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Author Topic:   Foul Tasting Bugs
RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 16 of 47 (550628)
03-16-2010 8:11 PM
Reply to: Message 14 by InGodITrust
03-16-2010 4:12 AM


evolution is in populations not in individuals
hi again InGodITrust,
Like with many other aspect of evolution, this gets so complicated it is mind-boggling (for me anyway).
One thing to remember is that evolution occurs in populations, not in individuals.
Evolution is the change in frequency of hereditary traits in breeding populations from generation to generation in response to ecological opportunities.
Once bad taste spreads in a population, then selection can operate on that population compared to other populations of bugs without the noxious taste, thus giving the population with some noxious tasting bugs an advantage, allowing the noxious taste to spread further within the population.
Initially such a mutation would be neutral to selection pressure, and thus subject to neutral drift and stochastic processes.
Enjoy.

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


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This message is a reply to:
 Message 14 by InGodITrust, posted 03-16-2010 4:12 AM InGodITrust has replied

Replies to this message:
 Message 18 by InGodITrust, posted 03-17-2010 5:09 AM RAZD has replied

  
Taz
Member (Idle past 3291 days)
Posts: 5069
From: Zerus
Joined: 07-18-2006


Message 17 of 47 (550638)
03-16-2010 9:10 PM
Reply to: Message 14 by InGodITrust
03-16-2010 4:12 AM


Re: Sounds rather obvious to me
InGodITrust writes:
Thanks everyone. I'm still thinking this through. Like with many other aspect of evolution, this gets so complicated it is mind-boggling (for me anyway).
This is exactly the reason why I encourage people to learn the basics first before they try to tackle bigger things. This is like trying to solve calculus problems even though you haven't even learned basic algebra yet.
First of all, you need to learn the most basic fact about evolution, which is that individuals don't evolve. The smallest unit that can evolve is a population. A mutation for foul taste in an individual would start out neutral. Over time, the trait is passed onto other individuals through random breeding. Over time, the foul taste in parts of the population gives the entire population an advantage over other populations because predators remember what bugs with foul tastes look like. Over even longer periods of time, this specific trait is spread throughout the population because it gives the foul tasting bugs an advantage.
But again, you need to learn the most basic things about evolution. I highly recommend reading some books written by honest to god scientists and not just creationist propaganda. Better yet, wait until you learn it in school.

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InGodITrust
Member (Idle past 1669 days)
Posts: 53
From: Reno, Nevada, USA
Joined: 05-02-2009


Message 18 of 47 (550661)
03-17-2010 5:09 AM
Reply to: Message 16 by RAZD
03-16-2010 8:11 PM


Re: evolution is in populations not in individuals
Mr. Jack, Wounded King and others have responded--without reservation--that kin selection is responsible for the foul taste. So I gather that this is a widely accepted explanation. And kin selection is a form of natural selection.
I understand how kin selection works once the foul taste is established throughout a population, but it is harder to see how the foul-taste blood line gets started and spreads through a population by natural selection.
To simplify the matter, I first thought of a population of bugs that tasted okay. Then one individual bug in that population turns up with a genetic mutation that gave it all-out horrible taste, that a predator would reject. This is unrealistic, because the development of the foul taste would probably come in increments, rather that all at once.
At any rate, how does natural selection spread this gene from the first individual possesing it to the rest of the population? Might the gene come with a cost, and hamper the first individual in some way? Would it be able to attract a mate as easily?
But RAZD, you have the answer with the "neutral mutation." Neutral mutations can be used to fill in a lot of blanks, I would guess-- kind of a get-out-of-jail-free card. It doesn't seem to me that the spread of neutral mutations, in this case, can be considered natural selection. It is chance.
If the foul taste came about de novo incrementally, or if it existed for another purpose but was later refined for defense, it still seems that if neutral mutations were involved, the taste would be a result of chance more than natural selection.

This message is a reply to:
 Message 16 by RAZD, posted 03-16-2010 8:11 PM RAZD has replied

Replies to this message:
 Message 20 by Wounded King, posted 03-17-2010 5:23 AM InGodITrust has not replied
 Message 21 by Dr Jack, posted 03-17-2010 5:50 AM InGodITrust has replied
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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 19 of 47 (550662)
03-17-2010 5:11 AM
Reply to: Message 15 by RAZD
03-16-2010 8:05 PM


Re: kin selection or just evolution in sub-populations?
I'm not sure what you think is the difference between your answer and ours, you have just swapped 'sub-population' in to represent the population of more closely related organisms, but the chances are that the sub-populations where these traits are prevalent will be more closely related individuals since we know that many of them at least share the trait for unpalatability and individuals within the same area are also normally more likely to be related.
The isssue is why does a trait prevail when it doesn't directly benefit the individual exhibiting that trait, the answer is kin selection. If you want to claim that none of the individuals exhibiting the same trait in the sub-population are related, or that they are generally no more related than with individuals of another sub population, then I think you will have a hard row to hoe.
So I think you are making a distinction without a difference.
TTFN,
WK

This message is a reply to:
 Message 15 by RAZD, posted 03-16-2010 8:05 PM RAZD has replied

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Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 20 of 47 (550663)
03-17-2010 5:23 AM
Reply to: Message 18 by InGodITrust
03-17-2010 5:09 AM


Genetic Drift
quote:
But RAZD, you have the answer with the "neutral mutation." Neutral mutations can be used to fill in a lot of blanks, I would guess-- kind of a get-out-of-jail-free card. It doesn't seem to me that the spread of neutral mutations, in this case, can be considered natural selection. It is chance.
Actually RAZD's answer about the spread isn't really 'Neutral mutation' but rather 'Genetic Drift', which is indeed essentially the effect of chance on the spread of a mutation.
Regardless of the fitness benefit or cost of a mutation stochastic processes will tend to change the frequency of the resulting allele in subsequent generations of a population. In some cases this will lead to even a strongly beneficial mutation being lost or deleterious mutations becoming fixed in a population, but it can also increase the rate at which a beneficial mutation runs to fixation.
It may be that what we see with noxiousness is also a frequency dependent effect where the mutation only becomes beneficial when it is widespread enough in the population to confer protective benefit. In this case clearly drift is required to raise the allele frequency to the necessary level initially.
TTFN,
WK

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Dr Jack
Member
Posts: 3514
From: Immigrant in the land of Deutsch
Joined: 07-14-2003
Member Rating: 8.7


Message 21 of 47 (550665)
03-17-2010 5:50 AM
Reply to: Message 18 by InGodITrust
03-17-2010 5:09 AM


Re: evolution is in populations not in individuals
I understand how kin selection works once the foul taste is established throughout a population, but it is harder to see how the foul-taste blood line gets started and spreads through a population by natural selection.
RAZD claims neutral drift; I make a different claim. Exaptation: foul tasting chemicals emerged not because they were foul tasting but because they performed some other function in the organism and just happened to also be foul tasting.

This message is a reply to:
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Replies to this message:
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dwise1
Member
Posts: 5930
Joined: 05-02-2006
Member Rating: 5.8


Message 22 of 47 (550697)
03-17-2010 11:25 AM
Reply to: Message 21 by Dr Jack
03-17-2010 5:50 AM


Re: evolution is in populations not in individuals
RAZD claims neutral drift; I make a different claim. Exaptation: foul tasting chemicals emerged not because they were foul tasting but because they performed some other function in the organism and just happened to also be foul tasting.
Agreed. While new traits can arise and establish themselves via neutral drift, it is also very often the case that an existing trait take on a new function.
From "The Bombardier Beetle Myth Exploded" by Christopher Gregory Weber, Creation Evolution Journal 1:3, Winter 1981, pp 1-5 (reprinted at The Bombardier Beetle Myth Exploded | National Center for Science Education):
quote:
As Thomas Eisner shows in his article "Chemical Defense Against Predation in Arthropods" (Chemical Ecology, 1970, pp. 157-215), hydrogen peroxide is a normal metabolic byproduct in insects, and various quinones are used to harden (or "sclerotinize") the cuticle of insects. All kinds of insects therefore secrete these chemicals. As a byproduct, hydroquinone tastes bad to predators and is the chemical that makes stink bugs stink. So, if an insect's cuticle became indented, forming little sacs to store some of this hydroquinone, it would have an advantage over its fellows even if its storage mechanism was not yet very efficient.
Schildknecht himself points out that the carabid family of beetles has little sacs like this. They have glands that exude enzymes into pygidial bladders that empty into the anus, even though these don't explode. So, even though the bombardier beetle is the only carabid beetle to shoot boiling liquid at its enemies, the other carabid beetles, living in different ecological niches, survive very well because, with their thick-walled little sacs, they can poison their enemies but not themselves.

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RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 23 of 47 (550704)
03-17-2010 12:52 PM
Reply to: Message 18 by InGodITrust
03-17-2010 5:09 AM


Re: evolution is in populations not in individuals
Hi again InGodITrust,
Mr. Jack, Wounded King and others have responded--without reservation--that kin selection is responsible ...
I find the concept of bugs having an awareness of kin to be somewhat problematical, and to me kin selection only works when one is aware of kinship at some level.
And kin selection is a form of natural selection.
Correct, the action of the one benefits the survival or reproduction of their kin.
But RAZD, you have the answer with the "neutral mutation." Neutral mutations can be used to fill in a lot of blanks, I would guess-- kind of a get-out-of-jail-free card. It doesn't seem to me that the spread of neutral mutations, in this case, can be considered natural selection. It is chance.
There are often disagreements when information is incomplete and conclusions are tentative - as is the case with much of science. Don't ask for absolute answers, as they are not the purview of science, rather they are the purview of people who think they know absolute truth/s.
Yes it is chance, a stochastic effect, that any mutation happens. One thing to keep in mind is that not all mutations are subject to selection when they occur. They can become beneficial or detrimental at a later date, either in conjunction with a later mutation or a change in the ecological opportunities. In one experiment it was determined that a neutral mutation enabled a later mutation to be beneficial.
Most mutations are neutral - they don't affect the selection of the phenotype either by reproduction or by survival - but they do add to the variety of the population to enable it to be more flexible in later responses to ecological changes.
If the foul taste came about de novo incrementally, or if it existed for another purpose but was later refined for defense, it still seems that if neutral mutations were involved, the taste would be a result of chance more than natural selection.
Natural selection has nothing to do with the appearance of the foul taste, or any other mutation, just with the effect on survival or breeding afterward, it is a response mechanism.
The taste would be due to the chemical makeup of various proteins, and could be due to a combination of several proteins, as what is being tasted is the "recipe" of the bug, not the individual molecules. So yes, it could build up over time in several layers of mutations.
To simplify the matter, I first thought of a population of bugs that tasted okay. Then one individual bug in that population turns up with a genetic mutation that gave it all-out horrible taste, that a predator would reject. This is unrealistic, because the development of the foul taste would probably come in increments, rather that all at once.
If the predator spit the bug out and it survived to breed, then natural selection has occurred, and the beneficial foul taste gets passed on. If the bug dies then it depends on the other bugs carrying the same mutation to spread it through neutral drift until selection on the population occurs.
Some molecules can have a significantly different taste with only one molecule change, urea for example.
Enjoy.

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 18 by InGodITrust, posted 03-17-2010 5:09 AM InGodITrust has replied

Replies to this message:
 Message 25 by Dr Jack, posted 03-17-2010 1:01 PM RAZD has replied
 Message 27 by InGodITrust, posted 03-17-2010 2:41 PM RAZD has seen this message but not replied

  
RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 24 of 47 (550706)
03-17-2010 12:59 PM
Reply to: Message 19 by Wounded King
03-17-2010 5:11 AM


Re: kin selection or just evolution in sub-populations?
Hi Wounded King, I considered that.
I'm not sure what you think is the difference between your answer and ours, you have just swapped 'sub-population' in to represent the population of more closely related organisms, but the chances are that the sub-populations where these traits are prevalent will be more closely related individuals since we know that many of them at least share the trait for unpalatability and individuals within the same area are also normally more likely to be related.
Agreed, however I think applying kin selection to bugs is diluting the concept of organisms acting intentionally to benefit siblings, aunts, uncles, parents, and cousins. I don't see bugs as being aware of kinship, nor do I see this selection as being based on the actions of any one bug to benefit another.
The isssue is why does a trait prevail when it doesn't directly benefit the individual exhibiting that trait, the answer is kin selection. If you want to claim that none of the individuals exhibiting the same trait in the sub-population are related, or that they are generally no more related than with individuals of another sub population, then I think you will have a hard row to hoe.
Genetic drift of neutral mutations is a more general pattern than kin selection, and fits this situation better, imho.
Enjoy.

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

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Dr Jack
Member
Posts: 3514
From: Immigrant in the land of Deutsch
Joined: 07-14-2003
Member Rating: 8.7


Message 25 of 47 (550707)
03-17-2010 1:01 PM
Reply to: Message 23 by RAZD
03-17-2010 12:52 PM


Re: evolution is in populations not in individuals
Hi RAZD,
I find the concept of bugs having an awareness of kin to be somewhat problematical, and to me kin selection only works when one is aware of kinship at some level.
Kin Selection does not require any awareness of kin/non-kin only that the feature selected increases the survival probability of other carriers of the gene.

This message is a reply to:
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Replies to this message:
 Message 28 by RAZD, posted 03-17-2010 2:44 PM Dr Jack has replied

  
Dr Jack
Member
Posts: 3514
From: Immigrant in the land of Deutsch
Joined: 07-14-2003
Member Rating: 8.7


Message 26 of 47 (550708)
03-17-2010 1:03 PM
Reply to: Message 24 by RAZD
03-17-2010 12:59 PM


Wot no adaptation?
Genetic drift of neutral mutations is a more general pattern than kin selection, and fits this situation better, imho.
Wait, what? Are you suggesting that the explaination for foul tasting insects is genetic drift? That this feature is not adaptive?

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InGodITrust
Member (Idle past 1669 days)
Posts: 53
From: Reno, Nevada, USA
Joined: 05-02-2009


Message 27 of 47 (550716)
03-17-2010 2:41 PM
Reply to: Message 23 by RAZD
03-17-2010 12:52 PM


Re: evolution is in populations not in individuals
RAZD, in my last post I wrote: "It doesn't seem to me that the spread of neutral mutations, in this case, can be considered natural selection. It is chance."
This was a hasty and poorly thought out response to your post, and I feel stupid now that I've thought about it more. For some reason I was thinking that neutral mutations didn't "count" in natural selection. But they have been "judged" by nature and found neutral, and can spread and come into play later.
IGIT

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RAZD
Member (Idle past 1404 days)
Posts: 20714
From: the other end of the sidewalk
Joined: 03-14-2004


Message 28 of 47 (550717)
03-17-2010 2:44 PM
Reply to: Message 25 by Dr Jack
03-17-2010 1:01 PM


Re: evolution is in populations not in individuals
Hi Mr jack
Kin Selection does not require any awareness of kin/non-kin only that the feature selected increases the survival probability of other carriers of the gene.
Then you have watered kin selection down to common ancestry, an already adequate explanation for the transmission of genes from parents to offspring where there is no action taken by, or any different behavior of, any of the carriers to enhance the survival or breeding of their kin other than surviving and breeding.
With this definition of kin selection there is no point in saying kin selection is a mechanism.
For me, kin selection is an active behavior that benefits direct kin, such as nit-picking on siblings, mates and other family members in primates. Your definition makes no distinction between this and doing nothing, a distinct loss in descriptive ability.
Message 26:
Genetic drift of neutral mutations is a more general pattern than kin selection, and fits this situation better, imho.
Wait, what? Are you suggesting that the explaination for foul tasting insects is genetic drift? That this feature is not adaptive?
Initially - and the topic issue is initially, not a fully developed trait - it is not adaptive if the bug in question is killed while other similar looking bugs do not have a foul taste. For the foul tasting to spread wide enough in the population when all predation is lethal with no feed-back, genetic drift within the population is the only way the mutation spreads. If 10% of the population is subject to predation and there is no statistical difference between death to the initial foul bugs compared to the non-foul tasting bugs, then there is no selection.
It is only when the proportion of foul-tasting bugs within the population increases to the point where the predator associates the foul taste with enough members of the population that they are reluctant to attack the bugs that selection begins to take effect.
Genetic drift gets you to that point. Kin selection doesn't, nor does kin selection explain that at that point all members of the population benefit, fellow foul-tasting kin or not.
Enjoy.
Edited by RAZD, : clrty in last

we are limited in our ability to understand
by our ability to understand
Rebel American Zen Deist
... to learn ... to think ... to live ... to laugh ...
to share.


• • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •

This message is a reply to:
 Message 25 by Dr Jack, posted 03-17-2010 1:01 PM Dr Jack has replied

Replies to this message:
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InGodITrust
Member (Idle past 1669 days)
Posts: 53
From: Reno, Nevada, USA
Joined: 05-02-2009


(1)
Message 29 of 47 (550718)
03-17-2010 2:58 PM
Reply to: Message 21 by Dr Jack
03-17-2010 5:50 AM


Re: evolution is in populations not in individuals
Mr. Jack: After more thought, I now see how exaptation together with kin selection is a plausible explanation.
Well, you can probably see that I am hoping to find chinks in the armour of the ToE, and I haven't found one here. I don't really expect that I will ever find a chink myself, but I'm sure they exist, and will be discovered by scientists some day.
Thanks again to everyone.
IGIT

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Dr Jack
Member
Posts: 3514
From: Immigrant in the land of Deutsch
Joined: 07-14-2003
Member Rating: 8.7


(1)
Message 30 of 47 (550719)
03-17-2010 3:32 PM
Reply to: Message 28 by RAZD
03-17-2010 2:44 PM


Re: evolution is in populations not in individuals
Hi RAZD,
Then you have watered kin selection down to common ancestry,
an already adequate explanation for the transmission of genes from parents to offspring where there is no action taken by, or any different behavior of, any of the carriers to enhance the survival or breeding of their kin other than surviving and breeding.
With this definition of kin selection there is no point in saying kin selection is a mechanism.
No.
Standard selection applies because an organism with an adaptive features produces more offspring that those without; kin selection applies not to the organism itself, or its direct descendents, but to other carriers of the gene.
Do you see the distinction?
It is only when the proportion of foul-tasting bugs within the population increases to the point where the predator associates the foul taste with enough members of the population that they are reluctant to attack the bugs that selection begins to take effect.
Genetic drift gets you to that point. Kin selection doesn't, nor does kin selection explain that point all members of the population benefit at that point, fellow foul-tasting kin or not.
But we didn't suggest that kin selection gets you to that point, either. How are you explaining how it gets from there to a trait common to the population if not kin selection?

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 Message 28 by RAZD, posted 03-17-2010 2:44 PM RAZD has not replied

  
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