On 16/04/2012 10:30 PM, Peter L Borst wrote:

 >If heterosis leads to robust progeny then there is strong pressure to 
maintain wide variation in a population, whereas if inbreeding leads to 
weakness, those individuals that have a propensity to inbreed, will tend 
to drop out of the population as a result of producing inviable offspring.

I am not sure of the point you are making.  Presumably we are talking 
about managed beehives?  It is reasonably common to line breed and then 
outcross for the production organism.  Beef cattle spring to mind.  And 
of course it was used by the Starline and Midnight breeder.  The trouble 
is it takes a fair amount of work and expertise.


 > We know that if a queen mates with a drone that is too closely 
related to her, she will produce diploid drones due to being homozygous 
for the sex allele. Conversely, colonies that are a composite of many 
diverse patrilines seem to be much more vigorous,

Not only vigorous in the hybrid vigour sense,  we know that much of the 
benefit of multiple mating is that it widens the genetic makeup of the 
total hive.

 > But then, you take a lineage out of this population and attempt to 
propagate it, and you have isolated it from the very conditions that led 
to the production of this trait.

If you find the trait useful you make sure it is maintained, we call it 
breeding.


 >Look at the tragic weaknesses in our various breeds of livestock, 
pets, etc. Why would bees be excepted from the rule that if you 
ruthlessly select for one or two traits,

I am not sure what weaknesses you have in mind.  The ones that I am 
familiar with were from selecting for non measurable and or non 
commercial traits.

Geoff Manning

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