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Junior Member (Idle past 6128 days) Posts: 2 From: Alabama, USA Joined: |
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Author | Topic: Mimicry: Please help me understand how | |||||||||||||||||||
Modulous Member Posts: 7801 From: Manchester, UK Joined: |
Did you have a point?
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
I think I missed a chapter in your explanation. A man doesn't know the answer to a question about caterpillars so he asks a friend who refers him to a third man who gives what he thinks is the answer to the question and the first man tells the second man. The idea aligns with a hypothesis the second man had developed regarding butterflies. Therefore they suffered from the medical condition of sclerosis?
Do you see how I might think there is something missing from what you have written regarding your reasoning?
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
Your rendering of the story is nice and almost correct. I like it, just a small improvement: A man doesn't know the answer to a question about conspicuous coloration of insects so he asks a friend who refers him to a third man who gives what he thinks is the answer to the question and the first man tells the second man. The idea aligns with a hypothesis the second man had developed regarding conspicuous coloration of insects. Perfect. Well, I don't see that there is much difference only you have specified colouration and generalized 'insects' instead of caterpillars/butterflies. That's fine, but you clipped the end off about how this is diagnostic of a medical condition which was apparently your point and you once again neglected to give further details about how you arrived at this conclusion as I requested. So, with a little bit more explanation...could you tell me what your point is?
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
For those wasps having more warning coloration would have given them some advantage, wouldn't it? Predators would better remember more conspicuos wasps and their alleles should spread over populations more readily. Maybe it would, maybe it wouldn't - I suppose we could test that hypothesis. Either way, what is your point? If it would serve as an advantage, and it is possible to get to it without taking a reduction of overall fitness - then we might see it if it were to occur. If an appropriate mutation doesn't occur, or if getting there requires some kind of temporary sacrifice of fitness - we probably won't see it happening. We could point to a thousand examples of poor design - not just wasps that don't advertise their own noxiousness, we can start with the human body. However, stupid design and the reasons why we see so much of it are not the topic. We're meant to be talking about mimicry. I've said it over and over again. Aposematicism isn't inevitable - evolution doesn't predict that all noxious animals must develop it, it is an event that can be explained if it does occur.
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
Nice 30 year old article. I wonder how you might explain
quote: this strange pattern. Read more here. Sounds like a little more than pseudomimicry to me.
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
I'm not following you.
How do you explain the pattern of attacks without reference to mimicry?
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
There must have been a difference between attacks on real snakes in reality and their plasteline models in experiments. Still not following Martin - how would that explain the correlation between birds attacking plasticine mimics of noxious species and frequency of noxious species in that environment? You've told me what evidence you believe exists, what's your hypothesis that would explain the correlation detected in this study?
And how do you explain the aposematic coloration only on ventral side of some snake species? The topic is mimicry, not aposematicism. Feel free to start a new topic.
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
Authors picked up two sympatric "mimics" - scarlet kingsnakes and sonoran mountain kingsnakes. Such selection is no way representative sample to explain the whole phenomenon of coral snakes mimicry. Of course. But does their similarity lead to the protection of the tasty snake in areas with noxious snakes?
Even if the experiment with plasteline models could have some relation to reality it doesn't address to main point: Was it really natural selection that led to such resemblance? Maybe, maybe not. There is certainly a selective advantage for some of these snakes to keep looking the way they do, that's for sure. If the two species are closely related, they may have merely inherited their striking appearance, and the fact that one is noxious allows the other to not be noxious but still be afforded some protection.
We are discussing coral snakes mimicry. This example is related closely with it. It's called topic drift. The OP was talking about mimicry of insects to their background or inert things...camouflage essentially, we drifted to discussing bees and wasps and their mimics, then you moved us over to snake mimicry and snake aposematicism. The function of a certain species' appearance is not really of interest to me in this topic, not unless it has a mimic.
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
Heikertinger defined resemblance as mimicry only if selection have led to the resemblance. In case selection was not the force behind it, it is pure coincidence of coloration that might give some survival advantage or not - but it is not real mimicry. So I don't know what is your definition of mimicry. There might probably be some survival advantage of looking like noxious species now. Sounds like a decent enough definition for mimicry.
The topic of the thread is mimicry. Mimicry of wasps and mimicry of coral snakes are famous examples. So why don't discuss them in this thread? Sounds like a great idea. Do the snakes with the ventral patterns you mentioned have any mimics?
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
Do you mean unrelated snakes that have the same patterns? Yes, something like that, presumably living in the same area.
But whatever you means by "mimic" I don't have any information of snakes looking like them. So they aren't really a good example for a topic about mimicry then. Shall we stick to discussing cases of actual hypothesized mimicry?
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
Cuckoo eggs are interesting. The female bird lays the eggs in a nest of her choice and she is very likely to choose a nest of the kind of bird her mother chose. Nest choice seems to be determined by the female chromosome (W). This isn't just a species specific thing, there are different races (or gentes) within a species that parasatize different nests.
It seems that egg mimicry is present when cuckoos parasatize discriminating hosts.
quote: Here's a hypothesis, if this is natural selection at work - and not just the way things happen to be - then we should probably find that species that have had a cuckoo problem will be more likely to be discriminative than species which probably haven't (wrong diet, location, size or accessibility of nest etc). The result? Chaffinches, song thrushes and blackbirds - suitable hosts for cuckoos are fairly good at discrimination. The flycatcher is another suitable host, but with a twist: spotted flycatchers have an accessible nest whereas pied flycatchers nests can often only be entered by a small bird and the female cuckoo is often thus excluded. As us evolutionists expect, the spotted flycatchers tended to reject fake cuckoo egs and pied flycatchers happily accepted them (they've not developed any discriminative cuckoo defence mechanism because their nesting habits are already doing this work). Just to drive the point home, cuckoo chicks manage to mimic the begging calls of their host chicks, but it is more fascinating than that: a single cuckoo chick actually mimics a brood of chicks of the host species.
quote: Given the variety of hosts that are utilized by the same species, the mimicry of eggs that takes place, the ability of some bird species to engage some discrimination and the correlation between discrimination and mimicry along with mimicry of begging calls surely cannot be simply dismissed in the fashion MartinV would like to. What other situation could have actually lead to this state of affairs if not selective pressures acting in an ages long arms race between various birds?
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
I don't know if the situation regarding the discrimination of cuckoos eggs is as simple as presented. There is a theory that other birds could tell apart their own eggs and those of cuckoos. Yes, I presented evidence that some other birds can tell cuckoo eggs apart from their own. I presented evidence some birds can't. I even posted evidence that birds which could never have been parasitized by cuckoos are amongst those which are worse at this discrimination than those which might have, or are being currently parasatized by cuckoos. The exerpt you posted is just another strategy besides mimicry. In this case, birds that are discriminative have their offspring killed so discrimination is punished more harshly than non-discrimination. The cuckoos have discovered a strategy that can prevent their hosts from evolving an effective method for foiling the parasite. As the article you linked to points out - this behaviour is not universal amongst cuckoos and their hosts. Nevertheless, we still have the mimicry issue to sort out. One species lays a variety of different looking eggs. The differences seem related to the appearance of the eggs of the host species and any individual female bird will always lay eggs of the same appearance in the same host species (with about 10% error rate). How do you explain this?
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
Is it your position that crypsis can evolve, but mimcry cannot?
Yes, cuckoo eggs are commonly referred to as mimicking their host eggs. Eggshells, to my knowledge are not living - but they produced as a result of the phenotype of cuckoos.
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
My latest post at AtBC and RichardDawkins.net (and I hope it is not my last post here - Modulous is also neodarwinian admin here you know) I wouldn't dream of suspending you Martin for infractions in this thread Martin, I am an active opponent of yours and I consider it bad form to do so. However, I do note that you have a tendency to repeat your position (or rather someone else's position that you agree with) over and over again. If you want to discuss ladybird mimics, then name a species you think is meant to be a mimic, the name of the supposed model and we'll talk. I also note that you are saying exactly the same kinds of things at RichardDawkins.net as you said here months and months ago as if you had learned nothing since then. For example: in the case of wasps we have established here that birds don't avoid wasps because of their stings but because of learning they have a noxious taste. I have to wonder if you have learned anything from this interaction at all? If not, why are you bothering? I've learned an awful lot after reading lots of papers about the subject. Or we could continue to talk about cuckoo eggs, they seem interesting. Edited by Modulous, : No reason given.
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Modulous Member Posts: 7801 From: Manchester, UK Joined: |
The main question persists. Discussing "mimicry" requires that "mimicry" exists. But neodarwinists do not have any clue - except their fantasy of course - how to tell apart aposematism, mimicry and a pure coincidence of similar color patterns. No Martin, you are trying desperately to pick difficult cases and present them in an informal setting and you exploit "I'm not sure on that but..." answers to support your thesis that there are no clues. If you want, we can continue talking about cuckoo eggs or maybe ant mimics.
I would say we have a pallete of coloration in dragonflies and coincidentally some of them look waspish. The same for many other species or families. Only a prejudiced mind of a selectionist see in all those cases "mimicry". Well, I've said it many times - there are possibly cases out there where appearances to other species are either coincidence or because of relatedness. However, the waspish look of dragonflies might, in some cases, provide a slight selective advantage penalizing any members of the population that look slightly less waspish helping maintain the pattern. Still - I'm happy to talk about less ambiguous cases, but you seem to change the subject when I bring them up - so it makes debate difficult.
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