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Re: Inbreeding and accelarated evolution?



Brian Lauret wrote:
> 
> As you might have guessed from the subject, I've been wondering about how
> inbreeding might influence the evolution of organisms.
> 
> On one hand I think inbreeding might accelarate the evolution of new
> characters, as a mutated gene influencing,say, the occurence of
> paedomorphosis, becomes more and more dominant in every generation ( I
> guess).
> 
> On the other hand, I argumented against this very idea that inbreeding makes
> organisms more and more alike due to the small gene-pool,wich thus means
> that characters are less likely to change.
> 

Inbreeding isn't such a problem in populations that are genetically
robust. Every Wollomi pine alive today seems to be genetically identicle
(and extremely healthy). Fijians appear to have gone through a genetic
bottleneck in the past, the result being that they tend to have stronger
immune systems than other human groups. If the founding population is
relatively free of negative recessive characteristics, then it might
just get lucky.

However many organisms aren't this lucky. Inbreeding would probably do
more to exacerbate existing recessive genes in a population. In general,
large long-lived animals tend to suffer more from inbreeding than
smaller short-lived animals. A dozen rats could probably populate an
island indefinitely. A dozen elephants would die out in a few
generations.

Perhaps this was one of the causes of dinosaur (and other) extinction.
Small animals may have been better able to withstand inbreeding after a
global event - larger animals may not have been able to produce a viable
long-term population with reduced genetic diversity, even if they
managed to ride out the climatic problems.

-- 
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Dann Pigdon
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://heretichides.ravencommunity.net/
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