Evolution: a different view with loss of traits; not Behe (Introduction)

by dhw, Sunday, September 06, 2020, 12:22 (1539 days ago) @ David Turell

DAVID: The big issue is if advances always result from the loss of genes the info was available and revealed in the DNA with each step.

dhw: I challenge the view that advances ALWAYS result from loss of genes! I suggest that the process is on-going, with a constant acquisition of new genes (or new functions for old genes) and loss of unwanted genes. Natural selection merely decides which genes are necessary and which are not.

DAVID: Natural selection has nothing to do with genes directly!!! You are challenging two sources of advances in form and function through the gene loss concept: Behe's book, filled with examples and an article that lists many studies but never mentions Behe's ideas. How can you challenge it? From previous bias is obvious.

dhw: What do you mean by “directly”? If certain genes are no longer required, it is perfectly “natural” that they should disappear. I am puzzled by the theory you have presented, so instead of asking why I challenge it, perhaps you would enlighten me by explaining why my bolded proposal above is impossible.

DAVID: Your proposal is wishful, but not supported by anything in the article I presented or by Behe's book. Facts are facts. DNA Loss is now known and supported by a source (quoting multiple studies other than Behe). The last of Darwin worship is dying.

(I’m skipping the discussion on Darwin. It’s totally irrelevant to our subject.)

DAVID: Your bolded proposal ignores the point of the article. It is now accepted that new mutations (new genes) are most always deleterious or if effective lead to minor alterations of no major consequence to furthering evolution. If read carefully, the article is in full support of Behe.

We are not talking about deleterious mutations but about gene loss. I challenged your statement that “advances ALWAYS result from loss of genes”. Look at the title: “By Losing Genes, Life Often Evolved More Complexity”. Often, not always.

DAVID: Quoting the title and subtitle:
By Losing Genes, Life Often Evolved More Complexity
Recent major surveys show that reductions in genomic complexity — including the loss of key genes — have successfully shaped the evolution of life throughout history.
https://www.quantamagazine.org/by-losing-genes-life-often-evolved-more-complexity-20200...

Here are some quotes from the article:

But in reality, the majority of gene losses during evolution are likely to be neutral, with no fitness consequences for the organism…

The reason is that evolutionary gene losses often occur after some change in the environment or behaviors makes a gene less necessary. If a key nutrient or vitamin suddenly becomes more available, for example, the biosynthetic pathways for making it may become dispensable, and mutations or other genetic accidents may make those pathways disappear. Losses can also occur after a chance gene duplication, when the superfluous copy degenerates, since selection no longer preserves it.

Of course, the risk of evolving by jettisoning genes is that even if a gene is dispensable in particular environmental conditions, it might be needed again millions of years later, Jedd says. What then? It turns out that yeasts, at least, can sometimes get genes back.

Please note the emphasis on the influence of the environment, the necessity or otherwise of the gene (he uses the term "dispensable"), and the role played by selection. There is nothing in the article about innovation. It deals with adaptation. Under the photo of the author, we read: "Cristian Cañestro, a professor of genetics, microbiology and statistics at the University of Barcelona, has argued for years that gene loss can be an adaptive evolutionary force."

There is absolutely nothing in this article that contradicts my proposal bolded above.