About mutualism between human and E.coli

[dttom]

I have just read the chapter thirteen of the selfish gene written by Richard Dawkins, it is about extended phenotype of genes. Also, it has been suggested that mutualism could have evolved from parasitism by both the so-called parasite and the host have the same means for propagation. This leads me to think about the mutualism between human and E.coli. I have tried to explain the relationship between two of them in the following way. Could any one take a look and comment on it?

Here is the passage:

E.coli is a bacteria which live in the human large intestine and is well adapted the the environment of human large intestine, where they could attain a higher reproductive rate. Human being provide E.coli a suitable environment for their growth and reproduction, in return, E.coli provides human with extra vitamine K and better absorption fo nutrients.

From Richard Dawkins, parasite which have common interest with its host would have their relationship shift from parasitism to mutualism; that, any gene carried in the 'parasite''s body which could increase the rate of propagation of genes in host would lead to increase in propagation rate of the host, which in turns such gene in that 'parasite' would be propagated with the dispersal of the host's genes, thus, as time passes by, relationship

between two entities would become mutualism instead of parasitism.

E.coli reproduce in human's large intestine and hence their interest would probably be in keeping the human body intact for a longer time so that large intestine, as the habitat or the place where E.coli live, could be maintained for longer period of time which is advantageous to E.coli; for human, which reproduce sexually, their interest should be on reproduction using sperms or eggs, given that E.coli provide a body with extra nutrients, one could survive better than rival which does not have E.coli 'parasited', so that the one with E.coli parasited would be healthier and develop more attractive secondary sexual characteristics or other features which would better attract opposite sex hence increasing the successful reproductive rate, in this way, human's interest, which lies on sexual reproduction, could be flavoured by the production of extra nutrients by E.coli. Thus, the bacteria on one side increase the reproductive rate of human being, which also increase the expected lifespan of human being which in turns leads to better reproductive environment of the bacteria, thus forming mutualistic relationship.

[ecoli]

Looks about right to me... and I'm E.coli, so I would know ;-)

 

Just be careful when using word's like "interest." Because, while the evolutionary imperitave exists, its not really a concious decision being made. Rather, as you have said, advantageous traits that are being passed on.

Also consider the fact that humans don't have any concious choice to what lives in their gut. Soon after birth, E. coli begin to colonize the human intestines. This relationship is also exhibited by other animal species as well, soI'm pretty sure that this mutualistic symbiosis existed before humans evolved, and that this mutualism was simply carried over as the speicies evolved.

 

I'm 100% sure about this last bit, though.

 

PS - human body core temperature is ~37C, which just happens to be the temp at which e. coli grows the best. Coincidence or evolution?

[YT2095]

ecoli IS a Mutant, don`t let his sweet words fool you!

[foodchain]

I have just read the chapter thirteen of the selfish gene written by Richard Dawkins, it is about extended phenotype of genes. Also, it has been suggested that mutualism could have evolved from parasitism by both the so-called parasite and the host have the same means for propagation. This leads me to think about the mutualism between human and E.coli. I have tried to explain the relationship between two of them in the following way. Could any one take a look and comment on it?

Here is the passage:

E.coli is a bacteria which live in the human large intestine and is well adapted the the environment of human large intestine, where they could attain a higher reproductive rate. Human being provide E.coli a suitable environment for their growth and reproduction, in return, E.coli provides human with extra vitamine K and better absorption fo nutrients.

From Richard Dawkins, parasite which have common interest with its host would have their relationship shift from parasitism to mutualism; that, any gene carried in the 'parasite''s body which could increase the rate of propagation of genes in host would lead to increase in propagation rate of the host, which in turns such gene in that 'parasite' would be propagated with the dispersal of the host's genes, thus, as time passes by, relationship

between two entities would become mutualism instead of parasitism.

E.coli reproduce in human's large intestine and hence their interest would probably be in keeping the human body intact for a longer time so that large intestine, as the habitat or the place where E.coli live, could be maintained for longer period of time which is advantageous to E.coli; for human, which reproduce sexually, their interest should be on reproduction using sperms or eggs, given that E.coli provide a body with extra nutrients, one could survive better than rival which does not have E.coli 'parasited', so that the one with E.coli parasited would be healthier and develop more attractive secondary sexual characteristics or other features which would better attract opposite sex hence increasing the successful reproductive rate, in this way, human's interest, which lies on sexual reproduction, could be flavoured by the production of extra nutrients by E.coli. Thus, the bacteria on one side increase the reproductive rate of human being, which also increase the expected lifespan of human being which in turns leads to better reproductive environment of the bacteria, thus forming mutualistic relationship.

 

Have you studied any other symbiotic relationships besides this one? Not that it would have any impact, just a question. Mutualism applies a benefit to all parties involved while parasitism is only a benefit of say one of the two in this instance. It would make sense to me though that the e.coli would have had to be able to keep homeostasis not only for itself but its host at conditions that would allow for survival to continue, or the host itself would have to keep stable in regards to health or find a way to reach it with a parasite over time. So in this instance the ecology or physical environment providing for natural selection would be for two organisms at once? Where the visibility comes into play on how this would reach a mutualistic end I guess is provided by the idea they both provide for larger rates of gene propagation. This is somewhat interesting as it would imply to me of maybe the bridge from prokaryote to eukaryote via different symbiotic relationships possibly, and this is why I would like to know how many relationships like this you have studied.

 

I agree to a certain extent with the selfish gene theory, though I have not fully studied anywhere close to all the research that exists to support such, or the stuff that occurs weather I get it or not so to speak. I think it detracts from looking at the organism in total and in essence only favoring part of it over the rest in terms of explanation, such as maybe its selfish RNA.

[dttom]

Thanks for all comments...

This passage is written after I have read Dawkins' allegation about two organisms with the same methods of propagation on the same 'machine' would gradually shift their relationship from parasitism to mutualism, and it is an example which I suddenly think of, so I then tried to apply the idea of his to explain the relationship between human and E.coli.

[lucaspa]

Thanks for all comments...

This passage is written after I have read Dawkins' allegation about two organisms with the same methods of propagation

 

Are you sure E. coli and humans have the "same methods of propagation"? After all, humans reproduce sexually while E. coli reproduce asexually.

 

Those individual parasites that cause the least harm to their hosts will be selected. Any individual parasite that causes the premature death of its host creates a crisis for itself: the death of the host results in the death of the parasite unless the parasite has managed to colonize a new host.

 

Mutualism is simply an extension of that "do the least harm" to "do some good". Individuals that help the host will then have a healthier host with more spare resources for the parasite. Those individuals will have a competitive advantage.

 

Eventually the cost of producing the benefit to the host will equal the increased resources from the host and, at that point, the mutualism should reach a stable equilibrium.

[Paralith]

Are you sure E. coli and humans have the "same methods of propagation"? After all, humans reproduce sexually while E. coli reproduce asexually.

 

I don't think he's saying that they have the same kind of reproduction; rather, both E. coli reproduction and human reproduction are dependent on the human staying alive and healthy; they both require the same thing in order to propagate.

[immortal]

I think Symbiosis evolved bit earlier than everyone would have thought. The fact that the mitochondria have their own DNA suggests that once these were independently living and somehow got inside the eucaryotic cells and exchanged genes. The endosymbiosis theory explains that.

E.coli doesn't always stay in symbiosis with the humans if it gets access to the urinary bladder it causes a disease called cystitis. E.coli has to maintain its ecosystem (i.e. host) in order to stay alive and replicate. Quorum sensing is a wonderful example of symbiosis. Genes sometimes can be altruistic.

[lucaspa]

I don't think he's saying that they have the same kind of reproduction; rather, both E. coli reproduction and human reproduction are dependent on the human staying alive and healthy; they both require the same thing in order to propagate.

 

That would make more sense.

[lucaspa]

I think Symbiosis evolved bit earlier than everyone would have thought. The fact that the mitochondria have their own DNA suggests that once these were independently living and somehow got inside the eucaryotic cells and exchanged genes. The endosymbiosis theory explains that.

E.coli doesn't always stay in symbiosis with the humans if it gets access to the urinary bladder it causes a disease called cystitis. E.coli has to maintain its ecosystem (i.e. host) in order to stay alive and replicate. Quorum sensing is a wonderful example of symbiosis. Genes sometimes can be altruistic.

 

First, Dawkins is wrong with selfish gene. Genes cannot be the unit of selection.

 

Second, natural selection can never produce anything purely altruistic. There must always be a selfish component. Darwin himself stated this and used pure altruism as a way to falsify natural selection.

 

Third, yes, symbiosis seems to have been around for a long time, since mitochondria and chloroplasts seem to have resulted from single celled organisms becoming incorporated into other single celled organisms and acting as organelles. It's not only that they have their own DNA, but that ribosomes within them have prokaryotic subunits and differ from the ribosomes in the cytoplasm. I'm not sure this is before "everyone would have thought". Remember, there is 3.2 billion years between the oldest fossils known and the beginning of the Cambrian. That is over 5x the time between the Cambrian and present. LOTS of time for evolution of many things -- such as the common metabolic pathways and endosymbiosis.

 

Fourth, yes, E. coli can sometimes become toxic, even within the GI tract. There are strains(species) of E. coli that are fatal to humans. And example is a recent strain that has the ability to live in an acidic environment, such as apple juice. While the variation opens up new food sources for that strain, the strain itself is now toxic to humans and has resulted in over 100 fatalities to their hosts.

 

Fifth, quorum sensing is not symbiosis, but rather an intermediate step to multicellularity. The bacteria are acting somewhat as a multicelled organism. And there is obviously a selfish component to quorum sensing. Each and every single bacteria benefits from it in some form -- either in gaining access to food or in avoiding death.

[immortal]

First, Dawkins is wrong with selfish gene. Genes cannot be the unit of selection.

Second, natural selection can never produce anything purely altruistic. There must always be a selfish component. Darwin himself stated this and used pure altruism as a way to falsify natural selection.

 

Fifth, quorum sensing is not symbiosis, but rather an intermediate step to multicellularity. The bacteria are acting somewhat as a multicelled organism. And there is obviously a selfish component to quorum sensing. Each and every single bacteria benefits from it in some form -- either in gaining access to food or in avoiding death.

 

First, everything makes perfect sense when you think at a gene level, evolution is all about survival of the genes, the mutations happens to genes and the genes (i.e.individual) with positive mutations gets selected and not the species. The species is selected only after the individual has passed this mutant genes.

Here is a link which suggests that positive selection of a single gene can create new species.

http://www.nature.com/ng/journal/v30/n4/abs/ng852.html

 

Second, yes there is always a selfish component, for example:- why do male honey bees sting even after knowing that losing their fangs would kill them, they sting because they are sterile they can't produce offsprings. So saving the colony is their ultimate goal.

 

Fifth, Bacterias communicate with each other with chemical substances called 'pheromones'. I do agree that they act as multicellular but you can't say this has 'not symbiosis' any mutual relationship with different species for the welfare of each other is called symbiosis. Symbiosis is not only seen in bacterias, for example:- Quorum sensing bacterias stay in symbiosis with fishes the bacterias provide light for the fish to catch prey and the fish gives shelter. I do agree that this is not purely altruistic.

[lucaspa]

First, everything makes perfect sense when you think at a gene level, evolution is all about survival of the genes, the mutations happens to genes and the genes (i.e.individual) with positive mutations gets selected and not the species. Here is a link which suggests that positive selection of a single gene can create new species.

http://www.nature.com/ng/journal/v30/n4/abs/ng852.html

 

Species don't get selected. Individuals do. IOW, the entire genome.

 

I'll let Ernst Mayr explain the problem of Dawkins' reductionist version:

 

"Much confusion about this problem can be avoided by considering two separate aspects of the question: 'selection of' and 'selection for'. Let us illustrate this with the sickle cell gene. For the question 'selection of' the answer is the individual who either does or does not carry the sickle cell gene. In a malalrial region the answer to 'selection for' is the sickle cell gene, owing to the protection it gives to its heterogenous carriers. When one makes the distinction between the two questions, it becomes quite clear that a gene as such can never be the object of selection. It is only part of a geneotype, whereas the phenotypes of the individual as a whole (based upon the genotype) is the actual object of selection (Mayr 1997). ...

"The reductionist [Dawkins'] thesis that the gene is the object of selection is also invalid for another reason. It is based on the assumption that each gene acts independently of all other genes when making its contribution of genes to the properties of the phenotype. If this were true, the total contribution of genes to the making of the phenotype would be accounted for by the addition of the action of all individual genes. This assumption is referred to as the 'additive gene action' assumption. Indeed, some genes, perhaps even many genes, seem to act in such a direct and independent manner. If you are a male with the hemophiliac gene, you will be a bleeder. Many other genes, however, interact with each other. Gene B may enhance or reduce the effects of gene A. Or else the effects of gene A will not occur unless gene B is also present. Such interactions among genes are called epistatic interactions." Ernst Mayr What Evolution Is, pgs 126-127

 

Second, yes there is always a selfish component, for example:- why do male honey bees sting even after knowing that losing their fangs would kill them, they sting because they are sterile they can't produce offsprings. So saving the colony is their ultimate goal.

 

Sorry, but "saving the colony" isn't the ultimate goal. Read EO Wilson's work. What the honeybee does is save its relatives. In terms of the Dawkins' reductionism you like, saving 2 siblings = saving yourself because those siblings will have the equivalent of your genes. The goal is saving their genes. It just so happens that the members of the colony are all siblings because the queen lays many eggs from one mating with a drone.

 

Fifth, Bacterias communicate with each other with chemical substances called 'pheromones'. I do agree that they act as multicellular but you can't say this has 'not symbiosis' any mutual relationship with different species for the welfare of each other is called symbiosis. Symbiosis is not only seen in bacterias, for example:- Quorum sensing bacterias stay in symbiosis with fishes the bacterias provide light for the fish to catch prey and the fish gives shelter. I do agree that this is not purely altruistic.

 

Quorum sensing is for the benefit of the bacteria species. That is, within the species.

 

There are 2 separate things happening with the V. fischeri bacteria. The bacteria are in symbiosis with the squid. However, the quorum sensing within the bacterial population is not symbiosis. Rather, the cost of producing luciferase by individual V. fischeri is greater than any benefit of glowing for the individual. Remember, there are V. fischeri that are free swimming. The benefit of glowing ONLY comes when the V. fischeri are concentrated in the photophore of the squid. And that is when quorum sensing comes in: the concentration of chemical is high enough to cause transcription of the gene for luciferase.

 

So, the quorum sensing itself isn't symbiosis, but in this case aids the symbiotic relationship of V. fischeri and squid. Thus the quorum sensing happens within the V. fischeri to benefit the V. fischeri. Producing luciferase is part of the symbiotic relationship of V. fischeri to the squid. If you want to check my source:

 

"Quorum sensing was first observed in Vibrio fischeri, a bioluminiscent bacterium that lives as a symbiont in the light-producing organ of the Hawaiian bobtail squid. When V. fischeri cells are free-living (or planktonic), the autoinducer is at low concentration and thus cells do not luminesce. In the light organ of the squid (photophore), they are highly concentrated (about 1011 cells/ml) and transcription of luciferase is induced, leading to bioluminescence."

http://en.wikipedia.org/wiki/Quorum_sensing

[lucaspa]

Here is a link which suggests that positive selection of a single gene can create new species.

http://www.nature.com/ng/journal/v30/n4/abs/ng852.html

 

Immortal, I'm afraid the paper doesn't show what you claim it does. It is an important paper for evolution, because it shows 1) increase in information, 2) formation of a new trait by duplication of genes. The key sentences in the Abstract are: "We show that RNASE1B has evolved rapidly under positive selection for enhanced ribonucleolytic activity in an altered microenvironment, a response to increased demands for the enzyme for digesting bacterial RNA. At the same time, the ability to degrade double-stranded RNA, a non-digestive activity characteristic of primate RNASE1, has been lost in RNASE1B, indicating functional specialization and relaxation of purifying selection. Our findings demonstrate the contribution of gene duplication to organismal adaptation"

 

Look at the bold. That is the real key. Speciation requires reproductive isolation and this paper doesn't address that. There is no indication that RNASE1B causes reproductive isolation between duoc langur monkeys and any other species.

 

There are studies looking at the genes that do change during reproductive isolation:

 

1. M Nei and J Zhang, Evolution: molecular origin of species. Science 282: 1428-1429, Nov. 20, 1998. Primary article is: CT Ting, SC Tsaur, ML We, and CE Wu, A rapidly evolving homeobox at the site of a hybrid sterility gene. Science 282: 1501-1504, Nov. 20, 1998.

[Paralith]

I'll let Ernst Mayr explain the problem of Dawkins' reductionist version:

 

"Much confusion about this problem can be avoided by considering two separate aspects of the question: 'selection of' and 'selection for'. Let us illustrate this with the sickle cell gene. For the question 'selection of' the answer is the individual who either does or does not carry the sickle cell gene. In a malalrial region the answer to 'selection for' is the sickle cell gene, owing to the protection it gives to its heterogenous carriers. When one makes the distinction between the two questions, it becomes quite clear that a gene as such can never be the object of selection. It is only part of a geneotype, whereas the phenotypes of the individual as a whole (based upon the genotype) is the actual object of selection (Mayr 1997). ...

"The reductionist [Dawkins'] thesis that the gene is the object of selection is also invalid for another reason. It is based on the assumption that each gene acts independently of all other genes when making its contribution of genes to the properties of the phenotype. If this were true, the total contribution of genes to the making of the phenotype would be accounted for by the addition of the action of all individual genes. This assumption is referred to as the 'additive gene action' assumption. Indeed, some genes, perhaps even many genes, seem to act in such a direct and independent manner. If you are a male with the hemophiliac gene, you will be a bleeder. Many other genes, however, interact with each other. Gene B may enhance or reduce the effects of gene A. Or else the effects of gene A will not occur unless gene B is also present. Such interactions among genes are called epistatic interactions." Ernst Mayr What Evolution Is, pgs 126-127

 

I have a question for you. I agree with what's quoted here - but I have also heard that certain genes may have physical qualities then enable them to be passed on to the next generation more than other genes; e.g., the genes are competing between each other at the molecular level to get passed on, and in that case the genes themselves are actually the objects of selection. I don't know much about this, though, it's mostly vague memories from my genetics class several years ago. I'm curious if you've heard about it, and/or what your opinion of it is?

[immortal]

...

 

Quorum sensing is for the benefit of the bacteria species. That is, within the species.

 

 

But Biofilms do have different species of bacterias and also algae, protozoa and fungi etc.. which use Quorum sensing.

[immortal]

Species don't get selected. Individuals do. IOW, the entire genome.

 

I'll let Ernst Mayr explain the problem of Dawkins' reductionist version:

 

"Much confusion about this problem can be avoided by considering two separate aspects of the question: 'selection of' and 'selection for'. Let us illustrate this with the sickle cell gene. For the question 'selection of' the answer is the individual who either does or does not carry the sickle cell gene. In a malalrial region the answer to 'selection for' is the sickle cell gene, owing to the protection it gives to its heterogenous carriers. When one makes the distinction between the two questions, it becomes quite clear that a gene as such can never be the object of selection. It is only part of a geneotype, whereas the phenotypes of the individual as a whole (based upon the genotype) is the actual object of selection (Mayr 1997). ...

"The reductionist [Dawkins'] thesis that the gene is the object of selection is also invalid for another reason. It is based on the assumption that each gene acts independently of all other genes when making its contribution of genes to the properties of the phenotype. If this were true, the total contribution of genes to the making of the phenotype would be accounted for by the addition of the action of all individual genes. This assumption is referred to as the 'additive gene action' assumption. Indeed, some genes, perhaps even many genes, seem to act in such a direct and independent manner. If you are a male with the hemophiliac gene, you will be a bleeder. Many other genes, however, interact with each other. Gene B may enhance or reduce the effects of gene A. Or else the effects of gene A will not occur unless gene B is also present. Such interactions among genes are called epistatic interactions." Ernst Mayr What Evolution Is, pgs 126-127

 

 

 

Sorry, but "saving the colony" isn't the ultimate goal. Read EO Wilson's work. What the honeybee does is save its relatives. In terms of the Dawkins' reductionism you like, saving 2 siblings = saving yourself because those siblings will have the equivalent of your genes. The goal is saving their genes. It just so happens that the members of the colony are all siblings because the queen lays many eggs from one mating with a drone.

 

 

 

 

Natural selection acts on genes, not on species or individual. And similarly the 'fittest' that do the surviving are the fittest genes or rather the fittest genotypes, rather than the fittest individuals remember individuals die at the end; genes don't. I am not saying that you are wrong I do know that there is not a single gene that determines your height or hair colour its more like a gene complex that interacts with each other. The sefish gene theory looks on a genes point of view it does not rejects Darwinism but it adds to it. Dawkins says neither of the theories are right or wrong; they are equivalent.

You can look at evolution in two ways on a genes angle and on a organisms point of view.

 

Genes don't have control over the individual. Genes control by protein synthesis which is powerful but slow. But behaviour is very quick for example; you have to choose a mate and you know that you have to choose the best one's and reject the odd one's it would take time for the genes to make the choice but your instincts does it more quickly. Genes don't make choices for us but it will surely make us feel for the choices we make for example; novelty genes.

 

Well does an honey bee know to which species it belongs to and which are'nt. The honey bees don't save their relatives but save the colony and saving the colony is equivalent to saving their genes. Remember Evolution is not for the good of the species it is for the good of the genes.

[immortal]

Immortal, I'm afraid the paper doesn't show what you claim it does. It is an important paper for evolution, because it shows 1) increase in information, 2) formation of a new trait by duplication of genes. The key sentences in the Abstract are: "We show that RNASE1B has evolved rapidly under positive selection for enhanced ribonucleolytic activity in an altered microenvironment, a response to increased demands for the enzyme for digesting bacterial RNA. At the same time, the ability to degrade double-stranded RNA, a non-digestive activity characteristic of primate RNASE1, has been lost in RNASE1B, indicating functional specialization and relaxation of purifying selection. Our findings demonstrate the contribution of gene duplication to organismal adaptation"

 

Look at the bold. That is the real key. Speciation requires reproductive isolation and this paper doesn't address that. There is no indication that RNASE1B causes reproductive isolation between duoc langur monkeys and any other species.

 

There are studies looking at the genes that do change during reproductive isolation:

 

1. M Nei and J Zhang, Evolution: molecular origin of species. Science 282: 1428-1429, Nov. 20, 1998. Primary article is: CT Ting, SC Tsaur, ML We, and CE Wu, A rapidly evolving homeobox at the site of a hybrid sterility gene. Science 282: 1501-1504, Nov. 20, 1998.

 

I apologise I was in a hurry and I do know that there are studies on speciation for example; the study of the phenomenon of ring species on some insect eating birds called warblers. Species is a human idea not a natural force. A individual is either undergoing speciation or has the potential for speciation. We are intermediates.

[Paralith]

Well does an honey bee know to which species it belongs to and which are'nt. The honey bees don't save their relatives but save the colony and saving the colony is equivalent to saving their genes. Remember Evolution is not for the good of the species it is for the good of the genes.(emphasis mine - paralith)

 

Exactly. And the honeybee has genes that "tell" it to work for the good of the colony, because the members of the colony have those same genes, so if the honeybee dies but in doing so saves other members of the colony who go on to reproduce, it has albeit indirectly ensured the transfer of its genes to the next generation. Genes that will again "tell" the next generation of bees to work for the good of the colony. That's the point of saving relatives. Relatives have some of the same genes as you. And in the case of many species of bee, sometimes almost all of them have the exact same genes as you.

 

Species is a human idea not a natural force. A individual is either undergoing speciation or has the potential for speciation. We are intermediates.

 

Isn't the definition of speciation the forming of a new species? You can't say species aren't a reality and then go on to describe reality using a term dependent on the existence of species. Just playin' the devil's advocate here. I understand what you're trying to say; but the idea of a species is a tool to help us better understand evolution, and I think can be applicable as long as it is understood that not all organisms can be defined as a finite species.

[lucaspa]

Natural selection acts on genes, not on species or individual.

 

Go back and read Mayr again. Natural selection acts "on" the individual. It is the individual that is selected. That is, it is the bundle of genes that is the individual. The selfish gene theory doesn't work because of the reasons Mayr gave. No one is saying that Dawkins is against Darwinism, just that Dawkins is wrong in this particular area.

 

And similarly the 'fittest' that do the surviving are the fittest genes or rather the fittest genotypes, rather than the fittest individuals remember individuals die at the end; genes don't.

 

The competition for scarce resources that is the "struggle for existence" takes place among individual organisms, not among single genes. Yes, individuals die, but so do alleles (forms of genes). Some alleles are eliminated from the population altogether and, thus, don't exist anymore.

 

And yes, it is the fittest individuals that do the surviving and leave more copies of an allele (in their offspring) in the next generation. A single gene cannot survive; alleles only survive as members of a genome.

 

Genes don't have control over the individual. Genes control by protein synthesis which is powerful but slow. But behaviour is very quick for example;

 

Behavior is influenced by genes. And protein synthesis takes place in only a few seconds!

 

you have to choose a mate and you know that you have to choose the best one's

 

That italics is wrong. No, you do NOT "know" that you have to choose the best one. Not in an evolutionary sense. You are imparting conscious choice of the individual in evolution, and Darwinism shows that is not the case.

 

Genes don't make choices for us but it will surely make us feel for the choices we make for example; novelty genes.

 

Again, that isn't what evolution says. We don't choose our alleles. We are either lucky enough to be born with a set of alleles that allows us to do well in the struggle for existence, or we are not. We don't choose novelty or novel alleles; we are born with them.

 

It turns out that sexual selection is tied to survival traits. For a long time it was thought that sexual selection was distinct from survival traits, such that mate selection (such as female peacocks selecting for extravagant tails in the males) was actually picking maladaptive alleles. More recent studies have shown that, most often, alleles for mate selection are packaged with other alleles for adaptive traits. A paper looking this is:

3. E Pennisi, Females pick good genes in frogs, flies. Science 280:1837-1838, (19 June) 1998. Discusses recent studies that show how "bad" genes associated with male display are actually connected to survival genes in males, so that females actually pick survival traits. In frogs the descendents of "long callers" did better in every fitness test.

 

Well does an honey bee know to which species it belongs to and which are'nt. The honey bees don't save their relatives but save the colony and saving the colony is equivalent to saving their genes.

 

And saving their relatives is WHY honeybees save the colony. They don't save the colony because it is the colony, but because the members of the colony are all siblings. In saving their relatives they are also saving the alleles that they have.

 

Evolution is not for the good of the species it is for the good of the genes.

 

That is Dawkins' view again, and it is fundamentally flawed. For the reasons Mayr stated. Also consider: 99% of all species have gone extinct -- which means their genes have gone extinct. If evolution is "for the good of the genes", then it doesn't work very well, does it?

 

Dawkins made two fundamental errors:

1. Confused "selection of" and "selection for".

2. Ascribed consciousness to evolution. In this case, the "consciousness" is said to be in the genes.

 

Unfortunately, what Dawkins did was write a book about his ideas for the lay public before those ideas were thoroughly tested by evolutionary biologists. Thus we have the situation now where we have a lot of lay people who took Dawkins at his word and think he was right. They haven't looked at the community of evolutionary biologists -- such as Mayr -- to see whether Dawkins really was correct. And he wasn't. Mayr didn't write for the lay public; he wrote for fellow evolutionary biologists. Only in his last book What Evolution IS did Mayr address a book to non-biologists. I strongly suggest you read that book, because some of your ideas on what evolution is are incorrect. I can see where you got them, but that doesn't change that you were misinformed.

[lucaspa]

I apologise I was in a hurry and I do know that there are studies on speciation for example; the study of the phenomenon of ring species on some insect eating birds called warblers. Species is a human idea not a natural force. A individual is either undergoing speciation or has the potential for speciation. We are intermediates.

 

Oh boy!

 

1. Species is the ONLY biological reality. Higher taxa are human ideas, not biological reality. Genera, families, orders, etc. are simply groups of species.

 

Species cannot be precisely defined because evolution is true. Populations are transforming from one species to another over generations. We can see at generation 1 we have species A and at generation 1,000 we have species B. BUT, there is no defining moment where we can say species A became species B. That is, we CANNOT say "at generation 499 we have species A and at generation 500 we have species B". This means we cannot have a precise definition for "species". Whatever definition you use, you will always be able to find a population that is somewhere in-between.

 

So, species are real. But we cannot make a precise definition of species.

 

The issue was your thought that changing one gene from one allele to another made a new species. That doesn't happen, either. Speciation involves changes to more than one gene.

 

2. Individuals do NOT undergo speciation. Speciation happens to populations. I cannot emphasize that enough: evolution happens to populations.

 

As an individual, I have no potential for speciation nor am undergoing speciation. I am born with the alleles I have and those cannot change during my lifetime. Only the population has its genetic composition change over generations.

 

And no, not every population is in the process of transforming to a new species. Remember, 99+% of all species have gone extinct. That means that those species did not form a new species, but instead ended. The individuals in them were not intermediate to anything else.

 

Also remember that, once a population is well-adapted to its environment, natural selection acts to keep the population the same and actually acts against change! It's called "purifying" or "stabilizing" selection.

 

Yes, natural selection comes in 3 forms. Directional, purifying, and disruptive. Most people only consider directional selection and don't even realize the other 2 forms exist.

[lucaspa]

I have a question for you. I agree with what's quoted here - but I have also heard that certain genes may have physical qualities then enable them to be passed on to the next generation more than other genes; e.g., the genes are competing between each other at the molecular level to get passed on, and in that case the genes themselves are actually the objects of selection. I don't know much about this, though, it's mostly vague memories from my genetics class several years ago. I'm curious if you've heard about it, and/or what your opinion of it is?

 

Again it is the confusion of "selection of" and "selection for". It is still the individual that is the object OF selection. But the particular allele that is being selected FOR.

 

I'm not sure what you are referring to competition between genes and "passed on to the next generation more than other genes". As you said it, that would imply alleles that prevent copying of the other chromosome during meiosis so that only 1 chromosome of the pair is available in the sperm or ova. I haven't seen anything about that.

 

I have seen papers about competition among sperm. In species where multiple males mate with a fertile female, there is competition between the sperm as to which one is going to fertilize the ovum. In those cases there are alleles that block sperm from other individuals.

 

12. Torgerson DG, Kulathinal RJ, Singh RS. Mol Biol Evol. 2002 Nov;19(11):1973-80. Mammalian sperm proteins are rapidly evolving: evidence of positive selection in functionally diverse genes.

10. Swanson WJ, Nielsen R, Yang Q. Mol Biol Evol. 2003 Jan;20(1):18-20. Pervasive adaptive evolution in Mammalian fertilization proteins.

[lucaspa]

But Biofilms do have different species of bacterias and also algae, protozoa and fungi etc.. which use Quorum sensing.

 

SOME biofilms involve more than one species. In this case, we are still dealing more akin to multicellular organisms where we have specialized organs. The quorum sensing is helping build the "organ" -- biofilm -- from several "tissue types" -- the species. It is more similar to building a liver from the ductal cells, blood vessels, stromal cells, and the hepatocytes. At least 6 different phenotypes (species) making one organ.

[immortal]

SOME biofilms involve more than one species. In this case, we are still dealing more akin to multicellular organisms where we have specialized organs. The quorum sensing is helping build the "organ" -- biofilm -- from several "tissue types" -- the species. It is more similar to building a liver from the ductal cells, blood vessels, stromal cells, and the hepatocytes. At least 6 different phenotypes (species) making one organ.

 

Then why it can't be symbiosis without quorum sensing there can't be biofilms. I read somewhere that you are studying symbiotic relationships. So do organisms show reciprocal altruism i.e. I help you today hoping that you will help me in the future and thanks for the advice.

[immortal]

I'm not sure what you are referring to competition between genes and "passed on to the next generation more than other genes". As you said it, that would imply alleles that prevent copying of the other chromosome during meiosis so that only 1 chromosome of the pair is available in the sperm or ova. I haven't seen anything about that.

 

 

I think he is talking about the intragenomic conflict. Even I want your opinion on this.

 

Links:

http://en.wikipedia.org/wiki/Intragenomic_conflict

[lucaspa]

Then why it can't be symbiosis without quorum sensing there can't be biofilms.

 

1. Because most biofilms involve only a single species. Symbiosis requires more than one species.

 

2. Many biofilms don't involve quorum sensing. The biofilm forms simply because there are a lot of bacteria producing what the single bacteria produces.

 

3. Even in cases where quorum sensing triggers more than one species to make the biofilm, each species does just fine without the other when they are not in the biofilm. Symbiosis means that the species require each other.

 

I read somewhere that you are studying symbiotic relationships.

 

Must be some other Paul Lucas

 

So do organisms show reciprocal altruism i.e. I help you today hoping that you will help me in the future

 

Some species do. Humans, for example. Notice that species that do exhibit such behavior also have adaptations in the individual for detecting cheating. Individuals that always help but never get help in return aren't going to last very long. OTOH individuals with the variations to detect cheating will do better.

 

I'm not aware of reciprocal altruism going beyond species boundaries. That is, an individual of one species engaging in reciprocal altruism with a member of another species. There may be a few, but I haven't run across examples yet.