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Very good idea. The only problem (not
necessarily a huge problem) is that both sexes have this feature. This is not
usual for sexual selection. The issue is why do just the Friarbirds have bald
heads. More to the point is that several species have partly bald heads. This
strongly suggests that it is not the now existing species but an ancestor of
several species, that evolved this feature and it still exists in their now
descendent species.
Philip
-----Original Message-----
From:
Alistair Stewart <>
To:
Birding Aus <>
Date:
Friday, 20 September 2002 15:24
Subject: [BIRDING-AUS] Noisy
Friarbird - WHY BARE HEADS AND BILL KNOBS?
G'day all
that are still reading this thread...
I'm surprised no one has
brought up sexual selection as a factor in its
evolution. Selection of
novel and extreme characters frequently occurs
in birds. Perhaps its
just a case of female friarbirds liking bald males
with big knobs, which
has been perpetuated over time. But there is most
likely a coaction of
factors that has led to its evolution, including a
possible fitness
advantage.
Another thing has come to mind, what if these characters
have evolved in
response to a now extinct species of plant, with
possibly a resinous or
sticky nectar...
Just throwing some ideas
around.
Al
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