Gradualism in Evolution not supported by genome studies (Agnosticism)

by dhw, Saturday, October 10, 2020, 08:42 (1505 days ago) @ David Turell

dhw: I would like to make a slight change to my proposal, in direct opposition to the theory I have been objecting to: Speciation is caused by the acquisition of new genes AND new functions for old genes, and is ACCOMPANIED by loss of unwanted genes etc.
If you now accept my revised proposal, I think we can close this thread.

DAVID: I do not agree fully with the bold above. Loss of genes appears to be one of causes of speciation along with a restructuring of expression of genes and may include new genes added. But based on Behe, some speciation changes are just deletion.

A restructuring of expression of genes is what I call new functions for old genes. This whole discussion began with my disputing the claim that “advances always result from loss of genes”. I only know Behe’s theory from what you tell me, so I don’t know if his examples are minor variations or totally new species. I remember you picking on the example of the polar bear lacking two genes found in the grizzly and the brown bear. I wouldn’t call this an advance. They are all bears, but they live in different conditions, and had to adapt accordingly. The obvious inference is that genes which operate in a warm climate won’t be of any use in a cold climate. I can’t see the logic in the argument that losing useless genes will create a new fur coat. But I can only discuss the points you reproduce here. Since we do in fact call these different bears different species, perhaps we shouldn’t be using the word “speciation” at all and should stick to the term used in the latest article: “major evolutionary transitions”, which I would equate with innovation and which, you will remember, occur when “vast numbers of existing genes are jettisoned and replaced by entirely different ones”. But I would also expect loss of genes as a RESULT of minor transitions and not as the cause.