Professor Moran: I think that natural selection played an important role in all of those events. Or is it simply your contention that natural selection, while not playing an important role in the origin of complex structures and novel morphological features, exerts a refining and purifying effect subsequent to their appearance, weeding out non-viable life-forms? Professor Moran: No. I have always contended that natural selection plays an important role in the origin of most complex structures and novel adaptive morphological features.
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For whatever reason, Larry chose to be silent on this difficult and inconvenient issue about the Neutral Theory because, I presume, he wanted to read the book first. It would be enlightening, if Larry and John would be willing to discuss the significance of Neutral Theory and the Mutation Theory in explaining evolution. Emphases mine — VJT. Professor Moran replied :.
Geerat Vermeij, Evolutionary Biologist
Claudiu Bandea persisted with his question, asking Professor Moran:. Parts of his new book are accessible via Google books. I was tipped off by a hint provided by biologist Kenneth M. Professor Nei is no friend of Intelligent Design; he explicitly states in the last sentence of his book p. The conclusions we have reached may be summarized as follows.
Selective advantage of a mutation is determined by the type of DNA change, and therefore natural selection is an evolutionary process initiated by mutation.
Leaning on the Spleen
It does not have any creative power in contrast to the statements made by some authors. However, selective advantage of a mutation is also dependent on the set of other genes and the environmental conditions, the latter varying from generation to generation. It may or may not be associated with the increase of fitnesses number of offspring per individual , and therefore evolution can occur by neutral genetic processes such as gene duplication and gene co-option as well as by natural selection.
Because of this functional constraint , most mutations occurring in a gene are deleterious and eliminated by purifying selection. These mutations occur with a low frequency at functionally important sites. A gene cannot have any function without having interaction with other genes. Therefore, constraint-breaking mutation may be controlled by many gene loci.
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The innovational change of phenotypic characters is generated when constraint-breaking mutations occur at the genomic level. There is a considerable degree of flexibility in genomic constraint so that diploid individuals with two different genomes can survive without trouble within a species. However, if two different populations are isolated for a long evolutionary time, interpopulational hybrids become inviable of sterile because of genomic incompatibility. This hybrid weakness occurs because the genomes of two populations evolve independently and therefore the compatibility of genes between different populations gradually declines.
No positive selection is necessary for the establishment of hybrid sterility. Therefore, most organisms can live in a range of ecological niches , which can be called the ecological survival range. For this reason, a species may flourish easily in a new territory to which it was transferred. If a species moves to a new habitat e. Neomutationism or the theory of mutation-driven evolution is also different from the classical mutationism, because it covers not only genic mutations but all kinds of genomic change including genome duplication.
In neomutationism, the molecular study of mutational change as well as the selective advantage of new mutations are emphasized. Therefore the cause of mutation is no longer treated as a black box. For these reasons, neomutationism or the theory of mutation-driven evolution is applicable for much wider biological situations than classical mutationism and at the same time demands a more sophisticated molecular approach….
At the present time we have little idea about the evolution of the human brain or even less complicated characters such as parental care in some mammals. However, the evolution of these characters will eventually be clarified at the molecular level….
In the study of phenotypic evolution it is important to realize that there are two evolutionary forces operating at the genomic level. One is the genome conservation force that maintains the developmental integrity of genes within individuals and the reproductive unity of individuals within species or populations….
The other evolutionary force is the genomic diversification of different species. This occurs because many constraint-breaking mutations are species-specific and these mutations contribute to the diversification of different species. From the foregoing passage, it should be apparent that Professor Nei envisages his neomutational theory of evolution as a comprehensive theory of evolutionary change, which can ultimately explain even the evolution of the human brain at the molecular level.
This is radically different from the more conservative position defended by Professor Moran in his replies to my five questions. The critical question that needs to be asked is: can he demonstrate mathematically that the constraint-breaking mutations he envisages are capable of generating the kinds of structural, behavioral and molecular complexity that we observe in the world of living things?
Charles Darwin said evolution occurs by natural selection in the presence of continuous variation, but he never proved the occurrence of natural selection in nature.
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But among the people working on evolution, most of them still believe natural selection is the driving force. If you say evolution occurs by natural selection, it looks scientific compared with saying God created everything. You have to explain how. Mutation means a change in DNA through, for example, substitution or insertion [of nucleotides].
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First you have to have change, and then natural selection may operate or may not operate. I say mutation is the most important, driving force of evolution. Natural selection occurs sometimes, of course, because some types of variations are better than others, but mutation created the different types. Natural selection is secondary….
Kimura believed morphology [appearance] evolves through natural selection. He applied neutral theory only on a molecular level. I say it can determine morphological characteristics as well because DNA determines everything, but to prove this has not been so easy. But any time a scientific theory is treated like dogma, you have to question it. The dogma of natural selection has existed a long time. Most people have not questioned it.
Most textbooks still state this is so.
Most students are educated with these books. You have to question dogma. Use common sense. You have to think for yourself, without preconceptions. In my post, Will the real Neutral Theory please stand up? I then quoted the following remark by Dr. Korthof, in which he expressed his own opinion on the neutral theory of evolution:. In that sense it is not a theory of evolution. Emphasis mine — VJT.
In a footnote to his recent blog post , Professor Moran, in response to a complaint by Dr. However it is accepted that the neutral theory explains a lot of differences in DNA. It seems that evolutionists need a basic lesson on what quote mining is. In my post, I provided a direct link to Dr.