Subject: evolution : Wide repertoire wins mates (fwd)
Date: Dec 4 11:41:46 2000
From: Deborah Wisti-Peterson - nyneve at u.washington.edu



hello tweets,

an interesting paper that you all might be interested in reading!

regards,

Deborah Wisti-Peterson, PhD Candidate nyneve at u.washington.edu
Department of Zoology, University of Washington, Seattle, Wash, USA
Visit me on the web: http://students.washington.edu/~nyneve/
Life is better when you are reading a good book -- Author Tim Green



---------- Forwarded message ----------
Date: Mon, 04 Dec 2000 10:30:23 -0800
Subject: evolution : Wide repertoire wins mates

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Great reed warblers: The lead singer always gets the chicks.
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Birds with the brightest prospects, like the devil, seem to have all
the best tunes. Female great reed warblers choose males who sing the
widest repertoire of songs because it shows they were well brought up,
new research suggests.
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Songs are learned at a vulnerable stage of fledgling development, so
Stephen Nowicki of Duke University, Durham, North Carolina, and his
colleagues predict, adult males with the most tunes were well fed as
youngsters - turning them into eligible bachelors.

Although biologists know that male birdsong attracts females, the
exact message it conveys is a mystery. "We just don't know how the
male bird song can mean anything to the female," Nowicki explains. He
now claims to have the first experimental data that can answer this
question.
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"A male's songs may be an honest indicator of how well he developed in
the face of nutritional or other stresses experienced early in life,"
he suggests. Hungry chicks, in other words, have more on their mind
than choir practice. And undernourished fledglings generally make
poorer fathers when they grow up.
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To test the idea, Nowicki's team recorded the songs of year-old great
reed warblers (Acrocephalus arundinaceus) at a site in Sweden; they
also weighed the birds and measured the lengths of particular feathers
- the longest of which are usually found on the strongest, fittest
birds.
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Warblers with the most warbles also had the longest feathers -
seemingly supporting Nowicki's idea. The researchers also found
evidence of a link between wide song repertoire and body mass; they
will report the results in the journal Proceedings of the Royal
Society of London[12]1.
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So, what do female warblers think when they encounter males with
limited songs? That they are being chatted up by real bird-brains,
Nowicki says. Limited song learning indicates poorer brain development
in general.
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"By assessing the output of song learning, the female may gain
accurate information about critical cognitive abilities such as
spatial navigation and memory," he says. These are important for
skills that every good warbler father needs: the ability to defend
territory, for example, avoid predators and find food. Males with a
one-track mind miss out.
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This argument provides "a convincing solution to the problem," says
Nigel Mann of the bird and mammal sound communication group at St
Andrews University, UK.
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"Other studies have shown that ability in tits to remember where food
stores are located correlates with the size of certain brain nuclei.
An interesting further development of the idea, " Mann continues,
"would be to look more directly for a connection between such aspects
of foraging, spatial memory and repertoire size."
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1. Nowicki, S., Hasselquist, D., Bensch, S. & Peters, S. Nestling
growth and song repertoire size in great reed warblers: evidence
for song learning as an indicator mechanism in mate choice.
[13]Proceedings of the Royal Society of London 267, 2419-2424
(2000).
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=A9 Macmillan Magazines Ltd 2000 - NATURE NEWS SERVICE
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_________________________________________________________________
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[14]Macmillan Magazines Nature =A9 Macmillan Publishers Ltd 2000 Reg.
No. 785998 England.
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References
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1. http://www.nature.com/
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