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