# Why Do Bacteria Stay Bacteria in Evolution?

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I am relatively new to the Forum so take it easy.

However, despite the life cycle of bacteria (20 minutes per cell division in rich medium), bacteria have stayed bacteria over millions of years. They also would have more mutation due to the sheer rate of cell division than animals so why have they stayed bacteria? Also the same with flies.

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They have a niche and fill it well.

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But they can colonise any area of the world and have a high mutation rate. Why have they not developed into bacterial tissues and organs despite the millions of chances?

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There isn't a selection pressure for it. Mutation alone doesn't drive evolution.

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Some would say they already have...that's why we are more than single cell organisms.

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There isn't a selection pressure for it. Mutation alone doesn't drive evolution.

I disagree with this. Doesn't natural selection depend on the choice of the correct set of genes with correct mutations to survive in a certain place? For example, a bacterium living in hot springs would be expected to have genes mutated to help them survive in these hot spots. Evolution is entirely driven by the quality of mutations available.

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But they can colonise any area of the world and have a high mutation rate. Why have they not developed into bacterial tissues and organs despite the millions of chances?

Look at things like biofilms for something similar to tissues.

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I disagree with this. Doesn't natural selection depend on the choice of the correct set of genes with correct mutations to survive in a certain place? For example, a bacterium living in hot springs would be expected to have genes mutated to help them survive in these hot spots. Evolution is entirely driven by the quality of mutations available.

There was a selection pressure for the genes allowing extremophile behavior. Evolution is driven by the nonrandom selection of random genetic mutations.

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But they can colonise any area of the world and have a high mutation rate.

Yes Bacteria do have a high mutation rate, but mutation isn't what drives Evolution. Mutation only drives variation.

However, mutation is not the best driver of variation. Sex is the best driver (that we know of) of variation.

Bacteria reproduce asexually, this only provides a slow rate of change. It is true that most mutations are bad (in that environment - they might be good in another environment though), as this is the case, it take a long time for good mutations to accumulate in the gene pool of the organism. Some bacteria can exchange genes (a sort of a sideways transfer which is different than sex).

In Sexual reproduction there is more opportunity for variation and for good genes to accumulate as each set of genes in a sexually reproducing species comes from 2 parents, where as bacteria only have 1 parent.

In sexual reproduction the 2 parents are the result of a string of successful mutations and they then provide the offspring with 2 different sets of genes (each successful and each providing different mutations). It effectively doubles the number of mutations in the organisms family history.

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same reason there are still Apes today or Wolves even though we have Mankind and Lassie.

we just took different branches in evolution and some didnt.

That would be My guess.

I cant explain Homer Simpson however.

Edited by YT2095

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you know i'm pretty darn sure that bacteria are continually changing, this is how we develop different type of bacteria,and seriously there are billions of different types of bacteria, we don't know them all,not only that but completely new species of animals are found everyday in the rain forest, couldn't this be that they have developed into something more useful, and we simply didn't notice until they became big enough?

trace any animals ancestry back far enough and you will find a bacterial common ancestor, so technically bacteria has continually changed, we're just seeing the branch that didn't completely change or find compatibility with one another, enough to develop another organism.

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The better question is "why aren't we all bacteria" because they've done a lot better job of colonizing every conceivable niche on (and within) the earth than us multicellulars have.

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The better question is "why aren't we all bacteria" because they've done a lot better job of colonizing every conceivable niche on (and within) the earth than us multicellulars have.

I thought we were largely composed of bacteria.

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you know i'm pretty darn sure that bacteria are continually changing, this is how we develop different type of bacteria,and seriously there are billions of different types of bacteria, we don't know them all,not only that but completely new species of animals are found everyday in the rain forest, couldn't this be that they have developed into something more useful, and we simply didn't notice until they became big enough?

Forget the rainforest... we're finding new bacterial species on our own bodies!

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I am relatively new to the Forum so take it easy.

However, despite the life cycle of bacteria (20 minutes per cell division in rich medium), bacteria have stayed bacteria over millions of years. They also would have more mutation due to the sheer rate of cell division than animals so why have they stayed bacteria? Also the same with flies.

I guess it would be the same reason why we have modern extant species really. The question to me implies that for instance some new gene or protein that can convey a better fitness to an organism in a giving and possibly temporal environment will surely occur roughly the same time in all organisms of specie or at least radiate to all organisms.

I think also that you can have behavioral aspects to evolution that existed as a possibility in the environment giving a certain phenotype/genotype or organism, or that genetic variation to it did not have to occur. This is not evolution in a sense of direct but more or less a variable that can occur and would hold sway on such a process.

With that I would think its more easy to see that evolution occurring spawned primates, yet we don’t just have one specie of primate alive for life on earth total.

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I thought we were largely composed of bacteria.

Not the last time I checked... I think we've got some nuclei in our cells.

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Not the last time I checked... I think we've got some nuclei in our cells.

On a per cell basis we are, but not by weight.

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I am relatively new to the Forum so take it easy.

However, despite the life cycle of bacteria (20 minutes per cell division in rich medium), bacteria have stayed bacteria over millions of years. They also would have more mutation due to the sheer rate of cell division than animals so why have they stayed bacteria? Also the same with flies.

Some bacteria have stayed bacteria, others have become extinct, and some of those have evolved into more complex forms of life.

Currently exisiting species of bacteria do very well as they are, have little need to 'evolve' and will undoubtedly outlive humans and possibly everything else too. Being complex does not make one any better. Evolution only cares about which genes get passed on, so if the best way to get ones genes passed on is to stay as one is then there is no selective pressure to change - and quite the opposite in many cases.

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Forget the rainforest... we're finding new bacterial species on our own bodies!

i know , i was just trying to make a point, do you think the bacteria in our bodies, are perhaps evolving? that could be why we find so many new types of bacteria, like all the time.

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do you think the bacteria in our bodies, are perhaps evolving?

Yes. Absolutely!

<premptive post>

Let's remember people. We can't just make stuff up and pretend it's fact. Let's use the actual work being done in the field to answer these questions, not our own speculations. Also, if we do speculate, let's at least make sure that our premises are valid so our conclusions are as well.

</premptive post>

Edited by iNow
multiple post merged

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Bacteria and multicellular organisms have been at war with each other for several hundred million years. We have an evolutionary advantage over bacteria: sex. Bacteria, on the other hand, have an evolutionary advantage over us: short life spans and sloppy copying of genes.

And yes, bacteria are evolving inside us. Evidence: drug resistant strains of bacteria.

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It does create a paradox. Bacteria divide or reproduce very fast yet changed less than apes who reproduced much much less. The paradox continues, the bacteria's machinery for assuring exact genetic duplication is primitive and should make more mistakes compared to apes, yet apes are able to evolve faster. It appears to be an exception that breaks the rules, which is against the law. Therefore is unlawful to discuss.

I comes down to environmental potentials changing the DNA. There is no good place for bacteria to evolve in peace since they are typically surrounded by higher life forms that keeps them in their place. The places where they can live in peace are crappy environments which don't help. There is pressure from the top to keep the bottom. Bacteria turn out to be very useful slaves within the human body performing tasks without having any honor as full genetic citizen. They do rebel at times, but even medicine keeps these low life renegades in their place.

Their selective advantage is being able to make tons of these to keep ahead of extinction. They plot their revenge and try to thin out of the top to release some of the downward pressure. But apes with excellent genetic duplication and slow reproduction rates are able evolve faster because there is not much in the way of downward pressure.

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It does create a paradox. Bacteria divide or reproduce very fast yet changed less than apes who reproduced much much less. The paradox continues, the bacteria's machinery for assuring exact genetic duplication is primitive and should make more mistakes compared to apes, yet apes are able to evolve faster. It appears to be an exception that breaks the rules, which is against the law. Therefore is unlawful to discuss.
Your premise is faulty, relying on the assumption that there is some magical 'goal' to evolve faster. Evolution will occur only when different traits are selected for.

Bacteria have found an ecological niche, and perform much better than apes, in those respects. They won't evolve mechanisms to evolve out of that niche, unless the selection pressures dramatically change and there is another niche for them to occupy.

Also, you're premise that bacteria are slow to evolve is also incorrect.

mutation rate is defined as mutations per population per generation. Bacteria have a lower mutation rate, but a much shorter generation time, and evolve new alleles much more quickly than apes.

I comes down to environmental potentials changing the DNA. There is no good place for bacteria to evolve in peace since they are typically surrounded by higher life forms that keeps them in their place. The places where they can live in peace are crappy environments which don't help. There is pressure from the top to keep the bottom. Bacteria turn out to be very useful slaves within the human body performing tasks without having any honor as full genetic citizen. They do rebel at times, but even medicine keeps these low life renegades in their place.

This is a terrible analogy, because like the paragraph before it, you assume that evolution is teleological. Worse, you pretend you are making a moral argument against evolution. As in, evolution is morally wrong, therefore it doesn't exist.

You're understanding of evolution is twisted, and therefore you're arguments against it are flawed.

Bacteria don't 'want' to evolve, neither does any other organism. definitely not in the sense that you're suggesting. Your argument makes as much sense as if I were to say, Newtonian gravitation is wrong because it's not fair that larger mass can pin much smaller masses against it.

This is a false teleological argument, and it demonstrates you basic incompetence in understanding evolutionary theory. At least make an attempt to understand the theory you are attacking.

Their selective advantage is being able to make tons of these to keep ahead of extinction. They plot their revenge and try to thin out of the top to release some of the downward pressure. But apes with excellent genetic duplication and slow reproduction rates are able evolve faster because there is not much in the way of downward pressure.

see above

Edited by ecoli
multiple post merged

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Forget the rainforest... we're finding new bacterial species on our own bodies!

i know , i was just trying to make a point, do you think the bacteria in our bodies, are perhaps evolving? that could be why we find so many new types of bacteria, like all the time.

If I understand you correctly, are you saying that the level of mutations are causing new species to arise on human bodies? Is there any evidence for this process? Also, if we look far enough back in the evolutionary tree, I think we may find a common ancestor cell but not necessarily a bacterium. Interesting points though...

Edited by ecoli
fixed quote tag

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I am relatively new to the Forum so take it easy.

However, despite the life cycle of bacteria (20 minutes per cell division in rich medium), bacteria have stayed bacteria over millions of years. They also would have more mutation due to the sheer rate of cell division than animals so why have they stayed bacteria? Also the same with flies.

this argument is implicitly of the form "if humans evolved from apes, then why are there still apes?" The point is that certain groups of bacteria branched off as they exploited various niches and their ancestors became things like eukaryotes, and some of those branched off into things like yeasts, and some branched off into plants, some into animals, and of the latter, some branched off into various different groups. The same is the case for flies. The emergence of a new group from an old group does not necessarily mean the elimination of the original group. there are four different ways that speciation can occur; allopatric, peripatric, parapatric, and sympatric. if you google these words and look them up you should get a better idea.

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