 In other words, various very detailed environments would have to be specified for various different t-alleles and wild-type alleles. In order to determine the invariant fitness parameter of a specific allele, let’s call it “A” for example, we would need to know what kind of environment it is in at the allelic level, e.g., whether it is paired with a t-allele. Then we would need to know a further detailed layer of the environment of “A”, such as what the sex is of the “environment” it is in. If it is in a t-allele arrangement, and it is also in a male environment, the allelic fitness of “A” would be changed. Finally, we need to know the type of subpopulation or deme the “A” allele is in. Is it in a small deme with many t-alleles? Then it is more likely to become extinct. So, as we can see, various aspects of the allele’s environment are built up from the gene out, depending on what would make a difference to the gene’s fitness in that very particular kind of environment. If you want to know the overall fitness of the “A” allele, you add up the fitnesses in each set of specialized, detailed environments and weight them according to the frequency of that environment.