Received: by alpheratz.cpm.aca.mmu.ac.uk id EAA12305 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-majordomo@mmu.ac.uk); Fri, 10 Aug 2001 04:06:49 +0100 From: <joedees@bellsouth.net> To: memetics@mmu.ac.uk 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: fmb-majordomo@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
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.
>
> http://www.amazon.co.uk/exec/obidos/ASIN/075380171X/o/qid=/sr=8-2/ref=
> sr_aps_b_1_2/202-1904542-6277442
>
> 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
> trade-offs).
>
> 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 (chris@bioinf.man.ac.uk)
> http://bioinf.man.ac.uk/ »people»chris
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> ===============================================================
> This was distributed via the memetics list associated with the
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> see: http://www.cpm.mmu.ac.uk/jom-emit
>
===============================This was distributed via the memetics list associated with the
Journal of Memetics - Evolutionary Models of Information Transmission
For information about the journal and the list (e.g. unsubscribing)
see: http://www.cpm.mmu.ac.uk/jom-emit
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