Reproduction question

[greenbtree]

So, this has been bugging me from the first bee book I read.  With most critters, if they can reproduce at all without fertilization, and you are looking at a male/female system, an unfertilized egg that develops into offspring somehow is always female.  Because you need the y chromosome from the male.  Thus females are XX and can only make more XX and males are XY and can throw either the X or the Y.  So why do female worker bees when they lay viable eggs at all, only produce drones/males?

JC

[LoriMNnice]

 Bees are Haplodiploidy the females have two copies of each chromosome, but males have just one copy. To read more you can go here http://beespotter.mste.illinois.edu/topics/genome/

[FRAMEshift]

X and Y chromosomes are a mammal thing.   In eusocial insects like bees and ants, the queen lays fertilized eggs which develop into females or unfertilized eggs which become drones.  The most interesting part of this is that the unfertilized egg DNA is haploid and is therefore an exact copy of the contents of the queen DNA (or rather half of the queens DNA).  This still undergoes recombination so the genes may not be in the same order, but aside from a mutation, the drone will have the same genes as the queen.  

If you wanted to compare a drones DNA to a human situation, the drone is a recombined half-copy of the parent.  That is what sperm is in humans.  So just think of drones as flying sperm.   :-D

If you want to go a level deeper, there are 19 sex alleles in bees.  There must be two different ones to make a female.  One comes from the queen and one comes from another queen (via her flying sperm).  If the two halves are the same (as in a queen that mated with her own offspring drone) the result will be male.

Here is a good reference on bee genetics. http://www.glenn-apiaries.com/genetic_aspects_queen_production_1.html

[greenbtree]

Thanks a bunch!!!  It was the "different from other insects" that was really throwing me.

J.C.

[BlueBee]

We're talking bees here, right?  Is anything ever written in stone when it comes to bees?

Turns out the cape bee (Apis mellifera capensis) worker bees can lay diploid female brood.  They take out African bee colonies in this fashion.  http://en.wikipedia.org/wiki/Apis_mellifera_capensis

[greenbtree]

Sounds like the Cape bee is the Cuckoo of the bee world.

JC

[Michael Bush]

Haploids are all male because there is no different allele to match up to. Diploids are almost always female because most if not all the alleles are mated with one that is different. If all the pairs of alleles match (are the same as the one it is mated to) are all the same it will be a diploid male. Think of it as kind of like blood type, as in they are different proteins. So if you mate a A to an A you get a male. But if you mate an A to a B you get a female. Since there are several possible values and several alleles you only get the AA mate with an inbred queen. When the egg isn't fertilized you NEVER mate it to anything so you never get the AB situation required to make a female.

The only practical application of this is understanding why an inbred queen has peppershot brood patterns...

Otherwise you can just assume haploid=male and diploid=female.