At 12:46 PM 1/18/2008, you wrote:
>I am certain there are several persons on this list that can add to our
>understanding of whether it is reasonable to comment on whether 50, 800, or
>any other number of breeder queens can be said to provide insufficient
>genetic diversity.  I'd like to hear them.

Most discussions on the number of required breeders center around maintaining enough sex alleles to have a minimum 85% brood viability Laidlaw & Page state that only 35-50 breeders are required to maintain the viability for 20 generations, 25 breeders if queens are replaced with their own daughters, and they suggest that even fewer would be required if brood viability was one of the criteria used for selection.  At first these number may seem terribly small, but it's implied that the breeders are not simply daughters of the same queen (as you might get buying 50 queens from a large queen producer), and all are mated with a mixed pool of drones.  So each queen may contribute 2 alleles of their own and 8-10 from the sperm they received with simple insemination.  For 35 queens that's like pulling 420 letters out of a hat hoping to get one copy of the alphabet.  You stand a good chance of having the full set of alleles (the alphabet) you started with in each generation.

Of course sex alleles aren't the whole picture and many closed breeding programs have brought in outside stock with care to obtain traits not already in the selected breeders.  I'm not sure how one would go about estimating the number of breeders needed for all traits needed now and for future needs, and no number could guarantee it.  So Laidlaw & Page suggests 50 is perfectly fine for a breeding program (it's actually at the upper limit), but I would expect they will bring in outside stock periodically.

-Tim  

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