Peter & Rosemary Grant, Darwin's Finches and Evolution

IIRC Faith's main article of faith is that all possible alleles are present in the parent population but certain combinations can only flower in the absence of the dominant mixture seen in the parent population.Thus a group that goes off by itself becomes susceptible to producing these repressed variants as they lose the oppressive traits.Which can then become reproductively incompatible with the parent population ... ?

A fair point, and I do have some reluctance to focus on top picks when any individual that succeeds in surviving to breed just once does pass on genes (albeit a lower frequency than those more successful).The point, I guess, is that in a large population with a predominantly stable ecology there is a "trendency" towards an optimal combination/s of available traits and that those that are better fit\suited to survive and breed can do so at the expense of those less fit\suited. In a social species memorizing things can help the group survive which then ensures that descendants survive.