Hello All,
>     In combination, the three create a situation where one would expect
> inbreeding in bad years, and outbreeding in good years which allow distant
> assemblies to form.

The above may be true with a small apiary.  Very little inbreeding occurs
with large scale queen rearing and migratory beekeeping.  The best queens in
my opinion come from queen breeders which also run a large number of hives.
They pick their breeder queens each year out of a huge number of hives.  I
have had the best luck with production queens picked in this way.
Inbreeding can fix undesirable traits in your bees.
The constant *drift* of drones in migratory operations gives hives a mix to
help prevent inbreeding.  Drones being able all summer to go freely in and
out of any hive they choose keeps down inbreeding.  Even our II SMR queen
hives with only black carniolan drones have always carried a huge number of
Italian drones hanging around.  These are simply drifters which have taken
up residence.  Drifting drones in my opinion is natures way of keeping down
inbreeding. Also natures way of spreading varroa.  My production hives are
Italians but I find black drones as far away as 10 miles from my carniolan
yard. . I believe these have simply drifted from yard to yard as locations
are about 2-3 miles apart. What carefree spirits these drones are and what a
rude awakening for the drones come the first cold fall day.
Sincerely,
Bob Harrison
Odessa, Missouri