Received: by alpheratz.cpm.aca.mmu.ac.uk id EAA12305 (8.6.9/5.3[ref firstname.lastname@example.org] for cpm.aca.mmu.ac.uk from email@example.com); Fri, 10 Aug 2001 04:06:49 +0100 From: <firstname.lastname@example.org> To: email@example.com Date: Thu, 9 Aug 2001 22:10:52 -0500 Content-type: text/plain; charset=ISO-8859-1 Content-transfer-encoding: Quoted-printable Subject: Re: Convergence Message-ID: <3B730A6C.28739.9CD038@localhost> In-reply-to: <3B728C91.B865E1D8@bioinf.man.ac.uk> X-mailer: Pegasus Mail for Win32 (v3.12c) Sender: firstname.lastname@example.org Precedence: bulk Reply-To: email@example.com
On 9 Aug 2001, at 14:13, Chris Taylor wrote:
Thanx for the info.; definitely a book worth reading!
> > Random mutation (within the same range of genetic possibilities),
> > followed by selection by similar environments for similar niches
> > should just about do it. Notice the word 'similar'; they are not
> > the same (or they could interbreed).
> There's another part to this story; as well as convergent evolution,
> there are 'morphogenetic attractors' which species are morphologically
> drawn to. This covers all the stuff that convergent evolution can't
> get. Brian Goodwin (inter alia) did some good stuff on these
> morphogenetic constraints (although I don't agree that his work
> 'challenges' Darwinism - just dust cover blag methinks). To summarise
> - there are some aspects of the physical world that affect the paths
> open to evolution; stuff like how many peaks and troughs of a
> concentration 'wave' of some molecule can you get along a body axis or
> around the circimference of a structure (Turing-style) - e.g. some
> animals are spotted, but the tails are ringed, because you can't set
> up complex enough concentration gradients in such a narrow structure.
> Or the Fibonacci sequence of side branch (etc.) angles on plants would
> be another.
> Additionally, for the tree with similar leaves, this could
> also/alternatively be a side effect of one or more traits of the
> organism that *are* truly evolutionarily convergent (answering the
> same question with the 'obvious' answer); this is known as pleiotropy
> (for the non-biologists here who may not have heard the word, its the
> situation where genes affect multiple traits, necessitating
> We don't need no hoodoo here. We just have to look hard for a good
> explanation, rather than running for the nearest shaman.
> Chris Taylor (firstname.lastname@example.org)
> http://bioinf.man.ac.uk/ »people»chris
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===============================This was distributed via the memetics list associated with the
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