Wings

[Pierre Zagatti]

Anne Kilmer wrote:
> 
>  snip

> Another factor that might be considered: jumping is sexy. When you
> consider natural selection, sometimes you fail to note that frivolous
> factor: attracting the other sex.
>         This is not always frivolous, when one gets down to first causes. The
> alkaloids that tempt the female Monarch to yield, will protect the eggs
> from ants. She presumably does not know, so we cannot attribute purpose
> to her in this selection. Where we leave it, applying only logic, is
> that those who made this choice had grandchildren.
> snip

Hi Anne,

The theory of sexual selection was considered by Darwin himself
as a part of natural selection theory. In fact, the evolution of 
male seducing characters is always balanced by their value in
terms of predation avoidance, food access and so on.
A classical example is given by the antlers of the giant deer
Megaceros, which became extinct when its antlers did not fit
anymore with a new environment. I guess
this example is historically wrong, but it gives a good
illustration of the phenomenon.
Good entomological examples are given by the androconia of 
male lepidoptera. When a species has developed huge, conspicuous
androconia, this is frequently associated with sequestration of
toxic substances and their accumulation in the androconia.
Thus these androconia share a seducing, intraspecific function,
and a defensive, interspecific function. This culminates in the
very toxic arctiids Creatonotos, with androconia (coremata)
five times longer than moth body when fully extended.
This the case in danaids too. Have a look at the page I'm
preparing for the monarch:
http://www.jouy.inra.fr/papillon/papilion/nymphali/texteng/d_plexip.htm
several bibliographic reviews are given on the page
(the butterfly pages are not on line yet, some data are still missing).

All the best,

-- 
Pierre ZAGATTI
INRA Unite de Phytopharmacie et Mediateurs Chimiques
78026 Versailles Cedex
FRANCE
Tel: (33) 1 30 83 31 18
e-mail zagatti at versailles.inra.fr
http://www.jouy.inra.fr/papillon/