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Author Topic:   Mimicry: Please help me understand how
MartinV 
Suspended Member (Idle past 3966 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 226 of 241 (460942)
03-20-2008 3:02 PM
Reply to: Message 225 by Modulous
03-20-2008 2:33 PM



Of course. But does their similarity lead to the protection of the tasty snake in areas with noxious snakes?

I don't know if the previous observation that coral snakes are nocturnal and their mimics are diurnal has been completely refuted nowadays. If not there is a problem with their predators. But this is not the main point of refuting mimicry from my part. Preliminary we can conclude that plasteline models are attacked less during the day in the area of sympatry.


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.

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.


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.

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?

Edited by MartinV, : No reason given.


This message is a reply to:
 Message 225 by Modulous, posted 03-20-2008 2:33 PM Modulous has responded

Replies to this message:
 Message 227 by Modulous, posted 03-20-2008 3:19 PM MartinV has responded

  
Modulous
Member (Idle past 242 days)
Posts: 7789
From: Manchester, UK
Joined: 05-01-2005


Message 227 of 241 (460948)
03-20-2008 3:19 PM
Reply to: Message 226 by MartinV
03-20-2008 3:02 PM


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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 Message 226 by MartinV, posted 03-20-2008 3:02 PM MartinV has responded

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 Message 228 by MartinV, posted 03-20-2008 4:34 PM Modulous has responded

  
MartinV 
Suspended Member (Idle past 3966 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 228 of 241 (460958)
03-20-2008 4:34 PM
Reply to: Message 227 by Modulous
03-20-2008 3:19 PM



Sounds like a great idea. Do the snakes with the ventral patterns you mentioned have any mimics?

Do you mean unrelated snakes that have the same patterns? Otherwise I don't see your point. It seems to me you have agreed with Heikertinger's definition. When I challenged mimicry regarding dorsal coloration I obviously challenged also the idea that there are "mimics" of coral snakes. Mimics are connected with mimicry on my opinion and there are no mimics without mimicry.

But whatever you means by "mimic" I don't have any information of snakes looking like them.


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 Message 227 by Modulous, posted 03-20-2008 3:19 PM Modulous has responded

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Modulous
Member (Idle past 242 days)
Posts: 7789
From: Manchester, UK
Joined: 05-01-2005


Message 229 of 241 (460963)
03-20-2008 5:17 PM
Reply to: Message 228 by MartinV
03-20-2008 4:34 PM


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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MartinV 
Suspended Member (Idle past 3966 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 230 of 241 (461134)
03-22-2008 5:13 PM


As far as I know neodarwinian school offered only so-called "Mertensian mimicry" as the explanation of the mimicry of deadly poisonous coral snakes. No one bird has been observed to survive after being bitten. So how can any bird learn not to touch coral-like snakes?


During the next 80 min, the bird became progressively uncoordinated, unresponsive to my approach, and finally collapsed. By 14:05 h the bird was dead of flaccid paralysis typical of the neurotoxic effects of elapsid venom.

jstor 1989: Red-Tailed Hawk Dies with Coral Snake in Talons

Grobman who called the whole issue as pseudomimicry offered this solution:


In developing the concept of pseudomimicry, it is suggested that in secretive snakes, in which there is no selection pressure for a color pattern that is concealing, camouflaging, deflective, warning, mimicking, etc., a wide variety of non-adaptive color patterns could arise
and some might be quite bright and bizarre....
.
.
.
Among secretive snakes there is little or no selection pressure by predators for a protective color pattern. With little or no selection pressure through predation, bright colors and bizarre patterns have arisen among a variety of unrelated species of secretive snakes. Among a substantial number of those species, several independently have developed color patterns of gross similarity although differing in detail. Snakes of similar size with grossly similar patterns bear a superficial resemblance to each other. When such resembling species occupy approximately the same geographic area, the phenomenon might be called pseudomimicry. It is proposed that the superficial morphological resemblances among the coral snake, scarlet snake, and scarlet kingsnake in the southeastern United States comprise an example of pseudomimicry.

Sounds like Heikertinger who refuted natural selection as the source of mimicry entirely.

As to the so-called neodarwinian mertesian mimicry explanation - or in German "Mertensche mimikry" - Komarek from UNI Prague wrote, that the whole explanation belongs more to the realm of fairy-tales.

Mimicry, Aposematism and Related Phenomena in Animals and Plants 1998

For those who are interested in an independent view on the whole issue of mimicry and neodarwinism as well, some of Komarek's views can be found here pdf.


  
Modulous
Member (Idle past 242 days)
Posts: 7789
From: Manchester, UK
Joined: 05-01-2005


Message 231 of 241 (461183)
03-23-2008 5:24 AM


Cuckoos and their eggs
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:
...we show by experiment that host discrimination against badly matching eggs is a selective force in gens maintenance and that cuckoos lay a better mimetic egg where the host species is apparently more discriminating.

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:
Our experiments show that the key stimulus is the
cuckoo chick's rapid begging call (`si, si, si, si ...'), which sounds remarkably like a whole brood of host
chicks, and which it matched in calling rate. When single blackbird or song thrush chicks were accompa-
nied by loudspeakers that broadcast either cuckoo begging calls or calls of a brood of reed warblers, the
hosts increased their provisioning rate to that for a cuckoo chick.We suggest that the cuckoo needs vocal
trickery to stimulate adequate care to compensate for the fact that it presents a visual stimulus of just one
gape.

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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MartinV 
Suspended Member (Idle past 3966 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 232 of 241 (461905)
03-28-2008 2:36 PM
Reply to: Message 231 by Modulous
03-23-2008 5:24 AM


Re: Cuckoos and their eggs
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. I have read the theory in Flegr's Evolutionary Biology page 333 where he mentioned research of Zahavi and Soler. Sometimes it is very dangerous for host to throw away cuckoos eggs. Natural selection? As far as I know birds do not care for their offsprings after they leave the nest. Am I wrong?

quote:

Now a study in the journal Evolution offers the first evidence to support what had been considered an unlikely explanation for this behavior. Biologists studying magpies and the great spotted cuckoos that dump eggs into their nests say that the magpie hosts are not dupes at all, but have been forced into cooperation by an avian extortion scheme. But maybe I am wrong.

The researchers say the cuckoos return periodically to check on the nests in which they have left their eggs. If they find their young safely there, all is well. If their eggs are missing, tossed out by uncooperative magpie hosts, the cuckoos destroy the nest, killing the remaining egg or chick inhabitants wholesale.


http://query.nytimes.com/gst/fullpage.html?res=990CE7D81539F937A25752C1A963958260


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.

I wouldn't be so sure.

Edited by MartinV, : irony added


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 Message 231 by Modulous, posted 03-23-2008 5:24 AM Modulous has responded

Replies to this message:
 Message 233 by Modulous, posted 03-28-2008 2:55 PM MartinV has responded
 Message 234 by Percy, posted 03-28-2008 3:03 PM MartinV has responded

  
Modulous
Member (Idle past 242 days)
Posts: 7789
From: Manchester, UK
Joined: 05-01-2005


Message 233 of 241 (461909)
03-28-2008 2:55 PM
Reply to: Message 232 by MartinV
03-28-2008 2:36 PM


Re: Cuckoos and their eggs

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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 Message 235 by MartinV, posted 03-28-2008 3:37 PM Modulous has responded

  
Percy
Member
Posts: 18417
From: New Hampshire
Joined: 12-23-2000
Member Rating: 2.8


Message 234 of 241 (461911)
03-28-2008 3:03 PM
Reply to: Message 232 by MartinV
03-28-2008 2:36 PM


Re: Cuckoos and their eggs
The evolutionary explanation is that cuckoos are making it less likely that magpies with the ability to tell cuckoo eggs from their own eggs will pass their genes on to the next generation.

That doesn't rule out the "Mafia hypothesis," but it doesn't seem very likely. How would a magpie know ahead of time that cuckoos are vindictive? Plus it would be making quite a claim about avian intelligence to conclude that magpies who had had a bad experience with cuckoos in prior nesting seasons would make the connection between evicting an alien egg and having the nest attacked by a cuckoo days later, especially given the wide variety of possible predators and that attacks most often occur when the nest is unattended.

--Percy


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MartinV 
Suspended Member (Idle past 3966 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 235 of 241 (461918)
03-28-2008 3:37 PM
Reply to: Message 233 by Modulous
03-28-2008 2:55 PM


Re: Cuckoos and their eggs
We should probably define the difference between crypsis and mimicry. Do you think that some eggs are "mimicking" other eggs?
Do you consider eggs to be alive?

Edited by MartinV, : No reason given.


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 Message 233 by Modulous, posted 03-28-2008 2:55 PM Modulous has responded

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MartinV 
Suspended Member (Idle past 3966 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 236 of 241 (461921)
03-28-2008 3:54 PM
Reply to: Message 234 by Percy
03-28-2008 3:03 PM


Re: Cuckoos and their eggs
So you don't believe in Mafia hypothesis. On the other hand there could be another explanation. Neodarwinists in the case of coral snakes mimicry operate with "innate aversion" of predators towards coral snakes coloration. It cannot be learn during a predator lifespan because no one survive the venomous bite. This case can be interpretted the same way. But it sounds more like some innate "archetype" of "eggs which are mine" even though they are different in shape and coloration. Those species can really experience some "survival advantage". But this mysterious process of "innate aversion or acceptance" goes ahead of natural selection. There is some animal premonition involved I would say.
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Modulous
Member (Idle past 242 days)
Posts: 7789
From: Manchester, UK
Joined: 05-01-2005


Message 237 of 241 (461923)
03-28-2008 4:12 PM
Reply to: Message 235 by MartinV
03-28-2008 3:37 PM


Re: Cuckoos and their eggs
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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MartinV 
Suspended Member (Idle past 3966 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 238 of 241 (462526)
04-04-2008 2:48 PM


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):

Heikertinger ridiculed "natural selection" as the source of aposematism, mimicry and related phenomena. It occurs too often to be explained by "natural selection". Ladybirds are very conspicuous regarding their coloration. Yet neodarwinian school doesn't have any plausible explanation of it. The same for bugs. Who can exactly tell apart conspicuos coloration - as mimicry or aposematism - of wasps, coral snakes, butterflies, fruiting bodies of mushrooms, bugs, ladybirds and insist on "natural selection" as the only explanation of it? Even the great Darwin solved the problem by these words:
"I could not answer, but should maintain my ground ."

1

2

3
4

5

hehe.

Edited by MartinV, : No reason given.


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Modulous
Member (Idle past 242 days)
Posts: 7789
From: Manchester, UK
Joined: 05-01-2005


Message 239 of 241 (462534)
04-04-2008 4:46 PM
Reply to: Message 238 by MartinV
04-04-2008 2:48 PM


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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MartinV 
Suspended Member (Idle past 3966 days)
Posts: 502
From: Slovakia, Bratislava
Joined: 08-28-2006


Message 240 of 241 (462941)
04-10-2008 3:57 PM


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. Black-yellow patterns are so common patterns in insect realm that it is hard to imagine why only some dragonflies should mimic wasps where other conspicuous dragonflies thrive as well in their "struggle for life". 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".

but what about this one:

or this one


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