I saw pictures of a praying mantis, that was supposed to look like a leaf. It was scary how accurate it resembled a green leaf. How does the DNA of a bug, know what a leaf looks like?
In: Biology
Also, look up epigenetics. More or less, it’s the ability of the environment to influence how genes are expressed. So it doesn’t always take breeding to select for more survivable traits, but environmental pressures to express desirable traits that may have been selected for at some point in the lineage of that species. Like remnant DNA.
This might not be 100% right but it’s close enough for me off the cuff laying in bed.
It doesn’t. It just happens to be that way because of evolution and random genetic mutation, just like how all of us humans look a little different from each other.
Imagine you have 100 praying mantises. 20 of them have polka dots, 20 of them are tie-dye coloured, 20 of them are just bright eye-searing neon hot pink, 20 of them have writing on their bodies that says ‘EAT ME’…and 20 of them look kind of like leaves. Not accurate leaves, but at least they’re green and vaguely leafy.
The 20 that look like leaves are going to be *far* less likely to be found and eaten by predators than the ones that don’t. So those 20 get to survive and pass on their DNA, which makes them look like leaves, to little mantis babies that will also look like leaves.
Say those 20 mantises have 100 mantis babies and they all look like leaves. 20 of them barely look like leaves, 20 look a little more like leaves, and so on until the last 20 look almost perfectly like leaves.
Which ones are more likely to survive and pass on their DNA again? The last group, right?
That’s simplified and sped up, obviously, but that’s ‘survival of the fittest’ in a nutshell. You have some mantises with DNA that happens to make them look like leaves. Over many, many generations, the praying mantises that just so happen to look like leaves are the ones that survive because of the advantage that gives them. The more you look like a leaf, the more likely you are to survive, so you end up with progressively better and better ‘camouflage’. But it’s *not* a conscious, deliberate decision to look like a leaf.
DNA doesn’t know anything. It’s purely an information storing molecule that contains information passed on from parent to offspring.
What really happens is that millions of years ago, the praying mantises that looked slightly more like leaves than the other praying mantises were more likely to successfully mate and produce offspring. Of those offspring, those that looked even more like leaves were more successful than all the rest. Slowly, over thousands of generations, the most leaf-like praying mantises were consistently able to survive and reproduce, passing on their genes and, as each generation passed, the praying mantises became more and more leaf like, until the present day.
It doesn’t. If you put that bug somewhere it wasn’t camouflaged, it’s not like it’ll change
The camouflage comes from evolutionary pressure. A species of mantis tends to live around a certain kind of flower because they attract prey.
Mantises with color or features that blend in are seen by prey less easily, so over many many generations, that colors and features get more pronounced. This is because the ones that have those features get more prey and live longer, producing more offspring which share those features.
Do this for millions of years and you get insects which have insanely convincing camouflage traits. They never tried to do it, it just happened because it helped them live longer.
The other answers all are great, but I’d like to add the concept of coevolution, wherein two species affect each other’s evolution. With the example of the insects that have slowly evolved to produce very convincing leaf-like appearances, the other side of the coin is that the eyesight of the animals that eat them, mostly birds, has also improved.
Since the birds with worse eyesight could not spot the difference between leaves and leaf-like insects, they would die out of starvation, making the birds with better eyesight survive, and create offspring with very good eyesight, and so on as bugs evolved at the same time to be more realistic and therefore even harder to distinguish.
This has created mutual evolutionary pressure which has caused the bugs to be so incredibly camouflaged; after all, if the birds didn’t keep getting better and better eyesight, then there technically wouldn’t have been a reason for the bugs to eventually become THAT hidden.
Edit: grammar
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