|
Register | Sign In |
|
QuickSearch
EvC Forum active members: 63 (9162 total) |
| |
popoi | |
Total: 916,387 Year: 3,644/9,624 Month: 515/974 Week: 128/276 Day: 2/23 Hour: 0/0 |
Thread ▼ Details |
|
Thread Info
|
|
|
Author | Topic: Are there evolutionary reasons for reproduction? | |||||||||||||||||||||||||||||||||||||||
Jazzns Member (Idle past 3932 days) Posts: 2657 From: A Better America Joined: |
Forgive me when I say I haven't read much of this thread. I saw the title awhile back and read the first few posts and it hurt my brain too much to think about how to rationally respond to this.
I occasionally check in on the site and noticed that this thread has stayed alive for awhile and it bothered me that I couldn't think of a witty analogy for why asking the question in the OP is so asinine. So I thought of the one in my title. Are there any others? Are there financial reasons for working?Are there health reasons for eating? What other back-assward comparisons can you think of? If a nation expects to be ignorant and free, in a state of civilization, it expects what never was and never will be. --Thomas Jefferson
|
|||||||||||||||||||||||||||||||||||||||
Taq Member Posts: 10033 Joined: Member Rating: 5.3 |
What other back-assward comparisons can you think of? Are there mucosal reasons for picking your nose? Are there rectal reasons for having your head up your ass? Are there ninja stealth reasons for being so dim?
|
|||||||||||||||||||||||||||||||||||||||
Modulous Member Posts: 7801 From: Manchester, UK Joined:
|
Just in case the other attempts didn't sink in:
At some given point in history, organisms must have made a switch to male/female reproduction. Some organisms yes, not all.
Since each sex would have needed to evolve at the same time Imagine a group of organisms that each ejects 10 seeds measuring 1mm each once per year into a calm area of water. Those seeds combine with each other, more or less by chance, and that is germination with sex. You seem to think this is a perfectly fine situation, yes? Now imagine one organism that came along that produced 1000 seeds measuring 0.0001mm each once per year into said water. One might see that such an organism might have an advantage: They get lots more chances of germination. 100 times more chances in fact. But there is a slight disadvantage: By stripping down the seed, it means that small seeds cannot germinate with other small seeds and rely on all the mechanics in the big seeds to do the work. Agree? So 'small' needs to germinate 'large'. Yes? We have two 'types' but only one of them recently evolved, the other evolved at a different time - we have the original and the evolved? Do you agree that a large seed didn't have to evolve at the same time as the small seed? That the large seed was the original and is only called large relative to the new smaller seed? Do you agree that even though the small seed needs the large seed that doesn't mean the two had to evolve at the same time since the large doesn't necessarily need the small seed (at least initially)?
this seems like a roadblock on the evolutionary highway It seems like a roadblock until you dig a little deeper and you realize that it isn't actually a problem. The stumbling block I think you've encountered in your head might be that female gametes now often require male gametes. But the state of affairs you are used to is not necessarily the state of affairs originally. Think about it like this: After a while the watery environment we described is suddenly filled with lots of 'spare' male gametes that never fertilize. So the female gametes may begin to specialise in capturing the male gametes which may be a better strategy than being ok at both female-female fertilization and male-female. It is almost a biological law that becoming more specialised at one thing makes you less good at other things (it is the principle upon which some vaccinations are made). So it isn't a surprise to learn that many eggs are now so specialized in sperm fertilization techniques that they are very poor at female-female fertilization (although in cases where it is still in principle possible, it occasionally still occurs). Many insect eggs will hatch as one sex unless they are specifically fertilized.
As I said before, I have no issues with asexual reproduction, or hermaphroditic reproduction, as these to not REQUIRE the opposite sex for reproduction. My issue is, and always has been, with male/female reproduction. It is a necessary logic that if males evolve - the thing that isn't male is female. So, even though males may require females to reproduction - they are already in the population. Any mutation which created something that was unable to reproduce with anything around it would obviously die without reproducing and that's no way to evolve a new trait - you are quite right in that. But a mutation which changes the way one goes about reproducing with the things that are commonly around may be successful. And smaller more plentiful gametes is one such thing one can do and biologists call things that use the small plentiful gamete strategy: Male. Those that don't...are called female. The population evolved as female, and males came along to take advantage of that resource. That shouldn't be controversial - the only question is, how did that happen. And that's a different question than the one at hand. Edited by Modulous, : now with 100% more words!
|
|||||||||||||||||||||||||||||||||||||||
Phage0070 Inactive Member |
Jazzns writes: What other back-assward comparisons can you think of? If nobody produces life-sized bobble-head dolls of Luke Perry, why don't we see them everywhere?
|
|||||||||||||||||||||||||||||||||||||||
dennis780 Member (Idle past 4797 days) Posts: 288 From: Alberta Joined: |
You will have to excuse my short reply, I'm respondig on my iPhone. I agree that the new smaller seeds would be related to the previous bigger seeds. Although I'm unsure what organism you are talking about. This does not address the question of male/female reproduction.
What you are refering to sounds like either germination, or asexual reproduction, in which the opposite sex plays no part in the reproductive process. Pointing out that fertilization of eggs is the only way an organism only futhurs my point that for both sexes of a species to exist, both sexes are required. Now later in your post you refer to a biological law that species become specialized to increase their ability to survive. What you are refering to is adaptation, which is the ability for an organism to change to better Suit it's environment. Evolution is a series of random mutations that over time become useful (or microevolution, whichever you prefer). Macroevolution is based on pure random mutation. I have to go, my youngest is starting to cry. I will post again to address your Other points. I apologize. If a hypothetical organism laid any number of eggs (the amount is irrelevant), without a suitable opposite sex, the eggs would die. This could continue until the organism capable of male/female reproduction would no longer be fertile, or die.
|
|||||||||||||||||||||||||||||||||||||||
Modulous Member Posts: 7801 From: Manchester, UK Joined:
|
I agree that the new smaller seeds would be related to the previous bigger seeds. Although I'm unsure what organism you are talking about. No specific organism - lets call it hypothetia {a hypothetical organism}.
This does not address the question of male/female reproduction. It directly addresses it. When you have time, re-read my post. Hypothetia that produce smaller seeds are called 'male'. The original organisms that produce the larger seeds are called 'female'. We have just devised a way for male and female things to come into being at the same time, without the need for both of them to simultaneously evolve.
What you are refering to sounds like either germination, or asexual reproduction, in which the opposite sex plays no part in the reproductive process. That is the primal state of the hypothetia population. It is from this state we think about how to evolve sex and sex differentiation.
Pointing out that fertilization of eggs is the only way an organism only futhurs my point that for both sexes of a species to exist, both sexes are required. Except I specifically pointed out that both sexes are not required in hypothetia. The females can reproduce without males since that is how they started in their primal state. The only new thing that was introduced was that males existed that NEED females. The females did not start off needing the males.
Now later in your post you refer to a biological law that species become specialized to increase their ability to survive. What you are refering to is adaptation, which is the ability for an organism to change to better Suit it's environment. Actually I was being even more specific than that. I was pointing out that the more specialised an organism becomes to a specific environment, the worse it does in other environments.
If a hypothetical organism laid any number of eggs (the amount is irrelevant), without a suitable opposite sex, the eggs would die. Aphids beg to differ (though they don't generally don't bother actually laying the eggs, and they incubate them internally). If you ever get the youngest pacified, consider reading about Parthenogenesis quote: Added by edit: Don't take my word for it, go look up the evolution of anisogamy yourself:
Cooperation and the evolution of anisogamy Gametic conflict versus contact in the evolution of anisogamy The quick and the dead? Sperm competition and sexual conflict in sea. Selection for high gamete encounter rates explains the evolution of anisogamy using plausible assumptions about size relationships of swimming speed and duration. Naturally, reality is much messier than hypothetia - but if you can't get your head around her...you won't have a chance with the real deal. Edited by Modulous, : No reason given. Edited by Modulous, : No reason given.
|
|||||||||||||||||||||||||||||||||||||||
Asking Junior Member (Idle past 5058 days) Posts: 19 Joined: |
You might want to read Nick Lanes book The Ten Greatest Inventions of Evolution as that covers sex. The first answer is that life possibly originated through the differential survival of replicating molucules and as evolution has no forsight its irrelevent if the resulting competition between replicating molecules and later cadres of replcating molecules has no purpose.
The second aspect is that recombination during gamete production provides an oppurtunity for genes that reduce fitness to be removed and genes that enchance fitness be conserved. If an organism has several offspring then there is a good chance that in some of them the majority of beneficial genes will end up in one of them and a bunch of rubbish ones end up in another. The one with the good genes has a greater chance of reproducing whilst the one with the poor genes is less likely to reproduce. This is also an important mechanism for spreading beneficial genes through a population. Some organisms do breed asexually but tend not to do very well in the long run if they do not resort to sexual reproduction at some point or have some other means of altering their genetic material. Edited by Asking, : No reason given.
|
|||||||||||||||||||||||||||||||||||||||
dennis780 Member (Idle past 4797 days) Posts: 288 From: Alberta Joined: |
"Some organisms do breed asexually but tend not to do very well in the long run if they do not resort to sexual reproduction at some point or have some other means of altering their genetic material."
any examples of any animal adding to it's genetic code? (excluding pre existing information). Actually, the most abundant organisms in the world reproduce asexually. Almost all bacteria reproduce this way. "life possibly originated through the differential survival of replicating molucules" but since we are attempting to deal with data, not theories, I would like some sort of reconstructed experiment somewhere supporting your theory.
|
|||||||||||||||||||||||||||||||||||||||
Asking Junior Member (Idle past 5058 days) Posts: 19 Joined: |
any examples of any animal adding to it's genetic code? (excluding pre existing information). Evolution operates through the modification of existing genetic material, not the modification of genetic material which appears out out thin air. Therefore the condition that I exclude genetic material originating from pre-existing genetic material means that any answer I give has no bearing on evolution. As far as I know genetic material doesn't just appear out of nothing as the available evidence points to it being the product of pre-existing genetic material. Anyway the evidence for where the additional genetic material originates from. Gene duplication - http://171.66.122.45/content/9/7/629.full (Just one paper but there are countless more available if you search on google). The long and short of it is that the genes coding for Opsin have been duplicated and mutations alter the frequency of light they react to. This is actually a well researched subject and its been determined experimentally which specific mutations are required to alter the frequency of light they reach too. This is how we evolved tri-chromatic vision. Just google gene duplication as this will give more information about its relevence to other aspects of biology beyond sight. Evolution works through modification of what exists and gene duplication is a valuable source of genetic material to modify for another use. Polypoidy - (Polyploidy - Wikipedia) Most common in plants although there is a shrew which does this too and has an impressive number of chromosomes. Basically its the doubling up of the normal amount of genetic material in an individual organism which also has the side-effect of reproductively isolating it from its parent population and therefore leading to speciation.
Actually, the most abundant organisms in the world reproduce asexually. Almost all bacteria reproduce this way As I said unless they have some other means of altering their genetic material which is done via lateral gene transfer and mutations. Without this bacteria wouldn't be as resiliant as they are and doctors would have a much easier time stamping out bacterial infections. There are some animals that reproduce asexually but this is not an ideal method because 1) Benefitial mutations are restricted to a single lineage and cannot be rapidly distributed within a population, 2) Detrimental mutations can't be weeded out of a lineage as they can be with sexual reproduction, 3) as most mutations are either neutral or detrimental the net effect of asexual reproduction is a reduction in fitness.
but since we are attempting to deal with data, not theories, I would like some sort of reconstructed experiment somewhere supporting your theory. I first became aware of this after reading Nick Lanes book and have no looked into it again recenlty but here is a publication from 2007 looking into the origins of life at hydrothermal vents (On the origin of biochemistry at an alkaline hydrothermal vent - PMC). I believe that this was going to be tested experimental but after a quick look around I can't find anything stating explicitely some results from this (I'm no chemist so I may have missed something). When it comes to ambiogenesis though without being able to go back in time and see whats happened we'll never be able to say what exactly happened, only come up with scientific theories supported by experimental evidence as you rightfully expected. ------- Returning to the original point have I answered the query as to what evolutionary reasons there are for sexual reproduction? Edited by Asking, : No reason given. Edited by Asking, : Bringing back to original question. Edited by Asking, : No reason given. Edited by Asking, : No reason given. Edited by Asking, : No reason given. Edited by Asking, : Alteration of original paragraph Edited by Asking, : Added quotations Edited by Asking, : No reason given. Edited by Asking, : No reason given. Edited by Asking, : No reason given. Edited by Asking, : Clarifying something Edited by Asking, : No reason given.
|
|||||||||||||||||||||||||||||||||||||||
Fiver Junior Member (Idle past 4984 days) Posts: 26 From: Provo, UT Joined: |
To reply simply and briefly to the original point:
"Survival of the Fittest" works on species, divisions, and alleles... not individuals. Since reproduction ensures the extension of the gene pool (and lack of reproduction would guarantee its death), it is clearly the best evolutionary path to be taken by an organism.
|
|||||||||||||||||||||||||||||||||||||||
dennis780 Member (Idle past 4797 days) Posts: 288 From: Alberta Joined: |
"Evolution operates through the modification of existing genetic material"
Wrong, or single celled organisms would have the information required to code for all of any organisms traits and physical features. Evolution requires adding of new information over time. "As far as I know genetic material doesn't just appear out of nothing" I won't argue with you. "available evidence points to it being the product of pre-existing genetic material." Although I'm sure this is a topic for another thread, I'm curious to know what information this is exactly...is there a thread for this? "Gene duplication - http://171.66.122.45/content/9/7/629.full " This has no information on new information, only existing information. Furthurmore, it goes into great deal about cloning. I'm not sure if I mentioned this before, but similarity is also support for design. Since all cars have spark plugs, steering wheels, tires, seats, transmissions, doors, frames, etc., they too were designed. Genetic similarities in ape vision and human vision only shows that they are similar. Not that they are related. Although this is irrelevant to the topic on this thread, I'll reply briefly, since you do not need to discuss the 256 bp similarities to know that human eyes are not related to Apes of any kind. Since Apes have brown eyes, their alleles code for AA (A or a being dominant or recessive traits respectively). Since brown eyes are dominant, and apes are homogenius dominant A, it's not possible for humans to have any recessive colors of eyes, such as blue or green. Even if by random mutation, one member of a primative species (that led to humaniods today) did get a recessive (a), the odds of the offspring recieving that trait is still 0%, as the mate would be AA, and the other would be Aa, leaving only the possibility of AA (50%), or Aa (50%). The offspring (if coded for Aa from the respective mate) would have the same odds, 50/50, but eye colour would still be brown as 2 recessive genes are required (aa). "Benefitial mutations are restricted to a single lineage and cannot be rapidly distributed within a population" I agree completely. "as most mutations are either neutral or detrimental the net effect of asexual reproduction is a reduction in fitness." I agree as well. However, asexual reproduction has it's advantages as well. 1. Asexual organisms do not have to search for a mate, and this leads to greater population growth. 2. Greater populations have greater chances of survival if there is any habitat change (be it preditorial, or environmental), and greater numbers also means out-completing organisms of similar nature for nutrients and water. "origins of life at hydrothermal vents" Read about this years ago. The logical mind refutes this instantly, since incomplete chemical structures travelling from land to the ocean floor sounds like a fairy tale. Even so, supposing this is even plausible, you still do not have DNA or mRNA to allow for reproduction. You also do not have more complex structures such as protiens (that are required for reproduction, orientation, and oxygen distribution). You do not have any usable information (such as DNA), that can be copied, that is stable, and that contains useful information. "Returning to the original point have I answered the query as to what evolutionary reasons there are for sexual reproduction?" I'm not sure why this question is asked. Even I can argue for evolution on this point, that without reproduction, life would cease to exist. I think we're in the wrong thread. Is there one for the topic we are getting into?
|
|||||||||||||||||||||||||||||||||||||||
Huntard Member (Idle past 2315 days) Posts: 2870 From: Limburg, The Netherlands Joined: |
dennis780 writes:
They don't.
Since all cars have spark plugs...
|
|||||||||||||||||||||||||||||||||||||||
Asking Junior Member (Idle past 5058 days) Posts: 19 Joined: |
"Wrong, or single celled organisms would have the information required to code for all of any organisms traits and physical features. Evolution requires adding of new information over time."
Evolution does not require the adding of completely new genetic material over time. It works with existing material and through gene duplication and polypoidy it can provide additional material originating from existing genetic material to work on. If you want another example in addition to humans evolving tricolour vision via gene duplicaiton look up the information regarding the evolution of the component proteins of heamoglobin which relied upon gene duplcation. "Although I'm sure this is a topic for another thread, I'm curious to know what information this is exactly...is there a thread for this?" Look up the stuff I've mentione above and don't expect to be spoonfed everything. "This has no information on new information, only existing information. Furthurmore, it goes into great deal about cloning. I'm not sure if I mentioned this before, but similarity is also support for design. Since all cars have spark plugs, steering wheels, tires, seats, transmissions, doors, frames, etc., they too were designed. Genetic similarities in ape vision and human vision only shows that they are similar. Not that they are related." Its becoming apparant that you don't understand what I'm saying or are just ignoring it. Gene duplication creates more genetic material from existing genetic material upon which evolution can act. I have not said that gene duplication or polypoidy created new information, only that it provides more genetic material for evolution to operate that is sourced from existing material. "I agree as well. However, asexual reproduction has it's advantages as well. 1. Asexual organisms do not have to search for a mate, and this leads to greater population growth. 2. Greater populations have greater chances of survival if there is any habitat change (be it preditorial, or environmental), and greater numbers also means out-completing organisms of similar nature for nutrients and water." Your first point is true but your second point is way of the mark. It doesn't matter if there are a million individuals in a population if they can't evolve quickly enough to keep up with changes in their environment. "Read about this years ago. The logical mind refutes this instantly, since incomplete chemical structures travelling from land to the ocean floor sounds like a fairy tale. Even so, supposing this is even plausible, you still do not have DNA or mRNA to allow for reproduction. You also do not have more complex structures such as protiens (that are required for reproduction, orientation, and oxygen distribution). You do not have any usable information (such as DNA), that can be copied, that is stable, and that contains useful information." There is a much better account of this in Nick Lanes book on evolution and in his account its a combination of hydrothermal chemistry and self-replicating RNA. It doesn't require proteins when RNA can replicate itself. This is also supposed to be the begining of life (Life defined as something capable of multiplication, heredity and variation) and so why would we expect to have all the things in place that would have evolved later on?
|
|||||||||||||||||||||||||||||||||||||||
dennis780 Member (Idle past 4797 days) Posts: 288 From: Alberta Joined: |
"Gene duplication creates more genetic material from existing genetic material upon which evolution can act."
I'm going to assume that you didn't know that almost all organisms today have error checking systems for DNA both before and after recombination. "Your first point is true but your second point is way of the mark. It doesn't matter if there are a million individuals in a population if they can't evolve quickly enough to keep up with changes in their environment." Let me explain this better. Asexual organisms would out-compete organisms that breed male/female, in the case of an earthquake, or flood (just examples). This is because for any organism breeding male/female, a suitable partner is required. Asexual organisms would deal better with this case, since even alone, they can reproduce. "There is a much better account of this in Nick Lanes book on evolution and in his account its a combination of hydrothermal chemistry and self-replicating RNA. It doesn't require proteins when RNA can replicate itself." Your right. But without enzymes, there is no chemical reaction to produce ribonucleic acid, the back bone for DNA and RNA.
|
|||||||||||||||||||||||||||||||||||||||
Wounded King Member Posts: 4149 From: Cincinnati, Ohio, USA Joined: |
I'm going to assume that you didn't know that almost all organisms today have error checking systems for DNA both before and after recombination. Should we also assume that you didn't know such mechanisms are far from perfect and that despite them there is a wealth of hard genetic data showing that genes are continuously being duplicated within the human population (Sharp et al., 2005; Bailey et al., 2008; Zhang et al., 2009). Even between monozygotic twins there are instances of copy number variation (Bruder at al., 2008).
But without enzymes, there is no chemical reaction to produce ribonucleic acid, the back bone for DNA and RNA. This is not really correct, both purines (A,G) and pyrimidines (C,T,U) can be produced from prebiotic precursors without the need for any enzymes, as can ribose. These elements can, in the case of the purines at least subsequently form ribonucleic acids, but these are not stable. There are however a number of alternative chemical routes to RNA production which have yet to be properly explored, for a review of a number of these see Anastasi et al. (2007). So chemical reactions do exist to produce and oligomerise RNA nucleotides, but as yet a fully plausible set of prebiotic conditions which would allow them is not apparent. One paper from last year has shown some success in producing activated pyrimidine ribonucleotides from prebiotic 'feedstock' (Powner et al., 2009). TTFN, WK Edited by Wounded King, : No reason given. Edited by Wounded King, : No reason given. Edited by Wounded King, : Added copy number variation material.
|
|
|
Do Nothing Button
Copyright 2001-2023 by EvC Forum, All Rights Reserved
Version 4.2
Innovative software from Qwixotic © 2024