Drone Cells ?

[drstitson]

Diploid drones

These are very interesting and very informative re. the sex determination process in bees. (DOI: My first PhD studies were in the Goodfellow lab in Cambridge where the mammalian sex determining gene, SRY, was identified).

The simple model we all know and love is that queens and workers are diploid (result of fertilised eggs) and drones are haploid (unfertilised eggs).

However - this is not simple like in mammals where no matter how many X chromosomes you have the presence of just 1 normal copy of SRY on the Y chromosome makes you male.

Using classical genetic techniques it was determined that Honey bees have >=19 alleles (variants) of the sex determining locus. In order to be female they need two different versions (ie be heterozygous) of the same locus. Normal drones develop because they can only have one copy and hence to all intents and purposes are homozygous.

If queen mates with a single related drone (sib or son) - there is a 50% chance that diploid eggs will contain 2 copies of same sex determining locus allele and are thus homozygous - this means that they are forced down male developmental route (just as XX mice given just a single copy of SRY become phenotypically male).

As occurs most other organisms, diploid drones (like triploid workers) are large and infertile as they have more copies of the genome then they should.

 

[drstitson]

diploid drones

Forgot to add at end - avoiding diploid drones is one of the reasons for polyandry (mating with multiple - 10-20 - males) and wide ranging mating flights in bees along with the obvious increasing of genetic diversity (gene pool) in general.

One might assume around 5-10% diploid drones in truly outbred queens (all 10-20 males unrelated to queen so have full mix of sex alleles) and 50% in truly inbred queens (mated solely to related drones).

It is of course therefore obvious that one can never have a queen that is truly homozygous at all loci as such fertilised eggs would by definition turn into diploid drones.

So perhaps those who are interested in generating "pure" AMM or Buckfast strains, or perhaps increasing stocks of Varroa resistant strains, should aim to produce breeding stock with either high numbers of diploid drones or evidence of their presence as indicated by patchy drone brood on drone comb (indicating culling by workers of diploids).

Perhaps people could submit pictures of their drone brood (maybe next year now) and we could estimate degree of inbreeding?

 

[oliver90owner]

obvious increasing of genetic diversity

Are we simply talking of genetic variation here? Or have you come round to accepting that biodiversity is not necessarily quite as you argued on 15 Aug in your post at 09:47 when you said:

Quote:Bio-diversity is not the same as genetic variation within a species. It is the variation of life forms within a given ecosystem, such as the many millions of distinct biological species present on earth.[/B]

Just checking, as we do need to be consistent in our opinions and postings or people may not be so accepting of your posts.

RAB

 

[drstitson]

Rab

I am steadfastly NOT using the term BIODIVERSITY.

I specifically used the term "genetic diversity" qualified with "gene pool"!!!

;-)



On a serious note: any thoughts on incidence of diploid drone brood in stock that you have experience of?

 

[winmag270]

watch it mate, she's young enough to be my Daughter, now where was i in 1976

was there any need to add a comment which could be mis-read with threatening overtones, to something meant "tongue in cheek"..?

 

[oliver90owner]

I am steadfastly NOT using the term BIODIVERSITY.

My apologies. You are correct.

I got this from a well respected source on the internet:

Biodiversity encompasses the diversity of all living things, from human beings to micro-organisms, the diversity of all the habitats in which they live and the genetic diversity of individuals within a species.

I emboldened the last bit of it. You will, no doubt, be telling me the Natural History Museum have got it wrong?

RAB

 

[drstitson]

Rab

These definitions being put about nowadays (for public/general consumption) have too much of a touchy-feely ring to them for my liking. Sort of broad brush catch all terms that whilst useful to help emphasise the importance of various points when arguing about the perilous state of the environment to stakeholders (another god awful term) etc. do not represent common/everyday usage in scientific circles.

I have been involved in molecular genetics for 24 years now. I've worked with Prof Sir Alec Jeffreys and in the Genetics Dept in Cambridge. I've worked with, listened to and talked to numerous population geneticists. Not once has the term Biodiversity been used. Genetic Diversity yes.