Rob Skipper has a relatively accessible post on what Fisher and others think the Fundamental Theorem of Natural Selection means. The old joke has it that it's neither fundamental nor a theorem, but Rob goes into more detail based on a seminar he and his students did.
One thing - "genic variance" is undefined. As I understand it, that is the amount of phenotypic variation in a population that is due to genetic differences between individuals. Thats the definition I could find, anyway.
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I'll admit I generally assume people know enough biology to follow my posts. (It's my research notebook, after all, not my text book.) At any rate, Fisher's 'genic variance' is sort of defined in the paragraph I quote by Edwards as the 'additive genetic variance'. Of course, I'll give you that that's not defined. But I wouldn't use the definition you give. Here's one: it's the genetic variance associated with the average effects of substituting one allele for another in isolation of genetic context.
That definition makes things clearer, at least as long as you know what to make of average effects and allele substitutions in isolation. Not an easy task since there's no biologically "real" measure of such.
Those who do not know much biology, in this case me, don't understand the difference between additive variance and, well, whatever it is that is not additive (linked? epistatic?) and need some hand holding here. Do it nicely, and I'll add it to the Basic Concepts series list.
The non-additive genetic variance can be dominance or epistatic variance (and epistatic can be divided into additive by additive, additive be dominance etc.).
Bruce Walsh has a lot of his lecture notes on the web, which might be of help. Although just the idea of writing a Basic Concepts article on dominance variance makes me want to weep.
Bob