Lande (1988) speaks of a view, promoted by Soule and Simberloff (1986), and in Soule and Wilcox (1980), that "genetic variation can be adaptive in and of itself".
Can anybody clarify what this statement means? How can genetic variation itself, be adaptive?
What these authors are talking about is the adaptive quality of having genetic variation in a population. Compare to e.g. a clone in a ramet. There is no genetic variation and no quantitative variance, so that a sudden environmental pressure for which there is no genetic contingency will wipe out the ramet. Therefore, the adaptation is to have genetic variation in a population, most notably via sexual recombination, so that the entire population is not wiped out when the environment changes. Extrapolate backwards in time, and you could arrive at the conclusion that the first populations that displayed some kind of mechanism to increase genetic variation, must have been the populations that were able to transmit that capability through genetic bottlenecks due to selective pressure. Those that did not have that capability are no longer around. Disclaimer: This is true for most species, but not all.
Right, that clarifies it. I didn't think that genetic variation could be considered adaptive, almost as if it were a trait in itself. But that's exactly how these authors have phrased it.
These authors probably come from a quantitative genetics background (I don't know them personally so I'm not sure). In quantitative genetics, the "average phenotype" is a result of "average genotype" and "average environment", and disregarding a few curveballs like pleiotropy, any characteristic of the population can be seen as part of the phenotype. To clarify, you can consult The Extended Phenotype by Richard Dawkins.
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