I hope its OK for me to butt into this thread with a stupid question. Its
on the sexual selection for a plumage feature. If both sexes start out
with the sexy plumage feature, as someone - I believe David Wright -
suggested might easily happen - it seems like a lot of good mating time
would be wasted by females being attracted to females with the feature
and males to males. How is this avoided?


Harriet Whitehead
Anthropology WSU

On Fri, 28 Apr 1995, Alvaro Patricio Jaramillo wrote:

> Tweeters,
>
> I think it was David Wright who asked if a feature could be caused by
> sexual selection if it was present on both sexes, I hope I have the
> question correct as I accidentally erased the message. My personal answer
> would be yes. Characters will be sexually selected if they improve the
> reproductive success of the carrier, when compared to individuals that
> don't have the character. Male and female choice for the same character
> can be operating at the same time, but likely with different strength,
> and this may reach the same equilibrium point (balancing costs and
> benefits of the character) for both sexes. So bright monomorphic plumages
> can evolve from a mix of male and female choice, that may be acting
> somewhat independently from each other. Slight dimorphism results when
> the cost/benefit tradeoff reaches a different equilibrium point than the
> males, likely because the benefits for having that plumage are not all
> that high for the females of that particular population, this may happen
> by females losing or gaining plumage brightness from the ancestral
> population. I imagine that sexual dichromatism is much more fluid in its
> evolution, since it is only the expression of the genes that has to
> change, the genes are already there since the male has the bright
> plumage. The same would not apply to a feature that like wingbars which
> both sexes either have or don't, it is rare that one sex has wing bars
> and the other does not.
>
> Of course some of these patterns can be caused by genetic drift, but
> that's no fun ;)
>
> Al "foaming at the mouth adaptationist" Jaramillo
> Vancouver, B.C.
> jaramill at sfu.ca
>
>