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John Paul:
A mutation, any mutation, has a better chance of getting lost in a population than it does becoming fixed.
If this were not true, the genetic load of mutations would become somewhat of a problem.
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As we know most mutations are either harmful or neutral, why would these mutations even be selected?
Neutral mutations aren't, and negative mutations are actively removed from the population through the disproportionate death of those indivudals who have them.
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Beneficial is a relative word as there is no way to predict what would be selected for at any point in time.
Certainly there is. A change in the survival traits of an organism which gives it an advantage relative to its peers will be selected. These can include features such as better camoflage, smaller size to avoid detection of predators, larger size to discourage predators, etc. etc.
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What may be beneficial for one generation may not be beneficial for future generations
And conversely, what may be beneficial for one generation will commonly be beneficial for future generations.
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However I am open to any evidence that shows that more than 1 beneficial mutation can become fixed in a population in a shorter timeframe.
http://www.gate.net/~rwms/haldane.html#solutions
The basic criticism of Haldane's supposed "dilemma" is that it is an outdated and basically invalid model of how population genetics works.
The specific problem with it is that it posits a 'replacement cost' that assumes that for each mutation to be fixed in a population, the rest of the individuals in the population with the existing version of the gene must be eliminated.
This scenario, however, is only valid in instances where the selection pressure on a particular gene is very very high, as in the case of rapid environmental change.
The more common scenario is that of a large number of mutations entering the genome, being winnowed to a very small number first by sexual selection and natural selection, and becoming fixed in "pipeline" fashion over the course of a few dozen generations. In this manner, each generation fixes a new set of mutations which are the end product of a much larger set of raw mutations which entered the genome many generations ago.
This is how real ordinary population genetics works, and it is the basis for the modern theory of evolutionary genetics, and results in a vastly larger number of differences than Haldane's faulty model.
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Also becoming fixed might not even be enough. What happens when an organism with this new mutation mates with an organism without it?
This is a non-sequitur. A fixed gene is one in which only one version of a particular nucleotide in a population exists.
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And yes the 1667 is derived using Haldane's dilemma. If you think it is faulty perhaps you should start a thread to explain why you think it is.
Haldane's model is kept alive only by creationists. Why don't you spend some time making the argument as to why creationists seem to ignore the rest of the body of population genetics since Haldane, and the obvious problems with his early model.
[This message has been edited by Rationalist, 08-18-2002]