Received: by alpheratz.cpm.aca.mmu.ac.uk id EAA01448 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-majordomo@mmu.ac.uk); Fri, 19 Jan 2001 04:28:20 GMT Message-ID: <00de01c081cf$e11a8980$5eaefea9@cable.rcn.com> From: "Aaron Agassi" <agassi@erols.com> To: <memetics@mmu.ac.uk> References: <20010119035512.AAA4496@camailp.harvard.edu@[204.96.32.110]> Subject: Re: Now They're Singing a Different Song Date: Thu, 18 Jan 2001 23:25:39 -0500 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Sender: fmb-majordomo@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
Yes, but does this help to explain any Memetic equivalent?
----- Original Message -----
From: "Wade T.Smith" <wade_smith@harvard.edu>
To: "Memetics Discussion List" <memetics@mmu.ac.uk>
Sent: Thursday, January 18, 2001 10:56 PM
Subject: Fwd: Now They're Singing a Different Song
>
> ---------------- Begin Forwarded Message ----------------
>
> >From the BBC at:
>
> <http://news.bbc.co.uk/hi/english/sci/tech/newsid_1123000/1123973.stm>
>
> Songbird shows how evolution works
>
> By BBC News Online science editor Dr David Whitehouse
>
> Scientists may be witnessing one of the fundamental forces of evolution:
> the
> divergence of one species into two.
>
> One of the largest mysteries remaining in evolutionary biology is exactly
> how one species can gradually diverge into two
>
> Darren Irwin, UCSD
>
> It is the evidence that the originator of the theory of evolution, Charles
> Darwin, wanted to see but was never able to find.
>
> The new data comes from the songs of the greenish warbler, a bird that
> lives
> in the foothills of the Himalayas. Researchers have noticed that its song
> changes gradually throughout its territory.
>
> At the extreme ranges of its habitat, the greenish warbler will sing very
> different songs. This means that although the birds belong to the same
> species, they will not mate. And eventually, they will become two separate
> species
>
> One becomes two
>
> Biologists are saying that this shows how one species can become two, a
> process known as speciation.
>
> "One of the largest mysteries remaining in evolutionary biology is exactly
> how one species can gradually diverge into two," says Darren Irwin of the
> University of California, San Diego, US.
>
> The Himalayan warblers are an example of a rare condition known as a "ring
> species".
>
> "Ring species are unique because they present all levels of variation,
> from
> small differences between neighbouring populations to species-level
> differences in a single group of organisms," says Irwin.
>
> Defending territories
>
> The greenish warbler (Phylloscopus trochiloides) lives in a ring-shaped
> region around the Himalayas with gradually changing behavioural and
> genetic
> characteristics. The ring is broken in one place, in central Siberia,
> where
> two forms of the songbird exist.
>
> "This creates a paradox in which two co-existing forms of the songbird can
> be considered as two species and as a single species at the same time,"
> remarks Irwin.
>
> "Ring species are valuable because they can show all of the intermediate
> steps that occur during the divergence of one species into two. In the
> greenish warbler, as in most songbirds, males sing to attract mates and to
> defend territories.
>
> "The greenish warblers living in the Himalayas sing songs that are simple,
> short and repetitive. As you go north along the western side of Tibet,
> moving through central Asia, the songs become longer and more complex,"
> says
> Irwin.
>
> Recorded songs
>
> Irwin and his co-researchers publish their study of the bird in the
> journal
> Nature.
>
> In their paper, they describe how when recordings of songs were played to
> warblers which sang differently, the birds did not recognise them - and so
> would not breed.
>
> "The greenish warbler is the first case in which we can see all the steps
> that occurred in the behavioural divergence of two species from their
> common
> ancestor," says Irwin.
>
> "These results demonstrate how small evolutionary changes can lead to
> differences that cause reproductive isolation between species, just as
> Darwin envisioned."
>
>
> ----------------- End Forwarded Message -----------------
>
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