There is a difference between a selective breeding program and a sustainable pool of alleles for breeding queens.

If you have a completely closed population, the number of sex alleles is known (but I can't find it easily at the moment; so let's go with 19, as stated was possible in the Bee Genetics and Breeding book).  Female workers result from mismatched sex alleles, and a nonviable male (drone) results from matching sex alleles.  If a breeding population is to have the best chance of minimal inbreeding, and  hence minimal nonviable larvae from eggs, the model from Laidlaw and Page points to low inbreeding with 50 colonies staying good at 40 generations.  35 colonies is good out to 20 generations.  Hmmm, page 339 in the book, 

This model assumed that the same queen mothers generated the drone sons and the virgin daughters.  If you don't do that, instead using a subpopulation of queen lines for the mothers of the virgins, then see Page, Laidlaw, Erickson, Closed population breeding 4. The distribution of sex alleles with topcrossing. If you need to look it up.  The model predicted low inbreeding again from 50 colonies, out to 40 generations, and low inbreeding with 35 out to 20 generations.

But wait!  In many areas, there are often a couple of colonies in any given square mile.  If the queen is flying out 2 miles, and drones fly out 1 mile, that is a 3 mile radius, and hence is 27 square miles.  That's 50 colonies right there, at 2 colonies per square mile.  

So.... if you want your drones to counter this influx of unknown genetics, well, maybe lots of drone comb in 20 colonies would at least even the odds.  As long as the other colonies are not often feral bees, with feral cavities, which will have more drones.  

As a partially foundationless beekeeper, I have seen easily 3 deep frames of drone comb in the equivalent of a double deep when the bees have their druthers on what kind of comb to draw out.  Foundation hives will probably not even have 1 full comb of drones, unless there is a lot of space at the bottom of the bottom deep and they don't scrape that comb.  

Keep in mind that looking to minimize inbreeding (mismatched alleles) is not the same as taking a few favored queens and spreading their genes.  Michael Palmer uses a number of select queens and all of the drones, with at least 100 colonies, and has not seen inbreeding (anymore; he said he has achieved it in the past, relayed at the "My Story" conference in 2018 in Medina, OH).  

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html