A complex system, while certainly effective at competing, still has the higher cost of complexity. It is not apparent to me why complexity is maintained.
It is maintained because those costs can be met.
__________________ We can allow satellites, planets, suns, universe, nay whole systems of universes, to be governed by laws, but the smallest insect, we wish to be created at once by special act.
This explains why some complexity still exists. Not why complexity does not evolve into simple forms. Why no "cycles" in the graph of life. Why don't we see any lineage that flows from low genetic complexity to higher back to lower.
This explains why some complexity still exists. Not why complexity does not evolve into simple forms. Why no "cycles" in the graph of life. Why don't we see any lineage that flows from low genetic complexity to higher back to lower.
Define "complexity". Many istances of character reversal and vestigiality have been noted in evolution. Is this what you are referring to?
__________________ We can allow satellites, planets, suns, universe, nay whole systems of universes, to be governed by laws, but the smallest insect, we wish to be created at once by special act.
I assume you are suggesting possible explanations for why devolution (as I described it) does not occur, but I fail to see the explanatory power in these subjects with regard to my question. The fact that simpler systems can compete is clearly evident by the success of simpler systems. A complex system, while certainly effective at competing, still has the higher cost of complexity. It is not apparent to me why complexity is maintained.
I don't know if this question fits or not in this topic, but I wonder if part of the answer lies in how much of the genome effectively impacts the organism. We have a much larger genome than bacteria, but bacteria have much less non-coding DNA. Perhaps if we looked only at the part of the mammalian genome that is expressed, it wouldn't be that much more than what you find in prokaryotes.
Dawkins suggests in The Selfish Gene that surplus DNA may be a sort of genetic parasite--"a harmless, but useless passenger, hitching a ride."
__________________ The high, the low, all of creation God gives to humankind to use. If this privilege is misused, God's Justice permits creation to punish humanity~~ Hildegard of Bingen cited in, Earth Prayers from around the World
I don't know if this question fits or not in this topic, but I wonder if part of the answer lies in how much of the genome effectively impacts the organism. We have a much larger genome than bacteria, but bacteria have much less non-coding DNA. Perhaps if we looked only at the part of the mammalian genome that is expressed, it wouldn't be that much more than what you find in prokaryotes.
Dawkins suggests in The Selfish Gene that surplus DNA may be a sort of genetic parasite--"a harmless, but useless passenger, hitching a ride."
There are real gene number differences, also the whole idea of "junk DNA" is being seriously questioned right now. The current thinking is that while there is undoubtedly DNA sequences that do nothing but take up space the percentage that falls in to this category is far smaller then once thought.
This does not address the core issue of why there is no large reduction in base pair values in any species over great periods of time.
Is there a reason for it to be? Remember, there must be selective pressure on something for changes in it to be passed along.
For argument's sake, let's say 15% of our example animal is actual, honest to goodness, not coding, can be lost with no harm, truly junk DNA. The ones that do take up space. Currently noncoding is a lot more, but 15% is actually junk. What pressure would make this animal get rid of 15% of its DNA? Where would the mutation to stop coding DNA come from? How would it get only that 15% or so gone but keep the rest that is necessary? Etcetera etcetera etcetera. Remember, changes don't just randomly happen, they happen IN the DNA, as mutations or other methods. So there would have to be a change IN the DNA to make some of the DNA stop being coded, but only parts that are ACTUALLY junk, and it would have to confer enough of an advantage in the environment to be worth keeping. Since such a change hasn't arisen, we wouldn't see what you wonder about.
Metherion
__________________ Oh, for the love of Pete!
PETE HAS NOTHING TO DO WITH THIS!!!!
And, because I won't write anything I'm not willing to attach my name to...
Is there a reason for it to be? Remember, there must be selective pressure on something for changes in it to be passed along.
For argument's sake, let's say 15% of our example animal is actual, honest to goodness, not coding, can be lost with no harm, truly junk DNA. The ones that do take up space. Currently noncoding is a lot more, but 15% is actually junk. What pressure would make this animal get rid of 15% of its DNA? Where would the mutation to stop coding DNA come from? How would it get only that 15% or so gone but keep the rest that is necessary? Etcetera etcetera etcetera. Remember, changes don't just randomly happen, they happen IN the DNA, as mutations or other methods. So there would have to be a change IN the DNA to make some of the DNA stop being coded, but only parts that are ACTUALLY junk, and it would have to confer enough of an advantage in the environment to be worth keeping. Since such a change hasn't arisen, we wouldn't see what you wonder about.
Good point, but you almost seem to be proposing a law that there will never be selective pressure to reduce "junk" DNA. This does not seem plausible to me. The advantage of not having junk DNA would be an energy advantage at the very least. The energy used in mitosis and transcripting useless DNA could be significant. Even if we are in an energy rich environment it still means more energy could be used in valuable biomass as opposed to useless biomass.
Good point, but you almost seem to be proposing a law that there will never be selective pressure to reduce "junk" DNA. This does not seem plausible to me. The advantage of not having junk DNA would be an energy advantage at the very least. The energy used in mitosis and transcripting useless DNA could be significant. Even if we are in an energy rich environment it still means more energy could be used in valuable biomass as opposed to useless biomass.
I'm not trying to formulate a law saying that it can't happen. Yes, it could very well be an advantage, a huge advantage! But it would need a huge complicated system that would need to do many things:
1. Determine some way to sort useful and useless dna.
2. Copy only the useful stuff.
3. Discard the useless stuff.
4. Oh wait. All the useless stuff is gone. This system has no more use.
It would be pretty much a one shot thing. After it gets used once, there is no more need for it for... well, long enough for more true junk to get built up. And in the meantime this system would basically BECOME junk in and of itself, right?
The thing is... generation to generation change is the name of the game. We don't tend to see a lot (if any, I know of exactly zero) big one-shot changes that occurred in one organism and spread to the rest to be used once and then kind of 'fall off'. Evolution doesn't really work that way as far as I know.
So yes. Cutting out a bit less than 15% of the mass and energy species X would need to survive would be very useful. But a system like that wouldn't really arise via any known means to be used for one shot. It would be formed most likely in successive steps, since it would be quite complicated, have to have some way of determining useful and useless remnants, which would as far as we know require intelligence and a catalog/map of the entire species X genome, as well as a way to discard the stuff, and have each of these steps either do something useful to the organism (which they really wouldn't as described) or be part of a totally different system that changed function later. And since they would ALL have to be in and/or around the DNA reproduction genes it would seem really unlikely they would all arise.
Yes, the end result would be beneficial. But evolution is blind, it doesn't seem the end result, but each step. And since the steps would involve a lot of useless stuff being set up till near the end... it wouldn't happen. As far as I know. But a cellular evolutionary biologist would know more >.<
Metherion
__________________ Oh, for the love of Pete!
PETE HAS NOTHING TO DO WITH THIS!!!!
And, because I won't write anything I'm not willing to attach my name to...
Linear Mode
