"Stanley"  wrote in
news:cn3dd4$d89$1{at}darwin.ediacara.org: 

> Quoting: "SRY (in primates) is not the only male-determining gene in
> mammals, or even the most common: most non-primate mammals use a
> different Y-chromosome gene, UBE1, for this purpose. Also, two species
> of "mole voles", Ellobius tancrei and E. lutescens, have lost the Y
> chromosome entirely. In one species, both sexes have unpaired X
> chromosomes; in the other, both females and males have XX.
> 
> The haploid-diploid system is found in Hymenoptera. Males are haploid;
> females are diploid. Thus, if a queen bee mates with one drone, her
> daughters share 3/4 of their genes with each other, not 1/2 as in the
> XY and WZ systems. This is believed to be significant for the
> development of eusociality, as it increases the significance of kin
> selection."(end quotes) 
> 
> Some questions:
 
> #3 Is it meaningful to speak about XX males? The size difference in
> humans between X and Y chromosomes is large but not as big as the size
> difference between Z and W chromosomes in birds. I have heard the Y
> chromosome described as a "degenerate X". I figure that the X
> chromosome (call it Xa) that makes a mole vole male in fact differs
> somewhat from the Xb that makes a female.

I'm only going to respond to this one, and I'm not really much of an 
expert, but in any case: While mammals for the most part use X and Y 
chromosomes to determine sex, this is not the case for many other classes. 
Many reptiles have their sex determined by temperature during egg 
development. Many fish can change sex based on environmental changes. AFAIK 
there are a number of animals in which the XX are male.  

Yours,

Bill Morse
---
þ RIMEGate(tm)/RGXPost V1.14 at BBSWORLD * Info{at}bbsworld.com

---
 * RIMEGate(tm)V10.2áÿ* RelayNet(tm) NNTP Gateway * MoonDog BBS
 * RgateImp.MoonDog.BBS at 11/15/04 5:55:42 AM