Subject: Re: orioles/genetics
Date: May 3 14:57:24 1995
From: Alvaro Patricio Jaramillo - jaramill at

Teresa Michelsen wrote:

> Sex-Limited: This is the case that could fit house finches (and according
> to my reference, accounts for the male peacock plumage). In this case, all
> house finches have a gene somewhere for "basic" plumage, the brown streaky
> plumage that juveniles and females have. Both M and F birds have this when
> they are born. Somewhere else there is another plumage gene that both M and
> F birds also have, but which is only expressed in the presence of male
> hormones. So at some point in the male bird's life (bird puberty, if you
> will), genes on the W chromosomes get busy cranking out male hormones and
> the red plumage shows up in males, while the females stay brown. This
> second gene is further complicated by having both dominant and recessive
> traits (the red and gold varieties). As you can see, many bird species fit
> this pattern.

A nice example that fits this scenario is found in Ruffs. Dov Lank, a
researcher here at Simon Fraser University injects females with male
hormones before the moult and gets them to express a male-like plumage,
complete with the funky colours and the ruff. He is doing this to be able
to understand the genetics of the territorial versus satellite male
plumage/behaviour types. The non-territorial satellite males have white
ruffs and ear tufts.
The work is being done on a lab colony here at school.

Al Jaramillo
jaramill at
Vancouver, B.C.