If it's on this site, I can't find it...

 

I've heard that in order for a species to survive, it needs (I believe these were the numbers I heard, I don't swear to their correctness) 13 females and 7 males. (This obviously says that Adam & Eve and Noah's Arc didn't happen.) Can someone explain it to me, or point me to a place where it can be explained?

 

My guess was that (if 1male and 1female), that since everyone has the same genes, eveyone's features would be based off of two possible aspects. eg, mother's eyes or father's eyes. There are no other genetic possibilities.

 

It's probably over my head, but could someone try anyway?

 

Thanks much.

It doesn't have much to do with features really, but other alleles that are vital for survival of the species. As an example, each of our cells (humans and other mammals) has proteins called mhc molecules imbedded in the membranes. These MHC proteins present specific proteins from viruses that have invaded the cell by binding the proteins on the outside of the cell. Killer T cells then come along and recognize the virus protein and kill the cell before it can release more viruses.

 

Problem is that each type of MHC molecule can only present a certain amount of different kinds of proteins from viruses or other antigens. So while you may only have a small amount of different kinds of MHC molecules in your make up, the human population as a whole has hundreds. This insures that although some people will die when they are exposed to a new virus some members of the population will survive because the have the right complement of MHC molecules. There are other examples of the same concept.

It doesn't have much to do with features really' date=' but other alleles that are vital for survival of the species. As an example, each of our cells (humans and other mammals) has proteins called mhc molecules imbedded in the membranes. These MHC proteins present specific proteins from viruses that have invaded the cell by binding the proteins on the outside of the cell. Killer T cells then come along and recognize the virus protein and kill the cell before it can release more viruses.

 

Problem is that each type of MHC molecule can only present a certain amount of different kinds of proteins from viruses or other antigens. So while you may only have a small amount of different kinds of MHC molecules in your make up, the human population as a whole has hundreds. This insures that although some people will die when they are exposed to a new virus some members of the population will survive because the have the right complement of MHC molecules. There are other examples of the same concept.[/quote']

 

I think I understand (although my ENITRE knowledge of T-cells comes from the TV show "The Magic Schoolbus").

 

There would be some virus that Adam and Eve (example) would not be able to fend off, and as a result, none of their decendents would.. say it was the cold. Everyone who got the cold would die because they could't fight it and thus the species would end?

I think I understand (although my ENITRE knowledge of T-cells comes from the TV show "The Magic Schoolbus").

 

There would be some virus that Adam and Eve (example) would not be able to fend off' date=' and as a result, none of their decendents would.. say it was the cold. Everyone who got the cold would die because they could't fight it and thus the species would end?[/quote']

Yes, it also has to do with mutations and the ability to buffer them in the population with a healthy supply of alleles. Alot of mutations are recessive so that a healthy allele with be expressed instead of the mutation becuase you recieve two versions of each gene, one from mum and one from dad.

Thanks much!

Would that mean that polyploid organisms are more suited to surviving the effects of bottlenecks?

Would that mean that polyploid organisms are more suited to surviving the effects of bottlenecks?

Interesting question. My guess would be yes, for a healthy, viable allopolyploid at least.