Hi Dave, apologies, as I realize what I posted was a little confusing.

line breeding falls somewhere in between "inbreeding" (breeding close relatives...useful to fix a trait in a population but has all the downsides of inbreeding that we are aware of in humans and other organisms) and "outbreeding" (matings between unrelated individuals..usually to introduce new genetics/traits)....a middle ground of sorts.

my previous post was confusing...it read as if "grafting" and "line breeding" were opposites...they are really unrelated terms (grafting can be used for inbreeding, line breeding, or outbreeding).  i apologize for the confusion.

doing walk away splits (if the virgin mates in a different yard) is an easy way to do line breeding (assuming your yards/drone supply is not closely related or completely unrelated to the virgin queen).

you can, of course, do line breeding by grafting...but the tendency (a human one) is to pick your best 1 or 2 colonies (i'm basing this on smaller operations) and rear all your queens from them.  if you start out this way, it is difficult to keep this kind of program from turning into "inbreeding" very quickly (this is something you talked about in your original post).

most breeders i know have found a happy medium (which could probably be described as line breeding)...where they do use their best queens as breeders, but are also mating with drones from a number of different families (which are also constantly being selected), and measures are taken to prevent them from becoming too related.

all of this reflects what nature does....start with a diverse population and add some big stress (like a really tough winter).  the population drops to 5% of the original, and whatever traits are found in the surviving population become more "fixed" as the small population breeds within itself.  as the population grows (perhaps with some poor inbred traits, or perhaps an abundance of diploid drones), it contacts other populations (which are going through the same process), and "outbreeds"...the resulting offspring have "hybrid vigor", and the most successful survivors pass these new genes into their respective populations....until there is another great stress that wipes out some of the population, and the process starts over again.

kirk webster has just put up a website (i know....i was shocked as well) that is well worth reading through.  especially relevant here is:
http://kirkwebster.com/index.php/some-thoughts-on-breeding-bees-in-the-north

...this should give you lots to think about :)  ...but yes, your instinct is correct....just grafting from the best queens will lead to problems (and an imbalance of how bee genetics spread).

deknow

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