I'm afraid like most people I suffer from having learned "A History of Evolution" in school, rather than cutting to the chase and learning the actual "up to date" version of the subject. (Imagine if programming classes did the same thing and you were forced to learn FORTRAN and BASIC before learning JavaScript) So please help me fill in some gaps:
From what I have been taught, Natural Selection (or even Artificial Selection) is great for panning favorable genes from a species and bringing them to the fore, however, it does not introduce new genetic changes.
It is possible to introduce new genetic changes through mutations. When asexually reproducing organisms receive a mutation, they pass that mutation on to their offspring. Mutations are somewhat rare, and beneficial mutations even less so, but happen frequently enough to make a dent over a long period of time.
The problem I don't understand is with larger organisms, aren't those already rare mutations only passed onto offspring if they occur in the short-lived sperm or egg cells of one of the parents*? At the very low probability of a beneficial mutation occurring in a single cell of a male's leg, not only is it unlikely he would benefit by this mutation, but even if the male reproduced, this mutation wouldn't be passed on, and would die with the male.
Are mutations viable methods to introduce new variations in more "complex" organisms that reproduce sexually? Or is there another theory or system that bridges Natural Selection and Mutation Theory in larger organisms?
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