i'm open to learning more about this.

here's how one could create a bottleneck if they wanted to:

start with just one hive and build it up to a strong double deep and try to have a few drone frames. split the queen out of the hive and make a two frame nuc. let the hive raise 9 good queen cells, and make 9 more nucs up out of it, for a total of 10 hives deriving from that one queen. be sure and locate these far away from any other bees.

if the mating occurs mostly with the drones from the parent hive. all of the bees will be so inbred, or bottlenecked, that the diversity would be all but lost.

in this extreme, and anything that approximates it, you should get marked bottlenecking.

for most operations, especially those around forested areas, i think you would have to try awfully hard to achieve a bottleneck.