Are there evolutionary reasons for reproduction?

What do we see in the universe? We see cells reproduce themselves. We see multi-cellular organisms reproduce themselves. We see that this reproduction is not perfect, that in the new being there are changes in the materials that result from these reproductive processes. We see these changes affect the properties of the new being. And we see further changes in materials and properties in the offspring of this new being.Reproduction happens.Evolution does not require reproduction. Reproduction is not a force that drives evolution.Evolution is just a word. It is the word we use to label these processes of life we see around us.We see decent with modification, reproduction with changes. We see the reality of the life systems and their diversity in this world.We needn't justify reproduction as a mechanism. It is a fact. One that must be a part of any explanation of the diversity of life.Edited by AZPaul3, : No reason given.Edited by AZPaul3, : better syntaxEdited by AZPaul3, : No reason given.

Ahh, the question becomes clearer.We do not have a consistent theory of abiogenisis. There are some good hypotheses on several proposed mechanisms but nothing that we have such evidence for that our confidence in any one is high.What we do know to a very great level of confidence is chemistry.We know that each reaction requires a specific level of energy for it to take place. If the environment does not provide a sufficient level of available energy then we put the chemicals in a test tube heat it up (apply a thermodynamic excess) until the reaction occurs.We also know that any reaction that can occur will occur if the materials and energy are available.The beauty of the carbon atom is the 4 valence electrons. It also is not a heavy atom like silicon or sulfur. Therefore, we know carbon is easily reactive yet stable under moderate energy levels. This is why, when we look out into the cosmos, we see very few silicon or sulfur (or any other element) compounds, but we see an abundance (in the 80s by my last look) carbon compounds. Some of these are large molecular structures.This planet exists within a thermodynamic excess. Not strong enough. This planet exists within an enormous thermodynamic excess. This is not just from space onto the surface but from the core outward.By whatever abiogenic process that did occur those billions of years ago a life system arose. As long as the thermodynamic excess continues these life-system processes will continue.

Reproduction causes variation which may lead to enhanced adaptation which may allow an individual to survive long enough to procreate.

No. "Longer existence" is not a factor. "Just long enough to reproduce" is the factor.If the variations that are produced by imperfect reproduction are beneficial then survival may be enhanced to achieve further reproduction. But this not a "goal." If the variations achieve a shorter life span with more prodigious reproduction then this strategy may survive as well.All that is happening is imperfect reproduction of individuals that are fit just enough to survive their environment to reproduce the next imperfect generation. The resultant variations of populations over time is called evolution.Edited by AZPaul3, : No reason given.Edited by AZPaul3, : more corrections

Mechanics. In your example time t1 is less than t2.t1 < t2The 'point' of the sign should point to the lesser of the compared values.Your entire example is predicated on the assumption that evolution has some goal (N). Further, that separate species have the same goal (N). This is incorrect.The processes of evolution do not care what adaptation is achieved, nor care in what time. Frankly, evolution does not care, nor is it geared toward, whether a species survives or not.The mechanism of reproduction is not perfect. Changes are introduced into the offspring. These changes, if beneficial, may lead to a greater ability to reproduce. This may be a greater number of offspring in a shorter lifetime, greater number of offspring over a longer lifetime, any combination or permutation you may care to imagine.Because of the increased reproduction of offspring these changes may become more and more representative of the population. Over time other changes, also beneficial, enter, survive and become attributes of the overall population.After 1000 or 10,000 or 100,000 generations the new population is so changed from the parent population we label this a new species.A species of X cut off on this side of a river may develop different attributes then the same species of X cut off on the other side. Eventually neither side of the river may host X but host separate descendant species Y and Z.Neither Y nor Z will have all the same attributes and neither one was in anyway "driven" to evolve in the direction it achieved. If the attributes of Z are weak and incompatible with the environment then Z may eventually become extinct leaving Y as the sole evolved daughter population of the X species so many generations ago. Z will be gone no matter how much time or how many variations it may or may not achieve.The processes of reproduction with variation do not assure any species' survival. Nor do they assure a population's evolutionary success. The blind random processes of reproduction cut through with the scythe of natural selection may lead a species to extinction, or to a few daughter species or to many daughter species. And each daughter species repeats the process anew.There is no direction to evolution. There is no target.reproduction -> variations ~> survival ~> reproduction -> variations ~> survival ~> ... reproduction -> variations ~> survival ~> reproduction -> variations (speciation) ~> survival ...or maybe:reproduction -> variations ~> survival ~> reproduction -> variations ~> extinction"Longer existence" is NOT a factor. Edited by AZPaul3, : No reason given.Edited by AZPaul3, : No reason given.

The longer life span WILL NOT cause them to become the dominant species outside your idealization. Differential reproduction causes dominance in the real world.In your example, X develops a variation conferring protection from disease but retains the same reproduction rate as all other individuals. X lives longer but is no more productive than any other. In an idealized mathematical case the offspring of X will eventually dominate. However, evolution does not follow any idealized mathematical case. Evolution works in the real world.First there is the case to be made that longer lived individuals of limited reproduction potential sap scarce resources from the species ecological niche thus endangering the species evolutionary future as a whole. Second, any other variation that arises that gives more reproductive success, regardless of longevity, WILL come to domination. These are facts of the world in which we live.Mathematical models are useful if they model the real world. Yours do not appear to do so.

What you missed in this example is that the starting equations had already accurately modeled reality. In true scientific fashion the models made predictions which, sooner or later, could be tested.You also miss those instances, of which there are many, where the equation did not accurately model reality. Again, in true scientific fashion the model made predictions which, sooner or later, were falsified. The equation had to be modified or scrapped.We already know from the facts we have in the real world your attempted model does not accurately reflect reality. Sickle Cell is an excellent example of just what we a talking about.The HbS hemoglobin allele has a single-point mutation from the HbA allele.We receive one hemoglobin allele from mom and one from dad.If one and only one of those alleles is HbS then the person has a great protection from malaria. They live a normal life with no symptoms of Sickle Cell Disease and reproduce as normal.If neither inherited allele is HbS there is no protection from malaria and that portion of the population suffers reduced reproduction potential due to contraction of malaria.If both alleles are HbS then there is protection from malaria but also Sickle Cell Disease which also limits reproductive potential.I'll not go into all the combinations and permutations of the various mating possibilities. What is shown in the HbS trait example is that it was not the trait itself but the reproductive differential conveyed by the trait that makes the HbS allele remain in those affected populations. Indeed it can and has been shown so. No, MrQ, this is not a misnomer, but a lack of understanding (or appreciation) of the facts. No, MrQ. The key factor, indeed the only factor, is the reproductive differential that causes the entire suite of traits we know from an individual's genome to grow or decrease in a population through natural selection.Edited by AZPaul3, : No reason given.Edited by AZPaul3, : correctionEdited by AZPaul3, : another correction

You have totally miss the Sickle Cell example.There are three (3) populations:1) Those with 2 HbA alleles.
2) Those with 1 HbA and 1 HbS allele.
3) Those with 2 HbS alleles. Wiki is a great resource for general knowledge. They cannot, however, give all the details that form that general knowledge in their pages.Let's go to the old standby example of the Peacock with its display of plumage.The lesser displayed Cocks have less reproductive success. Not because of any lesser lifetime or early death but solely due to the sexual selection (a form of Natural Selection) by the Peahen. In fact the Cock with greater plumage is at a survival disadvantage. But, the greater displayed Cock has a reproductive advantage.Over time the grandiose plumage will dominate the population over the lesser plumage because the reproductive differential favors the greater display over longer survival.The Wiki story of the slightly faster rabbit is a good one since it is easy to understand and helps convey the central theme to those wanting a general knowledge. But, do not continue to mistake survival length as the only, or major, venue for evolution.Death may or may not confer a reproductive advantage. It depends on whether death comes before or after reproductive age. Other traits may or may not convey reproductive advantage without impacting lifespan. Greater fecundity at an early age out performs lesser fecundity over a longer life.Lifespan may have an impact but is not the key. Reproductive differential, by whatever means it is achieved, is the key. Edited by AZPaul3, : correction

Yes, of course. But your insistence that:

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Therefore both reproduction and variations are working together to achieve only and one only final goal of longer existence of each species.

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Is quite wrong. There already is a name and it is already complete. It covers not almost all but in fact all scenarios. It is called "differential reproduction." This mechanism, however it is achieved (your death scenarios, sexual selection, any and all other natural selections), is the ultimate key to species diversity and the pace of speciation.That is a broad statement and the details of the various mechanisms are complex, but until you appreciate this one over arching principle the details will mean nothing."Longer existence" for a species means nothing for evolution compared to the reproductive differential that causes diversity, speciation and extinction.Edited by AZPaul3, : No reason given.Edited by AZPaul3, : Added concept.

I hope you're not serious.Longevity, or the lack thereof, may or may not lead to greater fecundity.This is what I said, yes?This means that fecundity (reproductive differential) may or may not be impacted by longevity (your death scenarios).Your death scenarios only fit as they impact the reproductive differential.The point that I emphasize is that factors other than longevity affect fecundity, sometimes to a greater degree. It is the reproductive differential that impacts Evolution. Thus longevity of the species is not a "goal" of evolution.