Mimicry: Please help me understand how

Agreed. The evolution of aposematism is not the topic, but mimicry is. All that needs to happen, for whatever reason, is that predators learn to avoid noxious models and we have the potential for mimicry. There are other driving factors to mimicry which we haven't touched on, and we'll skip by them for now.If predators avoid non-noxious mimics after having eaten a noxious model more than they would have had they not eaten a noxious model, then we have a selective pressure towards mimicry. Studies explicitly designed to test this hypothesis have been carried out in the field and in naturalistic lab conditions. They show that birds do come to recognize noxious models and that they also mistake mimics for them and if there is choice towards something tastier, they tend to avoid them.This has been carried out with things other than birds - such as toads with similar results. If an insect can fool a predator just one in ten thousand times into not eating it because it looks like something that the predator would rather not eat right now - we have selective pressure.

Why? What difference does aposematicism make to the argument? If honeybees have no aposematic colouration, they share this fact with many species. Why single out honeybees? Sometimes, in a fitness landscape, there are some chasms that cannot be leapt without taking a significant drop in fitness. Natural selection isn't about perfection, just 'good enough'. You could drop mimicry all together and simply say "If having stings or tasting noxious is a good defence mechanism, why don't all insects have this defence mechanism?"

Yes. The topic isn't about the evolution of aposematicism. Care to get back to mimicry? Whether or not honeybees are aposematic is irrelevant - things mimic them, and predators confuse the two is the relevant discussion here.

All I need to show is that after eating noxious tasting insects, there is a tendency in predators to avoid things that look like noxious tasting insects. It doesn't matter why an insect looks noxious, only that a predator is able to discriminate a noxious insect from a non-noxious one - fooled only by non-noxious mimics of course. That question doesn't even make sense. Either way it doesn't matter. As long as predators can identify a noxious insect in the future after having eaten one in the past - regardless of how that discrimination takes place, we can be assured that there is a possibility that mimicry may occur in non-noxious insects. Where mimicry does occur, it should be some characteristic that the birds use to discriminate between noxious and non-noxious insects. That might be a certain colouration or it might be a smell or a flight pattern. You chose to focus on colouration, but now you are trying to steer the topic into realms of suggesting that birds don't discriminate in terms of colouration - yet evidence exists that they do.You have simply dismissed this evidence.And that's basically where we stand.The evolution of these characteristics in models is not important, the evolution of these characteristics in mimics is.

If they aren't mimics, they aren't the topic. However, read the next two sentences where it says that they are mimics according to pigeons.

My apologies. I made the assumption that we were talking about predominantly insect predators. There will still be enough bee-eaters for what? If there are less predators that eat wasps than eat flies, there is a potential advantage for a fly population to look a little like a wasp and thus have its members eaten less. Don't be silly. When noxious insects are the only insects, insectivores have no choice but to eat nasty meals and as we established earlier, they will do so. When did Darwin make this prediction? It seems contrary to common sense since it assumes no other selective pressures. Then why focus on noxious/aposematic insect species? Why not focus on Gazelles who run fast to escape from predators. According to you they should dominate the world by now - they have a small advantage. Also - EVERY species on the planet has some adaptation that gives them a small survival or reproductive advantage and thus EVERY single species on earth (according to your strange logic) should populate the world.I estimate that there can form a balanced ratio of predator-prey where the predators catch enough prey to make a living, and enough prey survive to populate the next generation. That any given population will have an approximately maximum size in any given environment. You seem to have a weird understanding of biology to think survival advantages should continue increasing population size ad infinitum. Survival/reproductive advantages can increase maximum population size but they are more famed for changing the frequency of themselves within a population.

No it isn't. Evolutionary theory is used to describe how biodiversity occurred it doesn't predict that diversity has to decrease. A simple thought-example. A hypothetical organism requires 1KJ of energy to grow to reproductive size. It lives in an area that has 1MJ of exploitable energy. It is impossible in this scenario for a population size of 10,000 to all reach reproductive size. Only the ones that are best apt at staying alive long enough to exploit the limited energy will prosper. Thus the specimens that are best at efficiently harvesting energy and avoiding death will be more represented in the next generation when their children will be trying to exploit the exploitable energy supplies. Indeed - as the population of noxious insects increases in size, the chances that predators will exploit the food source will increase - thus reducing the population size and keeping the population size in check. There is an maximum optimum population size where the aposematicism is effective, going above that size will result in the population being reduced down to below that maximum optimum. No doubt you have heard of the careful balance of nature. This is something that can and does switch and change within our lifetimes...it cannot be the explanation for the evolution of imperfect mimicry. Yet they have less predators than things that look less waspish so the simplest explanation is also the wrong one.

Only if the only selection pressure was on looking more waspish. Since this is never the case, we don't anticipate that perfect waspish insects will have to evolve. It's called natural selection. Let's say that in order to look more like a wasp, the insect has to compromise flight skill. There will be a balance between looking waspish and being skilled and the optimum solution will eventually be found - no doubt some kind of compromise between the two.

No, they don't have to be more skilful than wasps. No - its a paper on defensive behaviour, why would I expect to find a discussion on selection pressures on morphology?

Yes, warning colouration only goes so far, but if they can't fly - wasps die. There are many things a wasp must have in full working order to expect to survive long enough to have those fully working genes passed on. Agreed, which is why wasp mimics aren't amorphous blobs of yellow and black biomasses.

That was one heck of a subject change Martin. This is not a thread on warning colouration but on mimicry. IF the colouration of the horntails is aposematic then the pressure to keep it should be obvious. If it is not, then there is presumably some other reason for its colouration. This isn't really the topic though - so why bring it up?

The colouration of some insects may well play no role in their protection. Potential examples of this are not relevant to the topic though. Then let's look at those wasps that are proposed to have colouration that serves as a warning, and not at those that don't. It might be mimicry or it might not, but it is not relevant to whether or not the colouration of noxious wasps is aposematic. It doesn't matter what the explanation of it is for this topic unless it is proposed to deter predators - in which case it might be mimicry which would make it on topic.

The topic is about mimicry. If you aren't talking about mimicry you aren't on topic - how is that not clear? It isn't anything to do with me determining anything. There are lots of non-noxious wasps for a start.There is no requirement for warning colouration to evolve in insects that are noxious, as I have answered on a number of occasions. They are irrelevant to this topic unless you want to discuss mimicry of these insects...for instance we could talk about ants that mimic other species of ant and invade their nests. That is mimicry and there is no warning colouration there.

Sounds like an interesting direction to take the thread. Do you have anything more on them than a couple of jpgs?

That wasn't Darwin 'solving' the problem, it was Darwin stating that he was unable to solve the problem and asking for some input. The response from Wallace was essentially 'aposematism':

quote:

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I had then just been preparing for publication (in the _Westminster Review_) my rather elaborate paper on 'Mimicry and Protective Colouring,'

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The letter itself is lost, but clearly Wallace was the best person to ask this of given he had just completed a paper on it.and Darwin replied:

quote:

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My dear Wallace,--Bates was quite right, you are the man to apply to in
a difficulty. I never heard anything more ingenious than your
suggestion, and I hope you may be able to prove it true. That is a
splendid fact about the white moths; it warms one's very blood to see a
theory thus almost proved to be true.[57] With respect to the beauty of
male butterflies, I must as yet think that it is due to sexual
selection

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So, he was confident that selection would provide the answer, he asked an expert in the relevant field and received an answer. That is very telling - it tells me that Darwin was both modest and smart. I can not only imagine a physicist saying something like 'I don't know the exact answer, but I am confident that the theory is capable of explaining it - you have studied this field more than me...what do you think?', but I've seen it actually happen.Likewise with mathematicians, only in a different way.