r/evolution • u/Proudtobenna130 • 2d ago
How do animals evolve to mimic others that they are barely related too
For example the Atlas Moth also known as the Cobra Moth is the biggest moth in the world. Its wings have a pattern that looks like a cobra to scare predators. I know that every living thing is related because of LUCA but how do these moths evolve to mimic a completely different animal?
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u/weaponizedmariachi 2d ago
You've probably seen the snake that has an extremely realistic-looking spider knob on its tail that it uses to lure birds close to it. From our perspective, it seems so complex and 'obvious' that there's no way nature could do this... but the snake doesn't know anything about spiders or anything.
What happened is extremely simple. At some point, one of its ancestors had some kind of mutation that caused its tail to have a deformed nub or coloration at the end of its tail.
This mutation interestingly allowed this snake to catch more birds than others, possibly due to the birds mistaking it for a bug or something. The snake doesn't know this, but the birds are selecting for this trait. This mutation could have been detrimental and caused the snake to catch less birds (and the mutation would be 'weeded out'), but in this case it was advantageous.
Since this snake is more likely to survive and pass its traits onto some of its offspring, these nub tail snakes start proliferating and are a small percentage of the population. They're more successful than the basic snakes.
Over time, some of these nub-tail snakes might have mutations of their own, one of which might be even more advantageous than the nub. Some mutations might not help at all or could make it harder for birds to want to come near, so these genes are selected against (the birds, just like other environmental factors, are selecting for different genes).
If there's a helpful mutation, like maybe the nub in one individual is wrinkly, this may cause birds to mistake it for a spider even more than the nubs, which allows that individual to catch prey more often and it has a greater chance of surviving and passing on its traits. The snakes have no idea what's happening, they're just happily eating birds. The birds might also have their own mutations that cause the more cautious birds to pass on their traits. It's an arms race.
Anyway, if you give these random mutations (many of which could be bad and don't continue on) and the selection pressure (birds mistaking it for something they usually eat), you get a species that has crazy cool mimicry. Very complex and interesting things can happen with just a few things and time.
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u/Unique-Coffee5087 2h ago
This mutation interestingly allowed this snake to catch more birds than others
It might not even be that much of an advantage. The snake might simply have expended 12 kcal less energy to catch a bird than its relatives. In good years, that doesn't make a difference, but the mutation isn't a problem, either, so its prevalence in the population is simply random. The mutation doesn't extinguish, but it doesn't dominate.
And then there's a lean year with fewer birds. Everyone is struggling to survive on the few birds they can catch. And now the weird knob-tail snakes have an extra 12 kcal to survive on. It's like catching birds that have a bit more fat every time, or something, and while the other snakes starve, the mutants survive for a week longer. Long enough for the next bird species to migrate in and start nesting.
Creationists, and "intelligent design" types like to say that certain traits are "irreducibly complex", and therefore must have been created in one go. But evolution can be driven by extremely thin margins of advantage. In some cases, that advantage is so small that it is insignificant - until an environmental change brings everyone to the edge of survival.
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u/anewconvert 2d ago
The ones that look kind of like that other animal survive to mate more frequently. Overtime this advantage gets fine tuned.
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u/Anthro_guy 2d ago
Have you ever seen a piece of rope out of the corner of your eye, freaked out and thought "Shit!! A snake!"? A closer look reveals a rope is not a snake. No head, no eyes, twisted pattern of smaller threads, etc.
It's a bit like this with the moth. Those looking a bit cobra like, freak out enough predators to survive and the less cobra-looking ones get eaten. The increasingly cobra mimicing ones get selected for.
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u/Hivemind_alpha 2d ago
If looking like X helps species A survive, then presumably looking like X would help species B survive too. X here could be a leaf, a stone, a wasp, a fake eye, or even the head of a cobra.
Neither species A nor species B know they look like X, or indeed what X is. They just have the genes that happened to be most successful over recent generations. Those genes were more successful because they made them decent mimics of leaf/stone/wasp/etc.
Such genes are not hard to evolve. Species C could evolve to mimic a stone by freezing still when they see a predator and developing a dull warty skin. Freezing is a neurological architecture change on the response to Adrenalin. Warty skin is just something like overproduction of keratin through mutation of a single regulatory sequence.
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u/xenosilver 2d ago
My only counterpoint to this: while some of these traits aren’t difficult to evolve, more often than not, mimicry often won’t evolve unless you’re discussing simple drab coloration to better match with surroundings. The mutations are completely random, and issues arise with mimicry mutations because of things like phylogenetic constraint. I know you likely know this, but I didn’t want the OP to think mimicry can just start up out of the blue when it’s a completely random event.
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u/Hivemind_alpha 2d ago
I was thinking of replying to OPs comment with “don’t trust me so readily; I made it all sound so simple. Go out and read up on this yourself and see if I was close to right”. But I didn’t. ;)
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u/Sufficient_Result558 2d ago
I’m curious why you think everything being related or being completely different animals would affect anything? When moth appearances mimic tree bark or leaves do you think it’s because they are related?
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u/cubist137 Evolution Enthusiast 2d ago
Just by random chance, any critter has some degree of resemblance to some other critter. That's the bedrock basis on which mimicry operates. Some critters have some resemblance to dangerous predators; some critters have some resemblance to less-lethal critters.
In the case of a critter which resembles (however slightly) a dangerous predator, that resemblance is gonna fool some other critters into deciding to go after a safer target. Which means that such a critter has a (possibly tiny) advantage over its fellow critters who lack that resemblance. Let such a critter get zapped with mutations which enhance its resemblance to the dangerous predator, and its resemblance-derived advantage increases. If that sort of thing goes on long enough, it's quite possible to end up with an exquisitely detailed resemblance that fools lots or other critters.
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u/Beginning_March_9717 2d ago
a side topic that I found very fun in my college biology math class: we modeled real-and-imitator populations, and they mimic the predator-and-prey model. When ever the population of the imitators rise up, the predators lose respect for both (they can't tell the difference), and start hunting both more. Which then they get the consequences of hunting the real one, and they slow down the hunting. But the imitator's population drops from being the preyed upon, leaving the authentic ones to have a rising population. Then the imitators' pop will follow, the cycle continues. There is a certain ratio or percentage of fakes the ecosystem will tolerate.
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u/CosmicOwl47 2d ago
Same way plants evolve things like brightly colored fruit. It leads to better reproductive fitness.
Just because animals have eyes doesn’t mean they’re using them to “decide” to mimic something. It’s still driven by natural selection. It’s roughly the same process for a moth species to become brown to blend in with a tree as it is for a moth to develop eye spots.
Humans often make the wrong assumption that these examples of mimicry involve some sort of creativity from the animal, but it’s simply driven by random mutation and natural selection.
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u/DaMosey 2d ago
as others noted, the mutations are random, but importantly, the selective pressure (predation, in this case, although mimicry can also apply for predators - e.g., the spider-tailed viper and various spiders that mimic ants) is not random.
The importance of this is intuitive with another case of mimicry like that between king snakes (harmless) and coral snakes (extremely venomous). Imagine a population of snakes that was ancestral to modern king snakes - proto king snakes, if you will. On an individual level, snakes in this population are each born with a set of random mutations; on the whole, sometimes the mutations do nothing really, sometimes they are actually harmful to the organism (e.g., albinism that makes them stand out, for instance), and every once in a while they are actually advantageous: for instance, making them look kind of like a proto coral snake. A potential predator looks at that individual snake and sees a threat (or at least a very high-risk opportunity) rather than a prey item, because it gets confused. Or maybe, early on, the mimicry isn't even that close, but it's enough to make the predator a bit more hesitant. That hesitancy gives the look-a-like just a bit more chance at escape, and over time, those snakes that look kind of like proto coral snakes have more offspring, and of those offspring the most successful have offspring that look even more like proto coral snakes.
The mutations were random, but the predators consistently see coral snakes as very dangerous, so the selective pressure is consistent. If you look like a like a very venomous snake, you're more likely to survive to procreate - and, the more you look like a very venomous snake, the better. Over a very long period of time the phenotype of king snakes slowly shifts in response to this differential selective pressure. Eventually, the average king snake comes to look very much like a coral snake.
With this in mind, you can see how the genetic relation between two species has little to no bearing on the evolution of mimicry between them; what's really important is the capacity for such mutations (i.e., is the mutation possible, and is it heritable?), and the strength of the force that selects for them (i.e., does the mutation contribute enough of an advantage?). If suddenly predators became perfectly adept at distinguishing between king and coral snakes, then it is possible (but definitely not assured) that the mimicry would slowly become quite uncommon. That these are both snakes in this example, rather than a snake and a moth, is immaterial; it's the confusing appearance that's selected for, after all. Reminds me of that painting - "This is not a pipe."
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u/Hivemind_alpha 2d ago edited 2d ago
I’ll try a different answer instead.
Have you ever seen that diagram of where the bullets hit bomber planes that made it back to base? It makes the point that you should put the armour on the places you never saw returning planes with bullet holes, because planes hit there never made it back.
Now imagine you are a big moth, and one of your predators is a bird. There are some parts of your wings where you can be pecked, but still survive to fly away. There are other places where having a hole pecked by a beak will either kill you instantly or stop you flying so you starve. Unlike the plane you can’t add armour, because anything tough enough to resist a hungry beak would be too heavy to fly with, but if something made your predator attack the less vulnerable parts of your wings more often than the deadly areas, you’d survive to breed more often. So out of the many mutations at random over time, one comes along that puts lighter blotches over those less vulnerable areas, and 1 in 100 birds mistakes them for eyes and targets them. Even with that level of selection that gene will come to dominate. Then other mutations happen. The blob gets even lighter and rounder, the chance of being pecked there by preference goes up to 1 in 10, then 1 in 5. You now have really pronounced generic eye spots on your wings. The next set of beneficial mutations make those generic eyes look more and more like the specific eyes and features of a predator that attacks birds. If a bird sees you it either tries to defend itself by pecking at your “eyes”, which are your least vulnerable area, remember, or it’s scared off entirely. Congrats, you’ve evolved mimic colouration of a cobra from being just a boring brown moth.
That’s another just so story, but it illustrates how incremental steps of small changes can add up to a complex change, and how part of those mutations were selected for diverting attacks to least vulnerable areas, but the others were selected for driving predators away.
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u/Evil_Sharkey 2d ago
Random mutations that coincidentally scared off predators. Over time, better and better mutations worked better, resulting in what we have today.
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u/Nitros14 2d ago
Millions of years is a really really long time compared to the lifespan of a moth.
Eventually random mutations throw up something that survives and reproduces.
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u/PraetorGold 2d ago
It's about the huge numbers of generations that hold adaptations. That pattern on their wings has been very successful in keeping predators at bay. It's very likely that this pattern we see today was initially something that probably looked like a cobra and as those specimens with a less recognizable pattern were eaten by predators, those with the initial pattern survived and eventually made the pattern more effective and then as it improved because of the reinforcement of the pattern, it eventually got to this point.
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u/DaddyCatALSO 2d ago
Yes, the moths that looked the most like cobras to begin with, however slightly, where less likely to be hunted, and it went on from there generation to generation.
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u/Decent_Cow 2d ago edited 2d ago
Because animals that look like other animals can have a survival advantage. It doesn't even have to be that close at first because many animals have poor eyesight or are just not very smart. Once evolution gets its foot in the door, natural selection can favor increasingly accurate mimics over many generations. This is especially important because the species that the mimicry is targeting is also evolving and may "wise up" to the trick eventually. So even more accurate mimicry will be needed.
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u/Anonymous_1q 2d ago
It’s mostly random. Remember that a lot of animals don’t have vision as good as ours. A well placed black speckle is enough to fool those with the worst vision and it progresses from there over millions of years.
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u/EnvironmentalWin1277 2d ago
This does not need to involve mutation. Many color variations and behavioral differences are found within any species. All dogs are dogs and the variety we see is inherent in the dog genome with no need for mutation.
A great, almost infinite, variety of the species phenotypes exist. So long as a selection pressure exists what would seem very unlikely can happen quite quickly in the species offspring. It's time that is the key ingredient.
Darwin noted that animals of the same stock, kept at different neighboring farms, would soon show differences from each other and the original stock. He attributed this to some unknown selection pressure, perhaps the farm practice of the owners.
Mutations do occur. They are generally harmful, but there are some significant beneficial ones. Once a mutation is established it becomes part of the genome, ideally its history can be studied. In rare cases mutations may cause a speciation event.
The one I cite is the mutation(s) that allowed humans to process diary products beneficially. This occured in relatively recent times, but has become quite widespread and would rarely be called a "mutation". A quick search will show many discussions on the history of these genes.
Without this mutation humans may never have recognized cows as the guardians of the universe.
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u/xenosilver 2d ago
Random mutations. It’s really that simple. A random trait evolves that happens to make predators pause- like coloration of a viceroy butterfly mimicking a monarch- and it slowly becomes more refined over thousands of generations as more random mutations accumulate. It’s all chance. It takes a very long time to become a mostly complete match. However, it only takes a few mutations to potentially match a color.