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Author | Topic: Are there evolutionary reasons for reproduction? | |||||||||||||||||||||||||||||||||||||||
MrQ Member (Idle past 5052 days) Posts: 116 Joined: |
This why your OP question does not make much sense. 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?
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Stagamancer Member (Idle past 4915 days) Posts: 174 From: Oregon Joined: |
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. Survival of the species is not a target of evolution. Traits can be selected for that are good for the individual but bad for the species. For example, a very virulent virus will reproduce very fast, and create tons of progeny. These will go on to do the same. Eventually that virulent phenotype will be the only one left in the virus population. Therefore, evolutionary biologist would say it's been "selected" for. However, if the virus is too virulent, it will destroy the host population it depends on for reproduction. Once this happens, the virus population will die out too. In this way, evolution can lead to the extinction of a species, not the survival of it. There are also examples of the opposite happening, but my point is that survival of a species is not the target and is not the only result of evolution. The reason evolutionary biologists focus on reproduction is because differential reproduction is how individuals win the evolutionary "game". It's all about the numbers. Those that reproduce the most will have the greater share of the population. If that trend continues, i.e. the offspring of that one individual continue to reproduce more than any others, then they will eventually be the only ones left in the population. The phenotypes that allow an individual to reproduce more offspring than the others in its population will increase in frequency in the population. This is all natural selection is. It's not actually an active force like the term 'selection' would make one think. So, reproduction is a requirement for evolution to occur, but it is also the only metric by which evolutionary 'success' is measured.
Does anybody know when in biology two species are considered separate?
Ah, this is a very deep question, and one that has not been resolved in the biological community. Species is a tricky concept. There are many different species definitions out there, and none has been chosen as the best. The most popular is the Biological Species Concept (BSC) which, to paraphrase significantly, says that two individuals are of the same species if they can produce viable offspring (often the caveat is added that this must also be something that occurs naturally in their usual habitats, not just in zoos or labs). However, as I'm sure you can see, this definition is far from perfect. What about asexual species, like bacteria, which account for more species than all the other types of life combined? What about species that form viable hybrids with other species? There are at least a couple dozen other definitions that you could find on wikipedia, and I won't go through them here. The point is that species does seem to be a real concept in natural world to some degree. What I mean by that is that the concept of species is not purely an artifact of human categorization (like it would be if we considered all organisms of the same general color the same species). However, what we call species tend to fall onto a fine spectrum going from "good" species - those that strictly adhere to a species definition, such as the BSC - to "poor" species - asexual species and those that form hybrids with sister taxa all too readily. So, when is the exact moment that one species becomes another? Well, there probably is no exact moment, and the more finely one tries to look at the question, the harder it becomes to answer. I find it akin to asking at what point on the light spectrum does red become orange? Wikipedia says at 620 nm. But at exactly 620 nm is it red or orange? Could anyone tell the difference between 619.5 nm and 620.5? The point is that there is probably no exact moment, but it does happen. At some point during speciation, two populations that were once one species are two separate species. This happens due to a whole set of reasons that you can read about elsewhere. The point though, is to emphasize that evolution is not trying to preserve species. Evolution happens because of differential reproduction, and natural selection is measured by determining how differential the reproduction is. We have many intuitions in our life and the point is that many of these intuitions are wrong. The question is, are we going to test those intuitions? -Dan Ariely
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adelpit346 Junior Member (Idle past 5099 days) Posts: 11 Joined: |
while the appearance of evolution is created by THeLORd1JESUs
the only evolution that does exist is when a man is translated that is a physical evolution the angels in third heaven are all created individually and as such are not related to each other but are still servants to THeLORd1JESUs as they are like children they have the consideration towards each other that the children of men/wheat have but grown wheat men wise in tribulation are far more considerate towards each other than the angels are for they do not suffer tribulation but man/wheat is given to arise out of adam and eve to create family so that being physically related we might find it within our souls/conscious minds to have more consideration for each other than the angels did for so they war vigoriously for 750 million years iamnothing0 JESUsISTHeLORd1amen
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Coyote Member (Idle past 2106 days) Posts: 6117 Joined: |
You are not off to a very good start here.
Care to settle down and try again? Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.
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adelpit346 Junior Member (Idle past 5099 days) Posts: 11 Joined: |
i reviewed what i have written
it is correct the truth is unsettling to the insane predestinated wheat FATHER forgive them of they know not what they do this is the best start i have yet made in any high spiritual placedo not hold it against yourself that you do not understand these things making this the 1516th excommunication will not offend me:')
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Coyote Member (Idle past 2106 days) Posts: 6117 Joined: |
...making this the 1516th excommunication will not offend me:') Sorry to hear that. It should. In fact you should feel real shame for acting like such a jerk. Religious belief does not constitute scientific evidence, nor does it convey scientific knowledge.
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AZPaul3 Member Posts: 8513 From: Phoenix Joined: Member Rating: 5.3
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It is apparent that T1>T2, Mechanics. In your example time t1 is less than t2. t1 < t2 The '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.
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bluescat48 Member (Idle past 4189 days) Posts: 2347 From: United States Joined: |
i reviewed what i have written it is correct Evidence please. There is no better love between 2 people than mutual respect for each other WT Young, 2002 Who gave anyone the authority to call me an authority on anything. WT Young, 1969 Since Evolution is only ~90% correct it should be thrown out and replaced by Creation which has even a lower % of correctness. W T Young, 2008
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MrQ Member (Idle past 5052 days) Posts: 116 Joined: |
Therefore, evolutionary biologist would say it's been "selected" for. However, if the virus is too virulent, it will destroy the host population it depends on for reproduction. Once this happens, the virus population will die out too. In this way, evolution can lead to the extinction of a species, not the survival of it. 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'.
The reason evolutionary biologists focus on reproduction is because differential reproduction is how individuals win the evolutionary "game". It's all about the numbers. Those that reproduce the most will have the greater share of the population. If that trend continues, i.e. the offspring of that one individual continue to reproduce more than any others, then they will eventually be the only ones left in the population. The phenotypes that allow an individual to reproduce more offspring than the others in its population will increase in frequency in the population. 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 ...
So, when is the exact moment that one species becomes another? Well, there probably is no exact moment, and the more finely one tries to look at the question, the harder it becomes to answer. 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
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MrQ Member (Idle past 5052 days) Posts: 116 Joined: |
Mechanics. In your example time t1 is less than t2. t1 < t2 That's was mistake. Thanks for pointing it out.
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. 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.
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. 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.
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Taq Member Posts: 9972 Joined: Member Rating: 5.5 |
You need to consider that 'survival' depends on two forces. One is reproduction and the other death. As it turns out, those who who survive to reproduce tend to have the fittest genes. Genetics is a force as well.
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Taq Member Posts: 9972 Joined: Member Rating: 5.5 |
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. Without reproduction the species would still die out in a single generation, even if that generation lived twice as long as the last. Also, without differential reproduction the number of individuals with the advantageous gene would stay the same generation to generation.
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.
How can you talk about genetics changing within a population over time without involving reproduction? Care to explain?
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. Care to give an example within biology? For example, if the wing for a vertebrate were a target then why are the flying fish wing, the bat wing, and the bird wing so different?
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. You have a lot of different concepts all muddled together. Are you saying that an electron in an oxygen atom has the goal of water in mind before it comes in contact with a hydrogen atom? Perhaps a better analogy would be the game of craps. Are the probabilities of specific role increased when someone makes a bet on it? For example, if I put my bet on the Pass line on the come out roll do the odds increase for rolling a 7 or 11? They don't, do they. The dice are not trying to meet a goal. Evolution is the same way. The mutations that occur are not aimed at a specific target. They are random in the same way that the roll of the dice is random with respect to the bets on the table. The mutations that get passed on to the next generation are the mutations that work, no matter how they work.
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MrQ Member (Idle past 5052 days) Posts: 116 Joined: |
As it turns out, those who who survive to reproduce tend to have the fittest genes. Genetics is a force as well. 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 -1 What 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, : spell Edited by MrQ, : No reason given.
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Blue Jay Member (Idle past 2697 days) Posts: 2843 From: You couldn't pronounce it with your mouthparts Joined: |
Hi, MrQ.
Welcome to EvC!
MrQ writes: 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. This is incorrect. Trends in the overall system do not necessarily apply to the individual parts of the overall system. This called the fallacy of division. What you are seeing is really the appearance of "reason and direction" in the overall system. When we look at a smaller scale---at the individual parts of the overall system---what we realize is that the appearance of reason and direction results from a combination of many unreasoned and undirected processes. So, in reality, the reason and direction is just an illusion. Since the reason and direction are not actually real, the thing you are interested in discussing doesn't actually exist, except as a metaphor that is a useful way to help new students visualize the process. -Bluejay (a.k.a. Mantis, Thylacosmilus) Darwin loves you.
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Taq Member Posts: 9972 Joined: Member Rating: 5.5 |
But when we say we have competition in species then we have to see what is ultimately is changing? That would be the genetics of the population as a whole.
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. Why doesn't it make sense to include the primary parameter in an equation? It would seem to be required. Survival is defined in relation to reproduction. Survival doesn't mean living the longest. It means having the most grandchildren. It means survival of your genes, and this is dependent on reproduction and the reproductive fitness of your children. If death occurs after having tons of children death doesn't matter as long as your death does not affect the passage of your genes from your children to your grandchildren. For example, salmon die right after they spawn. Their death does not impact the next generation. Death is meaningless in your equation without first relating it to reproduction.
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. Dying before you can reproduce does affect the reproduction rate. On average, the sunlight resistant bacteria will have more offspring than the sunlight sensitive bacteria due to having more offspring.
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. No, that is the unavoidable outcome. There is no target, per se. You might as well claim that rivers in the Western US have the Pacific Ocean as a target. This would be wrong. The unavoidable consequence of gravity is that water will drain to the lowest elevation.
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