimic flies do a relatively good job of imitating the patterning, the body shape
and in some cases even the behaviour of the bees.
Bees use bright contrasting colours such as yellows, reds and black to signal that they
are of no interest to any predators. This is known as aposematism and many different
insects find themselves converging on a similar model of signalling. This is known as Mullerian
mimicry and it's a form of honest signalling because all of them are sending the same honest
message to a potential predator: "WE ARE NOT GOING TO TASTE GOOD".
The mimic flies are exploiting are form of dishonest mimicry known as Batesian mimicry,
because they are piggybacking off the protection that's conferred by looking like an animal that
is distasteful but without having to go through the cost of having a sting, or producing the
compounds for a bad taste.
Mimicking a poisonous or distasteful animal is actually quite a clever strategy provided
there are sufficient models around that a predator is likely to encounter it and associate
that patterning with bad taste - meaning that they are going to be avoided in the future.
However, something that often puzzles scientists is that many mimics are actually very poor
copies of the real thing, and there are quite a few hypotheses out there that aim to explain
this.
Some of the evolutionary hypotheses state that perhaps the mimics just haven't had enough
time to converge on the model or perhaps the model and the mimic are engaged in an evolutionary
arms race, whereby the model is also under pressure to evolve away from the mimic.
However, these theories have two very big caveats: first of all, they're very hard to
test, and secondly, they completely ignore what's going on inside the predator's mind
when it's deciding on what animal to eat.
If a predator chooses to simply not eat anything that vaguely resembles a bee or a wasp, then
the mimic isn't under any strong selection to evolve to look exactly like the model and
there are two hypotheses out there that explain why a predator may choose to avoid anything
that might be a poor copy of the model.
The first one is known as the speed-accuracy hypothesis. When you're on the search for
food you don't want to spend ages deciding whether the food you're looking at is potentially
edible or not, if you're going to take a long time to decide if it's edible you're probably
going to adopt a safety first policy and just choose to move onto something different.
The second is categorization, which allows the placement of specific boundaries in the
items that's found in the predator's environment, and also allows them to be much more economical
with their memory. For instance, in my case, I really love insects so I know that I tend
to categorise them by order, and if you know the difference between the Dipterans, which
are the flies, and the Hymenopterans, which are the bees, the wasps and the hornets, it
can be very easy to tell them apart.
Dipterans only have a single pair of wings, whereas the Hymenopterans and basically all
other flying insects have two pairs of wings. The flies also have much fatter thoraxes,
no cinching at the waist and much larger eyes. And they're also, as the name hoverfly suggests,
much better and elegant at flying than the bees are.
However, if you're a predator without access to encyclopaedias, without a love for insects
and on top of that, you're really short on time, you're much more likely to form categories
around colours, patternings and shapes as opposed to small minutiae. And we know that
birds are able to form and distinguish between different categories such as pigeons who can
tell the difference between different species of tree leaves and also different styles of
paintings.
Now, although the specifics of mimicry psychology are still unknown, that doesn't stop it from
being a fascinating topic. I really hope you enjoyed today's episode, and as always, thank
you so much for watching me and I'll see you in the next one! Bye!
[Channel Art & Animation: Caro Waro & Cristina de Manuel]
[Music: Thastor & CryoSleepKitten] [Scripting, Hosting, Editing: Inés Dawson]
[Translated by {your name} into {language}]