Re: Question about avian sex chromosomes

[Nick Pharris <npharris@umich.edu>]

Quoting David Marjanovic <david.marjanovic@gmx.at>:

> > How do fish do being male and female without sex chromosomes?
>
> Now different organisms have
> different master switches. I guess birds have theirs on the female
> chromosome... which is called either W or Z, I forgot.

Male birds have two W chromosomes; females have a W and a Z.  As I understand
it, the "default" development pathway is female in birds as well.  The
difference is that a double dose of whatever it is on the W chromosome is
required to switch to the male developmental track.

Nick Pharris
Department of Linguistics
University of Michigan