From: Donald Hosford <hosford.donald@a...>
Date: Wed, 17 Feb 1999 22:16:41 -0500
Subject: [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: ------------------------------------------------------------ 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 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