Susan:
As a general statement your comments are correct IMHO. Believing
something and proving it are not the same. With regard to Zebra Zinches,
the beauty of the study - no pun intended - was not that the elaborate
plumage markings were important to females, but that very fine deviations
from the "norm" were enough to discredit a male. In this particular case,
the negative impact was attributed to the asymmetry of the overall pattern
due to very minor changes in the banding patterns on individual feathers.
These banding patterns apparently can be altered during moulting if the
food intake of male varies significantly or the male is unhealthy
(parasites, etc.)
The exciting aspect of sexual selection to me, is not that it occur, but
why it occurs and currently there are a handful of competing ideas. For
example, take the stain bowerbird. We all know that the female is attract
to a bower in part because of the number of "blue" items placed nearby.
But, why the colour blue?
I enjoyed reading your response.
Dr. Wm. James Davis
e-mail
On Wed, 25 Mar 1998, Susan Myers wrote:
> > > close range while hidden in the swamp. I proposee that the male
> "intends"
> > > to display the fine markings under its tail. Why? In Zebra Finches the
> > > fine streaking on the breast is used by females to ascertain the health
> of
> > > the male - any disruption of the streaking pattern indicates a problem
> > > with feather development. The same process could apply to male Cetti
> > > Warblers.
> Hi Jim,
> On this topic, couldn't the same be said for most species? My thought would
> be that most bird species rely on visual signals to a large degree and that
> when a female is choosing a suitable mate she is particularly critical of
> the state of the male's plumage. I believe that it is thought that sexual
> selection plays a major role in the evolution of the ornate & bright
> plumage seen in many birds especially Birds of Paradise, pheasants, etc.
> and finches.The same would also apply to behaviour. I guess the plumage
> doesn't have to be ornate in order to conjecture that sexual selection may
> have influenced its evolution. Any comments?
> cheers,
> Susan
>
> Susan Myers
> phone: +61 3 9819 2539
> Email:Susan Myers
>
>
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