I advocate that approach as well. By this, "mutation" can be
understood to mean that something is different or has changed
in DNA sequence of an organism.
For instance, recombination shuffles the sequences of chromosomes
and introduces different sections of DNA to new contexts. This
can result in changes in expression or even in the creation of new
gene combinations. An obvious case is when recombination occurs
between alleles with point mutations at different positions in
a gene. Here, an allele with both sets of mutations can be generated.
> variability plays an important role over the long term, ... but
> I see this as the effective use of the complex cellular machinery.
> How do we know that "mutations" (malfunctions) play an important
> role? If it is so important, it has presumably been well studied -
> and there should be no difficulty finding dozens of examples to
> support the hypothesis. However, I am not aware of the long list
> and am very skeptical about its reality. (Hence, by putting all
> sources of variability under the heading "mutation", an important
> distinction in the sources of variability is obscured).
[...]
Base changes can play very critical roles. For instance, the
high mutation rates of many viruses (HIV is a prime example)
contributes to their ability to reproduce and survive in their
hosts (and host populations). There are numerous pathogens that
rely on mutations (including base changes) to generate the variability
needed to evade host responses. There are other cases where
base mutations are an important source of genetic variability,
but I think that the host/pathogen literature is probably the
richest source of such examples (Human health and food production
being the primary drivers for that research).
Regards,
Tim Ikeda
tikeda@sprintmail.hormel.com (despam address before use)