Clever crows, but a real shame other predators are being killed off because of their unfamiliarity with an invasive species. I wonder if any naturally immune individuals will rise up from the loss of their main populations.
More likely some of those predators will learn to avoid them rather than become immune to their poison. Hopefully they will learn that before they are reduced to unsustainable levels.
Do most animals have that ability though? How do you learn from something when you're dead from it nearly instantly? I don't think snakes have knowledge outside of instinct. That's the point of this crow article.
Not in one individual, but animals that die from eating them will self select themselves out of the gene pool (if done before they get a chance to mate), over time only leaving those that avoid it. The more generations that survive this the more it becomes an instinct.
Article contains a link to a story about how conservationists are trying to 'teach' quolls (Australian native marsupial) by negative association with toad-meat sausages laced with a nausea inducing compoound : http://www.australiangeographic.com.au/topics/wildlife/2017/...
Natural variation and selection. (Biological) Evolution changes populations, not individuals.
Suppose there's one snake that is genetically disposed not to eat toad-shaped things, frogs, cane toads, anything like that, the same way I don't like nuts. They're not toxic to me, I could eat them, but I don't. Previously toads weren't toxic to snakes, but that snake didn't eat them.
Normally that snake has a small disadvantage, other snakes eat toads and it goes without. Too bad. But now it won't get poisoned. This means it's slightly more likely to survive to adulthood, breed and produce more snakes.
Further genetic changes to avoid toads will also be selected for in the same fashion.
This process is very slow in multi-cellular creatures, but it does exist. It may not be fast enough to adapt to the cane toad of course.
Appreciate your comment. It always impresses me how many people misunderstand the (what I feel to be) basic concepts of evolution. I'm not educated on the matter either, mind you - I'm sure I'm very ignorant on many aspects of it.
Regardless, it always makes me wonder how much the anti-evolution "movement" would be affected if people simply had a better grasp of it.
Quite a bit of the provided possible outcome rests on likelihood of certain genetic factors and, relative size of snake population, and how quickly cane toads spread.
The actual values of these variables (and a few more I'm sure) can change whether one population dies out or not and how quickly. Just because evolution provides a solution to the general problem, doesn't mean there's a solution that saves the population when the specific problem is looked at in detail. Invasive species cause local extinctions all the time.
We're not talking about natural selection, we're talking about actual learning(crow article), and discussing if other animals have that ability. I understand how evolution works.
I don't think so, the commenter was saying that a snake that avoided toads by way of its genetics, would be more fit, and thus reproduce more snakes that avoid toads. Genetics can affect instincts so this is not far fetched. But yes, learning genes would be much more apt and effective over a larger obstacle course. It is tough to see how a snake is going to develop a neocortex though.
I know sentience is an abused word, but for almost any of its practical definitions that's a false statement.
Sentience is the ability for subjective experience, which applies to any of the animals being discussed here. If you're thinking of something like self-awareness (a totally separate quality), you're probably correct. But that has nothing to do with the ability to learn.
Those actions can still be done unintentionally. For example, a particular kind of snake can prefer to eat some particular kind of fruit when they are young, which also happens to be the favourite plant for a cane toad to rub on to get rid of itchy bottoms.
Pretty cool link on the Colorado River toad. Apparently raccoons use the same strategy as these crows, turning the toad over on its back and eating the belly.
