Are there evolutionary reasons for reproduction?

Hi allI have been studying evolution recently with more attention. There is one question that I couldn't find an answer for. I hope somebody here can enlighten me.The question is in all texts of evolution life correlates to reproduction and reproduction is a key driving force in the evolution process. But nobody actually said why is that the case?! I mean, reproduction is very energy consuming process. Why would a cell is programmed to reproduce itself from evolutionary perspective? Also if you can elaborate on the origins as well. Like if we assume the life came from organic molecules in the earth atmosphere or in a primordial soup, why on earth should a molecule suddenly decide to reproduce or even forced to reproduce? I have read wikipedia about selfish gene. It says Dawkin's claim that a reproducing molecule have an advantage over other molecules. I don't understand where is this coming from. What I think is that whist reproduction can increase the density of the molecule in a solution but also soon the resources will finish and the process ends there. Much like when a fire starts. It extends as far as it has fuel and air to burn and then stops. I don't understand what is the advantage here?!Regards
MrQEdited by MrQ, : Title changedEdited by Admin, : Fix title.

HiSorry about that. I am new here. I changed the topic. I hope it is ok.Regards
MrQ

Thanks for your replay. I understand that evolution may have been started from reproducing molecules. I mentioned that in my second part of the message. But my problem still exist at molecular level. The point is molecules follow physical laws to react with each other. As I gave example like burning. For a example, a spark starts a fire in a jungle and it continues to burn as far as it has fuel and air. Molecular reproduction has no control and once it starts it uses all the material to produce new molecules. This brings no advantage to the environment or the molecule itself. It is like a chain reaction. Also if your point is that the same kind of reproduction later on evolved to more sophisticated reproduction system in single cells, then still problem exists. Reproduction is energy consuming process rather than chain reaction which is like rolling a ball down the hill. Therefore, reproduction it is more like going up the hill. As evolution prove to be very selective and trims any unnecessary energy consumption, then why didn't it stop reproduction? I hope you have understood what I meant. Basically, for everything developed in the evolutionary process there should be an advantage. Like Giraffes developed high legs and neck to use leaves of trees as food as well as escape from predators. But I don't see any advantage in reproduction what so ever. So I don't know why it has been developed in the first place and stayed there in the second place.

Hi Wounded KingThanks for your reply."since there can be no evolution without some sort of self-replicating entity, you are making a whole lot of totally unwarranted assertions."I don't believe this will solve any problem. Everything that happens ultimately needs a reason or preconditions to happen. For example, if somebody asks why big bang happened? and you answer because we are here then you end up in a loop. As reproduction is a requirement for evolution then it should have been around before it otherwise it doesn't make any sense. It will become like chicken and egg problem."The species which adopt your favoured strategy of never reproducing tend to die out very quickly"Death is something else which I haven't touched yet. You could easily reproduce less but have a longer life to keep species going. But there is small point here, less reproduction means less generation and less changes in species as well but certainly it consumes less energy.Regards
MrQ

Hi Jumped Up Chimpanzee"An individual organism that spends no energy on reproduction (e.g. myself!) is not going to produce any offspring. I.E. I will not produce any offspring with the same trait of not spending energy on reproduction."I assume that if what Taq said is true then you are the most intelligent one!I kind of got the idea but it is really counter-intuitive. I mean the precedence of the events is the tricky part. But still reproduction at molecular level is some how mysterious. Chemical reactions go to lower energy. Otherwise they need energy to happen. As they are dumb, they use all the energy to reproduce. This is all fine. But what about variations?I sum up the argument based on my original question. I was looking for reasons(advantages) of reproduction in evolutionary process. Taq mentioned that "Such a species would have less variation within the population". Then the answer to my original question was "variations". It means the evolutionary reason for having reproduction is only to produce variations. But at molecular level we don't have any variations so there is no reason to reproduce. Edited by MrQ, : make it complete

I kind of sum of the whole argument in following diagram. each -> means (existence depends on):reproduction -> having variations -> better adaptation -> live longerI would appreciate if somebody endorses this or comment on it as I want to take it further.

Thanks, then relation between reproduction and variation is different than others. So lets take ~> as "may cause" and change the name of -> to "definitely cause"reproduction -> variations ~> better adaptation ~> live longer ~> better reproductionIt seems to me reproduction's job is to create variations and variation's is to create more reproduction. However all this is limited by the energy consumption. More reproductions, means more energy consumption therefore, some organism develop the habit of living longer instead of reproducing more to extend their species life span. So I am not so sure about the last bit of the diagram. Do species live longer to better reproduce or save energy?

Hi allThanks for all contributions. It is really interesting debate. This type of comments came up several times. I guess my postings had the same fate as "selffish gene" misunderstandings. I totally understand that species or evolution itself doesn't have conciseness and the process goes forward randomly. But as time moves forward, there is a virtual sense of reason and direction enforced by the overall process. Therefore, there is a overall reason behind every step of the evolution and that is what I am interested in. I presented part of it in the diagram and interested in make it more complete. We assume that the randomness of the event can cause some steps against the direction but as time increases the overall direction should stay the same.Catholic Scientist has made good contributions as well. Considering your and his/her remarks I deduct following statement.In evolution "longer existence" is species is important. Organisms takes different strategies to achieve it. Some develop short life span and higher reproduction rate and some longer life span, more intelligence and lower reproduction which also saves energy. Therefore I change my diagram to following:reproduction -> variations ~> better adaptation ~> longer existence(survival)Therefore both reproduction and variations are working together to achieve only and one only final goal of longer existence of each species. Is this better?Edited by MrQ, : survival

I have read this in other biology text. But according to what we discussed, it is not true. The correct sentence would be "Survival should be at minimum long enough to reproduce". Therefore, survivals or longer existence can far surpass the reproduction age but as far as the species in the overall can maintain their existence then it should be fine. This is also true from following facts:Assumption: Evolution process can't foretell the future therefore evolution is not bounded by any time limitLim t-->inf (t is time)
number variations that is needed to reach certain adaptation = N
number of variations/t= Variation rate(v)Then we consider two species x and y, x has got high birth and death rate but enough to survive as v is high in x then probability of reaching to N in time T1 is P.For Y if the probability of reaching N is also P but because variation rate is significantly lower than x then it reach to that level in T2.It is apparent that T1>T2, means that X reaches adaptation faster. But as evolution is not bounded by any time limit, there will be a definite time that Y also reaches the adaptation necessary only and only if it can survive for T2. Therefore, survival to adapt(in digaram these two is shown to be related) is the key factor here not survival to reproduce. Reproduction is just the basic requirement and is not critical factor in the rest of the process as I see it here. But as you can see in the diagram it certainly relates to other factors. Therefore, if reproduction drops to certain level that the survival gets in trouble then that species will be doomed.reproduction -> variations ~> better adaptation ~> longer existence(survival)If anybody have comments on this please mention as I want to take it further.

What I meant by sentence "reproduction is there to create variation" was in long term evolutionary process. Chain reactions happen but they soon use all the resources and the process ends there. The chemical reactions becomes like simple burning a wood, it happens as far as it has the fuel and air and finishes to a dead end. Some reactions are energy dependent. For example like turning water to ice and vise versa. These reaction happen periodically as the source of energy comes and goes. Like for example in day ice gets warm and turns to water and at night freezes. So this process goes on forever but nothing can come out of it in terms of adaptation or evolution. To have evolution you MUST have reproduction and you MUST have variations at the same time unless it doesn't work.

Thanks for your reply. Yes, because I had the assumption that reproduction is a target for evolution. But what I now understood is that it is only a requirement. This misunderstanding I guess comes from some of the terms that biologist use. They usually correlate everything to reproduction as the target which is not correct. The target is "survival of species" and changes in reproduction is only a by product of it.Now if we have settled this bit. There is another problem which I would like to know about. Returning back to my diagram:reproduction -> variations ~> better adaptation ~> longer existence(survival)If longer existence of species(survival) is the target for evolution then how do you differentiate between species considering the variations? I mean there is a contradiction here like two opposing forces. Variations may cause better adaptation which in turn may cause better survival for a specie. But when an organism changes, it is no longer the original species. So in fact what that becomes capable of longer survival is a different type of species. For example a bird develops longer beak to use syrup in flowers as an energy source. The bird before and after this genetic change are in fact two different species as their genetic code is not longer the same. Does anybody know when in biology two species are considered separate?

You need to consider that 'survival' depends on two forces. One is reproduction and the other death. It is logically impossible to find a living specie that its death rate was higher than reproduction for a long time. This is simple math. However, the difference between a single virus and its specie as a group was something I noted earlier as a problem here. We have to somehow differenciate these two and see if really the target is 'survival of species' or 'survival of trait' or even 'survival of a gene'. I still believe 'survival of ....' is a better term. Reproduction doesn't mean anything if death rate is higher. My problem is survival of what? specie or trait or phenotype or a single gene or ... hmm, from this I can surely say that 'survival of specie' is definitely wrong then. Also I know 'survival of individual' is wrong as that single successful individual will die anyway. I guess the right word would be 'survival of trait'. Anybody?Edited by MrQ, : spell

That's was mistake. Thanks for pointing it out. This doesn't make sense at all. I don't know why everybody is so focused on reproduction. I can easily break your theory by saying what if variation didn't change the reproduction at all but dropped the death rate? for example by better resistance against an illness. This will only lengthen the life span of that specie and cause them to be a dominant specie as you pointed out. When you are dominant specie, you consume more resources from the environment and gradually the other non-dominant species become extinct. Pay attention that in this whole entire process the reproduction stays the same with no changes at all. So reproduction can't be the target. I totally understand. You see there are several abstraction layers here which seems to be confused. At lower level you are absolutely right. But at higher level if you consider probabilities and long time span then you will find that the process is not blind at all and even doesn't look blind! We see a proper target and vivid forces work together to get to that target. This target or targets might be there by chance but that doesn't make them non-existant.I give you an example to understand it deeply. In quantum world there is no way that you can say for example an electron is located where at a specific time around in hydrogen atom. It is all probabilistic and that individual electron blindly and randomly revolves around the core and stay in proximity by the forces evolved. But this whole concept doesn't mean that we can't draw a probability graph of the area that single electron stays most of its time. You can't say because the process is random and blind, we can't find any area. In fact calculating this orbitals is a key concept in quantum theory and whole chemistry is based on it. Even you can predict what an atom will do in a chemical reaction based on these orbitals without knowing what happens at lower abstraction layer. That's the beauty of probability theory.

I don't know if you have followed all the thread. I extracted these forces based on people's comments and did logical analysis of those. I have said that there is no doubt reproduction is a key force and a requirement in evolution process. That is very obvious and I don't believe it needs any argument to prove that. But mathematically speaking I am looking for primary and secondary parameters. Let me give you an example. For example we have following function:f(x)= y = x^2 -1What do you normally do if you want to draw this function is to put some x in and calculate the y and draw it. But that's not the only way. Here x is primary parameter and y is secondary. If you want to find out what x give you y=4 then you need to solve the equation based on that. Solving an equation is simply to change it in a way that its primary and secondary parameters change their place. There is slight difference between primary and secondary parameters and that is secondary parameter is calculated from primary and the primary is the main variable which changes. Although in mathematics, there is not huge difference but in real world it can mean a lot. For example time in physics is primary parameter in many formulas. There is a simple fact that you can't do that much with time as it moves forward and makes things change.Now in evolution assume that there are many primary forces as you said like genetics(G), reproduction(R), death rate(D),..... all these come in an equation like this:Y= G(t)+R(t)-D(t)+...Ultimately as you can see all of these parameters relate to each other and they affect each other. But when we say we have competition in species then we have to see what is ultimately is changing? If we call Y survival, is it that the case that all these forces are working to make Max(Y)? It doesn't make sense to put reproduction here as it is already there as primary parameter.Another evolutionary example is to assume that we have two slightly different species of bacteria in one petri dish. They both eat the same food and in fact they are very similar. Also assume the only thing that is different between them is the color and the petri dish is under sunlight. The light color specie gets affected by sunlight and have slightly higher death rate. But their reproduction rate is unaffected. Mean that they reproduce with the same rate as the other specie. After sometime, you will notice that the dark color specie will be dominant in the petry dish as they die slower so they become dominant. So if you are talking about differential reproduction then you need to talk about differential death as well. What I did was that I sum up all these parameters involved and called it survival. You can call it dominance if you like it better. Basically this is so straight forward that doesn't even need argument. The whole thing I am saying is that all these forces are working to maximize dominance of an specie and that is the main target. Reproduction is just one parameter involved in this and you can increase it or decrease it. As far as dominance doesn't change or increases still that specie will be a winner. I hope that I made myself clear! Edited by MrQ, : spellEdited by MrQ, : No reason given.

Agreed. So survival or dominance is also metaphorical parameter that ultimately created by the system. I don't see anything wrong in naming things as everything in science is like that! Do you really really believe electrons move in orbitals?! Also there is no such a thing as perimeter of an geometric object. Perimeter in real world is just an illusion as well as the whole euclidean geometry which we use everyday.