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Can the evolution of symbionts lead to greater biological complexity?

In summary, the evolution of symbionts can drive greater biological complexity by promoting cooperative relationships between different organisms. This symbiotic interaction can lead to the development of new traits and functions, enhance adaptability, and foster innovation in metabolic pathways. Over time, these relationships can contribute to the emergence of novel biological systems, ultimately increasing the diversity and complexity of life forms.
  • #1
Another God
Hows this for an idea that struck me one day?OK, most 'bugs' that we get are bacteria that release toxins which react badly with us. There are many more bacteria which live inside us and don't release these toxins, so we don't notice them. It would therefore seem that these non harmful bacteria are actualy better evolved than the harmful ones. They are better evolved because the harmful ones cauld cause their host to die. This would result in their own death. The non harmful ones don't do anything wrong, so their host is more likely to continue living, and so give them a good steady home for a long time to come.A better relationship, would be where the bacteria actually helped its host. By doing so, it would actually help its host survive, ensuring it had a more succesful home, and improving its chances of its own survival.A good example of this sort of Symbiosis in nature would be termites, Cows, and Koalas. Each of these animals eats Callulose rich plants as their primary food source, but not one of them can digest cellulose. How does it get nutrition? The bacteria living in its guts eats the cellulose, breaking it down for the animal to get the nutrients from the left over bits. That way the bacteria gets food delivered to their doorstep, and the animal gets a food source which is in high abundance, because most other animals can't digest it.Now, here's the next step which is the idea in question. How often, if ever, in the past do you think that the DNA of a Symbiont has been incorporated into the DNA of its host? Has this concept played any sort of influential role in the evolution of complex internal organs? Maybe our intestines were once some sort of tape worm, long since incorporated into our DNA...?(Koalas aren't born with these bacteria in their gut. When they are babies, they eat the faeces of their parents, and take in the bacteria that way. Nice huh? I am not sure about cows and termites though.)I wonder if Koalas could live without their little cellulose digesting symbionts...??? If my theory holds any water, I wonder why they haven't been incorporated into the Koala DNA yet? How long does it take if it does happen?From a Natural selection stand point, obviously a koala which is born with such an attribute would have an advantage over one which needs to find a source of bacteria...yeah? Selection pressure that way?How long do you want to live?Home to Immortals
 
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  • #2
Just a couple of points. Mitochondria, dispite a symbiotic relationship spanning our (vertebrates) history, havent given over thier DNA. Mothers pass them along in milk, which may be one reason for the success of mammals ('inherited' bacterial symbiotes, which the social insects have also happened upon). Probabally happens quite often with viruses (I suspect the herpes virus will become increasingly asymptomatic til it's become endogenous).But it did happen with plants and cholorophyll. And the first multicellular forms. How?Oh, wait . . . hold on, I'll think of something cute . . .-Memeivorrhea dyscoursus-
 
  • #3
The first complication which I can already see is 'Where is it incorporated into the DNA?' and 'How accurately placed in the DNA does a genotype have to be, to get the desired results?'So, in the case of the bacteria in the gut, could the whole bacteria DNA be incorporated as a new Chromosome? Would that spit out bacteria along with a koala? Would the bacteria be in the koalas stomach, or would they be floating in the womb around the koala? Or would they be stuck in vital organs throughout the poor koala?Then, maybe the gene which gives the bacteria the necessary chemical to break down cellulose could be incorporated directly. Skip the middle man bacteria, and get the single gene that is important... Does this gene have to fit into the koalas genome in a specific place?--> OK, this leads to another more imporant genetics question, which I believe isn't really well understood yet : What regulates gene expression.Maybe the gene can be placed anywhere on the genome, but it needs the right gene expression sequence/chemicals/code whatever to activate it in the right place at the right time.... This could be complicated, and is seeming more and more like Macroevolution all the time.Even so, this idea could explain the numerous Chromosomes in diffferent organisms, and it does also meld well with the Prokaryote turning into Eukaryotic bacteria idea....How long do you want to live?Home to Immortals
 
  • #4
quote:Originally posted by picklehead:Mothers pass them along in milk, which may be one reason for the success of mammalsIn their milk? Did u hear that directly, because it's not what I have always thought. I haven't heard directly otherwise, but it makes more sense that the mother passes the mitochondria to their children because it is the mother which provides the cellular constituents for reproduction, while the father only provides DNA. Mitochondria are part of a cell....cell comes from the mother, therefore mitochondria comes from the mother.I think this idea really occured to me because of things like mitochondria too, so thats a good observation. Mitochondria is very similar to simple prokaryotic bacteria. It seems that Eukaryotic bacteria are just a collection of a few specialised Prokaryotes, working together.My idea is really the extension of that... Can it also work on the organism level? If it works with cells, can organisms incorporate smaller organisms?And the comment about the tape worm being our intestines....I'm semi serious. I doubt that that may be the actual case, but I do wonder if such a thing could maybe happen? Of course, humans directly didn't incorporate it, because millions of mammals came before us which had intestines....but when did intestines evolve? Evolutionists always cop the 'What good is half an eye' argument etc... maybe some body parts didn't go through slow grow procedures. Instead the body parts just altered their functions a bit from being a parasite, to being a symbiote.....?(I'm still very skeptical of my own words...just playing with ideas.)How long do you want to live?Home to Immortals
 
  • #5
I think the digestive tract was actually one of the first systems aquired by multicellular living things, in the group collectively called Stomata (?), meaning thier body cavities are formed by internally developed foldings under the notochord, and the organs themselves develope from the folded portions. I think. Could be wrong though.Oh, wait . . . hold on, I'll think of something cute . . .-Memeivorrhea dyscoursus-
 
  • #6
It seems like most of the Gene incorporating took place long ago in history. Probably because with two similar organisms, with similar encoding and decoding mechanisms for DNA, if one 'ate' the others DNA, it would gain the others' abilities. But if we ate a bacteria's dna at this point we wouldn't be able to use the genes properly.Aren't the protiens and methodolgy we use to decode DNA different enough from a bacteria to render there genes mostly useless to us?And even if they weren't wouldn't a wrong placement just result in as best nothing, or at worse a new inheritable disease?
 
  • #7
AnotherGod:quote:In their milk? Did u hear that directly, because it's not what I have always thought.Oops, my bad. I was thinking of gut bacteria. I think mothers pass thier mitochondria through the placenta . . . but I should prolly check this time, no?Oh, wait . . . hold on, I'll think of something cute . . .-Memeivorrhea dyscoursus-
 
  • #8
I seem to recall something about an experiment involving flat worms. They ran a worm through a simple maze. Once it had memorized it they ground it up, fed it to a worm that had never been in the maze. Apparently the new worm remembered the path. Something to do with RNA. Long time ago and a short popularized article.
 
  • #9
quote:Originally posted by picklehead:Oops, my bad. I was thinking of gut bacteria. I think mothers pass thier mitochondria through the placenta . . . but I should prolly check this time, no?Even still, I feel quite sure that the Mitochondria come from the mother, simply because the mother is the one that provides the cellular constituents, and mitochondria is a cellular thing. The mother only needs to provide one in the begining, and then upon each cellular division, more are made. The mother doesn't 'feed' mitochondria to the baby or anything like that.How long do you want to live?Home to Immortals
 
  • #10
quote:Originally posted by kleinjahr:I seem to recall something about an experiment involving flat worms. They ran a worm through a simple maze. Once it had memorized it they ground it up, fed it to a worm that had never been in the maze. Apparently the new worm remembered the path. Something to do with RNA. Long time ago and a short popularized article.Sounds dodgy. I guess I'd have to see the article for myself.How long do you want to live?Home to Immortals
 
  • #11
quote:Originally posted by Another God:Even still, I feel quite sure that the Mitochondria come from the mother, simply because the mother is the one that provides the cellular constituents, and mitochondria is a cellular thing. The mother only needs to provide one in the begining, and then upon each cellular division, more are made. The mother doesn't 'feed' mitochondria to the baby or anything like that.How long do you want to live?Home to ImmortalsThat right. I saw a discovery channel documentary recently about a hypothetical eve. Basically they used mitochondrial DNA to trace back to a first mother of the human race.That Flatworm thing is probably crap. I never heard of any known creature with a genetic memory. RNA is just a piece of uncoiled single strand DNA sort of thing.The idea of symbiotic bacteria is one that appeals to me. Anyone read the Andronema Strain? That microbe evolved to become harmless, as that was advantageous to survival. To think about it, a disease that kills its host would always be unsuccess, so in a few million years time all of our currnt microbe may evolve to become beneficial.I think I read an article some time ago of interspecials bacterial 'rape', where bacteria aparently had exchanged genetic material with a host cell.
 
  • #12
Kleinjahr:quote:I seem to recall something about an experiment involving flat worms. They ran a worm through a simple maze. Once it had memorized it they ground it up, fed it to a worm that had never been in the maze.Rupert Sheldrake, A New Science of Life. Morphogenic fields shape all living things. Field reacts to something a certain way, voila, evolution. Idea can be extended to crossword puzzles and attempts to solve them will be easier in the afternoon/evening when the puzzles field is more 'filled in' by other 'rats'.Oh, wait . . . hold on, I'll think of something cute . . .-Memeivorrhea dyscoursus-
 
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