Received: by alpheratz.cpm.aca.mmu.ac.uk id MAA07848 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-bounces@mmu.ac.uk); Mon, 27 Aug 2001 12:50:24 +0100 Message-ID: <2D1C159B783DD211808A006008062D310174604E@inchna.stir.ac.uk> From: Vincent Campbell <v.p.campbell@stir.ac.uk> To: "'memetics@mmu.ac.uk'" <memetics@mmu.ac.uk> Subject: RE: Dawkins & Convergent Evolution- the final word (?) Date: Mon, 27 Aug 2001 12:40:13 +0100 X-Mailer: Internet Mail Service (5.5.2650.21) Content-Type: text/plain X-Filter-Info: UoS MailScan 0.1 [D 1] Sender: fmb-bounces@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
<Dawkins does concede that evolutionary convergence is "vanishingly
> improbable" in the neo-Darwinian model. >
>
No, he doesn't. What he's saying is that the probability that two
organisms should follow exactly the same evolutionary steps- i.e. the exact
same genetic mutations and selections- is vanishingly small. That is NOT
what happens in convergent evolution (if it did happen it might be called
something like parallel evolution- two organisms developing in isolation
from each other and yet following exactly the same evolutionary
development). In convergent evolution what happens is that consonant
environmental pressures over a long period of time produce organisms that
may look superficially similar, and/or exhibit similar patterns of
behaviour, despite having followed DIFFERENT paths of evolutionary
development. Even without looking at their genes, the fact that they've
followed different paths is evident in their differences- the best
collective example being marsupials.
<As I stated before, there are numerous
> examples of convergence with no explanation according to natural
> selection,
> such as traits that come in handy in relation to a predator that's never
> existed in other locations where it crops up.>
>
Well, I'd like some examples here, since most that we know of
species moving from one environment to another is usually chaos as native
species are unable to deal with the intruders (again, Australasia with it's
cane toad and rabbit plagues etc. etc.).
Vincent
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