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In an creationist article, about molecular virologist, Dr Yingguang Liu, it says:

Evolutionists commonly invoke ‘duplication’ as a way to create brand new genes. A copying error can lead to an extra copy of a gene, which supposedly can then go on to evolve into something else (‘neofunctionalization’) without compromising the original gene. Dr Liu discussed what happens after a theoretical duplication, and the picture was not pretty for evolution. [reference 1] First of all, degeneration is expected, because a non-important (‘neutral’) gene can freely mutate or even be deleted with no threat to the organism. With no selection pressure to maintain the gene, the opportunity for neofunctionalization is quite limited. Also, the main difference between the various forms of life is how genes are regulated, not the number of genes. Gene duplication does not help evolutionary theory.

Are some new genes created through the mechanism of gene duplication?

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    There are too many claims made in this question. Are genes duplicated? Are there copying errors? What is the result of mutation? Does lack of selection pressure "maintain" a gene and limit further mutation? Is the regulation of genes more significant than the inventory of genes? This is a typical creationist "claim" - it's actually ten or more misunderstood scientific principles all mushed together. A proper debunking of this would be really really long. Please be more specific.
    – Jasmine
    Commented Jan 6, 2017 at 19:44
  • Further to @Jasmine's concerns: all the preceding statements might be true, but the final conclusion be wrong.
    – Oddthinking ♦
    Commented Jan 6, 2017 at 23:59
  • I've refocussed the question to try to avoid this problem. @Jasmine: Does that satisfy your concern?
    – Oddthinking ♦
    Commented Jan 7, 2017 at 0:02
  • You should ask on biology.stackexchange.com. In short, yes, duplication occurs in several forms, so therefore a mutation in one copy will not affect the expression of the other. Sometimes the duplication itself is harmful (e.g. Down Syndrome) but other times not (e.g. hexaploid wheat).
    – user11643
    Commented Jan 7, 2017 at 3:08
  • This is less a skeptics question than a biology and definition-of-terms question, methinks... The objection is based on a misunderstanding, nothing more.
    – keshlam
    Commented Jan 7, 2017 at 16:45

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Gene duplication is a very important way of creating new genes and hence it helps organisms to evolve.

Once a gene is duplicated, the "spare" copy of the gene is effectively not needed by the cell, as the original still does the required job. This leaves the copy free to mutate in whatever way it wants. If it is a deleterious mutation, then the copy will eventually be weeded out by natural selection. However, if the mutated copy is advantageous it will be kept. This mutated copy can produce features that the original cell did not not have, and hence create new species. Contrary to creationist claims, this can even happen with "degenerated" genes.

That this has happened is a fact. One documented example occurred with biologists' preferred animal: fruit flies (Drosophila). According to the authors of this paper, DNA analysis of Drosophila melanogaster revealed a new gene family that originated 1 to 2 million years ago. It was formed when the original genes were duplicated by retrotransposition. Through fission, these genes underwent partial degeneration to create the new mkg (monkey king) gene. According to the authors, "The mechanism underlying this process is gene duplication with subsequent partial degeneration."

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