I just noticed how well the Hardy-Weinberg principle suits the definitions of the terms. Wonderfully, they seem to have encompassed all possibilities, but the five (or six) mechanisms of change seem to overlap on the scenarios they can describe. Could biologists simplify the concepts into something more partitioned, perhaps to aid the deduction of causes?
Natural selection and genetic drift primarily concern whether individuals reproduce, and subsidiarily whether individuals survive. In contrast, mate selection concerns not only whether, but also with whom an individaul mates. Gene flow too concerns the ‘with whom’ question of mating, and it describes another way in which individuals can come and go without actually being selected.