[FT]Population minimums

I was just having an Email discussion with Thomas Barclay, and Beth
Fulton, on the minimum (human) populations are possible for a viable
genepool.

With Beth's approval, I include it here for everyone:

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Actually I'm a biomathematician - best of both looney worlds ;)
Which reminds me, if you were the one who was asking about
population growth (I haven't read the list directly lately, but my
husband has been giving me running summaries), I'm sorry
I never got around to answering the call (I meant to, but I had
some major PhD stuff due).

>Ok...Here goes:  How small can a Human population be and still have a
viable
>genepool?
>
>I friends have told me they thought it was 5,000 or 3,000,000 peaple.
>
>Any help you could provide is appreaciated.

As far as I can remember for humans and based on other mammals
(something
I'm a lot more familiar with) 2000 - 5000 is probably about the smallest

naturally
functioning group you can get and still bounce back with much genetic
diversity.
Theoretically 1000 is do-able, but you're pushing it. Within the
literature
500
individuals has been recognised as the absolute minimum viable
population,
but they have to be VERY reproductively active and even then you're
usually
cactus (eventually).

There will be some founder effects even with a few thousand as a base
(look at
Iceland its one of the best existing examples), but not so many that the

population
is in that bad a shape. And not all founder effects are completely
disastrous
- e.g. cheetahs in Africa must have been reduced to really small numbers

sometime
in the past (I mean 1000s of years) as you can do skin grafts and organ
transplants
without causing immune reactions, yet they still seem healthy enough at
present.
So I'd say safe minimum is 4-5000, but 10000 would be better.

That help?

Cheers

Beth
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Thanks Beth!

Now I can get back to my Space colony project....

Donald Hosford