> On Mar 27, 2018, at 8:11 AM, Charles Linder <[log in to unmask]> wrote:
> This statement surprised me!  I would ask,  can you define bottleneck in this situation?  How many of the different types?  Alleles?  Not sure how you define a bottle neck in bees?
> 
> If we all choose to watch say  Fox news,  does that mean we have a bottle neck of shows?  Or that we simply choose that channel?   It seems to me in this case we choose to accept  these queens  as the best for our needs,  not because we have no genetic choice,  but because we like the traits?

Charles, I think you are misunderstanding the issue of a genetic bottleneck.  The problem isn’t so much with the traits that bee breeders are directly selecting for and paying attention to.  It is more with the rest of the genome that they aren’t particularly paying attention to until some problem severe enough to notice, even if you aren’t looking for it, crops up.  By having so few breeding queens that are used to produce the next generation year after year you will loss alleles in genes all over the genome.    In many cases this will have no consequence because the various alleles didn’t have significantly different biologic function.  But in some cases it will have significant effect.  This is why the term inbreeding depression exists and is a real phenomenon.

I think various dog breeds are great examples of what happens with severe bottlenecking.  The basic reason that different dog breeds have different health problems is that the breeders were focused on breeding for specific traits and were using strong selection to get there quickly.  By doing so they tended to use very small numbers of breeders and as a result other problems were created due to diversity lost in other genes not related to the trait under selection.  I should point out that the problem can be further compounded if an allele under strong positive selection happens to occur in an individual near another gene that happens to have a deleterious allele - in such a case the “bad” allele at the other gene can hitchhike along with the allele under positive selection and become common in the later generations even though it is bad for the individuals who have it and was never directly selected for.  To understand this better a great resource is http://cidd.discoveryspace.ca/breeds/overview.html <http://cidd.discoveryspace.ca/breeds/overview.html> which provides incredibly comprehensive information on genetic abnormalities in various dog breeds, and a great example would be inherited deafness in dogs such as the dalmatian where strong selection occurred for coat and skin color.

Mark Salser
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