Dahl continues and he sees everywhere advantages, protective means etc. Some quality has advantage and an opposite quality has it too.
Which is why natural selection is not dependent solely on the organism, but on the relation of the organism to the ecology. When you only look at one side of an equation you will always fail to solve it.
We can not use words like contribution or by individuals.
We can. Natural selection operates on the phenotype of individuals, whether it is survival, disease, disability or sexual reproduction.
Those that survive and reproduce contribute to the genetic composition of the population of the next generation. Those that do not make no genetic contribution.
What follows is a Little bit of history here and my point of view: The change in structure leads to genotype changes as well and vice versa.
Nope. There is no mechanism by which any change in structure can be transmitted back to the genotype. None. This concept -- essentially what is known as Lamarkism -- has already been falsified because of this.
With 6 limbs the species will have to change the behaviour as well ....How to hunt ? How to defend ? How to involve in Sex ?
Insects manage it quite well.
This is the typical need based reasoning which is needed for phenotype stability.
Need based reasoning is also false. There is no response to "need" in biological evolution, there is only response to ecological changes and opportunities.
Therefore we find a concept of non-random mutation.
This too is falsified by genetic research. Mutations are random. Random in where and when they occur. There are mechanisms by which organisms under stress can increase the rates of mutation, but this has no effect on the kinds of mutations that occur.
A radom mechanical (which can be fitted into machine) leads to a non-random and non-mechanical manifestation of selection. This is impossible. All logical constructs are inconsistent and incomplete. Precisely it means a machine can not come out of loops on its own. (e.g loops : This statement is false. ) As a machine can not think.It simply executes the algorithm and the statement can not be answered by any Universal Truth Machine.
Sorry, I don't follow what you are trying to say here. Organisms are not machines. Machines don't reproduce and thus aren't affected by natural selection.
I have a solution for this. The assign a purpose to the evolution of life. All life forms work towards sustainable pleasure. TSP is the backbone of my theory of evolution... So far the theory has explained everything which the Dawkins theory can explain.It may need a sperate thread to discuss. Or you can create a Thread : Do you believe that pleasure is the root cause of evolution ? and we will discuss.
I suggest a new thread where you lay out what your theory is and how it applies. Most critical would be how you would test the theory against observations to show your theory would have a different objective outcome than biological evolution (whether expressed by Dawkins or Mayr or whoever is irrelevant - it has to measure against the science of biologial evolution).
As per current theory there can not be any desire to contribute to genetic compostion.(Infact from TSP point of view there is no such desire but even without desire it turns out that phenotype genes will be extra stable.)
All it takes is reproduction of surviving organisms. Nothing more is needed to account for the evidence.
Does NS “operate” on the phenotypes of individuals, like a surgeon who operates on a patient’s liver? Or does it “operate” instead on the reproductive success of populations? NS engages when that success is not uniform across individuals?
When an individual dies the rest of the population is unaffected. When an individual reproduces the rest of the population is unaffected. Natural selection therefore operates on the individual as expressed in the phenotype based on their genotype.
Whatever alters a population’s uniform success in reproduction may have multiple causes”environmental factors, mutation, gene flow”and NS may not always, or not even often, play the lead role in evolution.
The effect on the population is the sum of the effects on the individuals, and there is no effect on the population that is then transmitted back to individuals to affect their existence.
...and there is no effect on the population that is then transmitted back to individuals to affect their existence.
I don't entirely get this. Who ever said that, anyway?
That is what you would have to see happen IF natural selection operated on the population.
So, NS occurs where exactly? In the population or in the individual?
In the individual. When an individual dies the rest of the population is unaffected. When an individual reproduces the rest of the population is unaffected. Natural selection therefore operates on the individual as expressed in the phenotype based on their genotype.
I simply do not understand that statement.
Is your fitness to survive or ability to reproduce affected by the ability of someone across town to to survive or reproduce? Selection is on the individual.
... there would need to be an elapse of time while gestation occurres.
No, we can be pretty sure that with only one child per couple that only half of the genes of the population will be transmitted to the offspring. This type of change would normally be labeled genetic drift, however in this case it is caused purely by the choice to have only one child per couple. Thus the choice to have only one child per couple resulted in a change in the hereditary traits in the population.
In a normal population the number of children would vary (as would the chosen mates) and this too would be natural selection.
So you have mate selection (no sexual selection) and natural selection. Not what you were thinking eh?
Let’s go to The Origin of Species (pp. 56 & 57 of my edition)”:
quote: ... Thus it is rendered possible for the two sexes to be modified through natural selection in relation to different habits of life, as is sometimes the case; of for one sex to me modified in relation to the other sex, as commonly occurs. ...
I could argue that he is talking about a subset of natural selection, but it doesn't matter that much to me.
quote: ... sexual selection. This form of selection depends, not on a struggle for existence in relation to other organic beings or to the external conditions, but on the struggle between the individuals of one sex, generally the males, for the possession of the other sex. The result is not death to the unsuccessful competitor, but few or no offspring. ...
You don't have this in your scenario, so by the definition that you refer to there was no sexual selection.
Thus the changes in hereditary traits is not due to sexual selection .... take a guess?
Let me add that several of the couples would have lost the first zygotes (happens all the time) and some may even have had miscarriages. These are instances of natural selection operating on non-viable genetic combinations. Those genetic combinations are not represented in the new generation due to selection.
The distinction made by Darwin (above) is that what is referred to as sexual selection is an additional mechanism within the overall natural selection process which differs from sexual reproduction in species where no such selection takes place. Thus no matter how you cut it natural selection involves mating and reproduction and the subsequent changes to hereditary traits in the population
Natural Selection ” its power compared with man's selection ” its power on characters of trifling importance ” its power at all ages and on both sexes ” Sexual Selection ” On the generality of intercrosses between individuals of the same species ” Circumstances favourable and unfavourable to Natural Selection, ...
That's the table of contents, and sexual selection is in the chapter on natural selection ... that looks like he regards it as a part of natural selection.
It is also generally accepted in the modern biological evolution that sexual selection is a part of natural selection. Natural selection would be a compendium of selection mechanisms that differentiate one organism from another.
... then do you also include mutation, random genetic drift, and gene flow as said same "addition mechanisms" of NS?
Part of evolutionary biology yes, part of a selection process no.
But I also don't lose sleep over it. One just needs to be specific when they talk of such things in order to be clear in the presentation of ideas.
Still doesn't say different, that is your issue eh? The whole chapter is on Natural Selection, part of it is on sexual selection, because sexual selection is a - less rigorous - subset of natural selection.
The trapezoidal rule is a less rigorous way to approximate area under a curve than the simpson rule, but both are ways to approximate area under a curve.
Take away that one sentence and see if he compares natural selection to sexual selection before coming to that conclusion.
Natural Selection ” its power compared with man's selection ” its power on characters of trifling importance ” its power at all ages and on both sexes ” Sexual Selection ” On the generality of intercrosses between individuals of the same species ” Circumstances favourable and unfavourable to Natural Selection, ...
The chapter is not titled "Selection" but "Natural Selection" ...
... and it is still rather silly to argue about this when modern biological evolution regards sexual selection as part of natural selection (selection mechanisms that occur naturally).
quote:It is also useful to make a mechanistic distinction between ecological selection and the narrower term sexual selection. Ecological selection covers any mechanism of selection as a result of the environment (including relatives, e.g. kin selection, and conspecifics, e.g. competition, infanticide), while sexual selection refers specifically to competition between conspecifics for mates.[9]
As we are getting near the magic 300 post limit, I thought I would summarize my position.
Re the OP:
I have been saying that NS is the differential reproductive success amongst invividuals of a population. This agrees with E. O. Wilson's defintion (from Sociobiology, 2000, p. 589):
quote:Natural selection: The differential contribution of offspring to the next generation by individuals of different genetic types but belonging to the same population.
He does not mention sexual selection, mutation, gene flow, or drift in his definition; he only refers to the differential reproductive success amongst individuals in a population.
I don't have any real problem with that. I think EO Wilson needs to consider the phenotype as the expression of the genotype within the environment as the real object of selection, but this problem is not part of your phraseology.
Mutation is not a selection mechanism, it provides the depth of opportunity within the population for selection to operate on.
Genetic drift is not a selection mechanism per se but a result of stochastic factors (random chance).
Gene flow would change the distribution of hereditary traits within subpopulations (that's where gene flow goes) and it would be subject to natural selection in the process of making that "flow" from one subpopulation to the next. It would not be a selection mechanism of itself.
Sexual Selection.
As discussed, sexual selection is a part of natural selection that deals with differential mating success, as opposed to plain reproductive success, due to factors that relate specifically to mate selection. Because "differential reproductive success amongst invividuals (sic) of a population" occurs with sexual selection it is de facto a mechanism of natural selection.
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