For example killing cockroaches makes them harder to kill or killing them with baygon makes them adapt if they’re already dead?
In: Biology
The cockroaches you killed were the ones who were poorly adapted to the environment, and therefore got killed. Other cockroaches were maybe a bit better at hiding out of your way and therefore managed to survive. And they are the ones who get to make the next generation who carry with them these adaptions. Some of these might even be better adapted to the environment and are able to hid from you even better.
The animals that survive are the ones that matter. Say you have 10 bugs and you spray them with poison and 9 of them die, but 1 survives because it has a mutation that makes it resistant to the poison. Now that 1 is the one who has offspring, and they inherit the poison resistance. Eventually all the bugs who can’t resist poison die and the ones that are left all can resist poison. The bug has now adapted to the poison.
The roaches you kill don’t evolve, but you didn’t kill them all. Some of them only got hit with a little bit of poison, and while most of those died too some of them didn’t. The ones that were slightly less sensitive to the poison are more likely to live, which lets them have babies.
Those babies, like their parents, are slightly less sensitive to that poison, so need to get hit with a little more before they die. Repeat this over many generations (where only the more poison-resistant ones survive) and you end up with a population that has evolved resistance to that poison.
They don’t. If you kill every roach that gets exposed at all, there is no adaptation.
However, if your dose is too low to kill all the roaches, the ones that survive are the ones that are more resistant, and if you spray many generations, but not to the point of actually killing all of them, they’ll get extremely resistant.
Here’s a good demonstration of this process of adaptation:
This is a pretty confusing concept, because both individuals *and* species can adapt.
This question deals with a species as a whole adapting.
When a species adapts, it happens incrementally over lots and lots of generations. Individuals help by dying. They’re like peasants in a medieval battle that get sent in to test the castle’s defences: they do a great job just by failing to survive.
Every time one individual does not die, it’s because they have something slightly different about them. A tiny characteristic that makes them a tiny bit harder to kill. That not-dead individual has a ton of babies with another not-dead individual, and the babies inherit the characteristic that lets them survive.
This is adaptability. Over time, the whole population will have that characteristic that lets them survive, because the rest of them are dead.
A great example is the *peppered moth*.
This moth used to be a lovely light grey colour to match the bark of the trees it lives in. Every now and again, one was hatched a dark grey colour and was quickly spotted and eaten by predators. With the industrial revolution, the bark of the trees were stained dark grey by soot. The light moths stood out starkly and were eaten, while the dark ones were camouflaged and survived. Now, the moths are predominately dark grey. This is adaptability.
During WW2, the Americans were interested in seeing how they could fix their planes to better survive gunfire. The planes that came back typically had been shot through the middle or the wing tips, but not mid wing. Seeing this, the Americans tried reinforcing the areas that were shot, but to no avail. they paid mathematician Abraham wald to inspect the data. He concluded that the planes that returned survived, meaning that instead of reinforcing the places that had been shot, we should instead reinforce the places that hadn’t. This is because none of the planes that came back were shot in the middle of the wing. Wald inferred that the planes that *never made it back* must have been shot in the places the surviving planes hadn’t. This is called survivorship bias, and it’s incredibly related to evolution.
The animal that dies doesn’t adapt, but the other animals that did survive live on. Their offspring have reinforced mid wings, whereas the one that died reinforced the middle and the wing tips
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