Take caterpillars for example: if a bird eats a fatally poisonous caterpillar and dies immediately, it learned nothing, the caterpillar gained nothing for being poisonous, and that caterpillar species will continue to be preyed upon.
But if a caterpillar is only mildly toxic, and a bird eats it, the bird may survive and learn to avoid things that look like it, and that caterpillar species as a whole benefits as the cycle continues.
Am I missing something obvious? Wouldn’t it make more sense for mild toxicity to prevail as the more advantageous trait, over time?
edit: another point of confusion — more toxic animals tend to advertise their unsavoriness with bright colors. We generally accept that predators know to avoid brightly colored prey, but if they die during their very first encounter with one, how is that info passed along to other predators?
In: Biology
Predators that can spot whether or not it is poisonous will have a better chance of survival as a group, basically selecting them until no one except defectives try eating them.
That’s why some poisonous animals have very bright and distinctive colours, to warn predators and make it easier to recognise them as poisonous
Fun fact : some animals fake being poisonous by having these bright colours
Less predators = less chance to die, you take one for the team, but remember, that predator can multiply and make more predators. 1 is less than 5, which themselves could multiply.
> if they die during their very first encounter with one, how is that info passed along to other predators?
The predators are evolving too. Some birds like green caterpillars and some like red ones. The green ones taste bad, the red ones are lethally toxic.
When the bird population goes eating caterpillars most of the birds that prefer the red caterpillars simply die and don’t reproduce. The next generation of birds trends towards not liking red caterpillars.
No information is conveyed, the population just gets sorted by natural selection. As the caterpillars evolved toxicity their predators were evolving at the same time, acquiring an aversion to the toxic prey… or even a resistance. By the time another predator enters the environment a red caterpillar that gives their adapted bird a tummy ache will instead kill the new predator right away.
Evolution doesnt work by “learning”. It works by snuffing things out. If a specie of bird eats toxic caterpillar, they will die out. And what you have left are birds who live by not eating toxic caterpillar, and toxic caterpillar who live by not being eaten by the birds.
Same with bright colors. We can imagine this to be a strategy, but there is nothing conscious about it, just evolutionary pressures.
If they are extremely toxic and the trait remains it means that is advantageous for their survival.
Variation in the initial predator population means some will try to eat the poisonous prey and some won’t. The ones that do will die. Now you are left with a population less likely to try to eat poisonous prey.
You might wonder how the poison evolves since the prey gets eaten and can’t reproduce. For that, you must understand genetics the way Dawkins lays out in The Selfish Gene. We tend to learn in school that organisms reproduce, so everything is about organisms and organisms just *have* genes.
That is not the right perspective. It is the gene that reproduces. A gene for being poisonous will randomly turn up through mutation. Initially it will have no effect on survivability, so it will obey genetic drift: it will randomly be snuffed out by chance, or wind up spread through the population. When the latter happens, it is finally widespread enough to cause selective pressure through what was discussed above. So now you have predators that avoid these poisonous prey, because the poison was a selective pressure on *them*. This means the poisonous prey are not preyed on as much, which means having the poison is now a selective pressure on *themselves*, so it is a selected trait and will become increasingly common in the population.
Actual learning from experience is entirely unnecessary.
In general you have to remember a single bird/bug/whatever does not matter (of course there are exceptions like pandas because of a slew of breeding problems)
You are looking at it as if both do matter, but it is the group that does. Animals may not be super intelligent but they aren’t so dumb as to avoid learning. That bird over there ate it and died, now I’m not going to eat it. And if enough of us living birds decide not to eat it eventually very few will be eaten.
The mildly poisonous approach ends up as nothing but a generational arms race as the bug gets stronger poisons to counter the built up immunity until eventually the bird becomes completely immune to the poison and now it is open season forever
Latest Answers