Deleterious Gene?

Question

First of all what is a deleterious gene and how can anyone describe how evolution should deal with it. Can you als describe two situations in which deleterious gene are not removed from the population by natural selection. Any help is extreamly appreciated!

Answer 1

HCB has some good explainations.

Deleterious genes are genes that can cause developmental or disease problems at some point during the life of the organism.

They can be dominant or recessive.
Many are recessive, which means there is a single copy but a single copy of the good gene is all that's required for a healthy fully functioning organism.

However recessive genes stay in a population because the hetrozygous state is still fit, thus can't really be selected against.

As HCB stated,
Manifestation at an age past reproduction age is another reason why they are not selected against.

fruit flies, rodents and many other organisms can be selected in a lab to live longer. By letting them breed late in life.

Some believe humans, lifespan ~80 years, can be selected to live to 100. However it would be very difficult to perform in reality. The same may be true for Alzheimers.

I sometimes like to say:
Dumb, irresponsible people might have certain bad genes,
to rid our society of these people and genes is for the people to do something to get themselve's killed.
e.g. surfing on the roof of a moving Greyhound Bus going 80mph down the interstate and get decapitated by a bridge.
However they need to be killed before they have children, otherwise society will have his/her dumb son/daughter to deal with.
And let's hope the parent's of the decapitated boy decide not to have another child, to replace the one they lost, because he too might be mutant.
Maybe by then they would have had their tubes tied after seeing how their son turned out.

Another reason natural selection does not apply to humans in modern times is becuase almost all people can seek out medical help to extend their life.
Many still choose to have children.
Thus the mutation is never removed.

Another example is women who require cesarian sections to give birth. 60 years ago they and their baby would have died.

We can't exactly cull, euthanize, inprison or sterilize mutant or unwanted people. Although Hitler tried it.
I think it has something to do with ethics, religion, politics, civil rights etc.? LOL

Answer 2

Any allele that causes the death of an individual might be considered to be a deleterious gene. So, for example, the gene that when mutated causes Tay-Sachs disease is a deleterious gene. Simplistically, deleterious alleles should be eliminated by natural selection. However, the gene for sickle cell disease and the gene for cystic fibrosis have not been eliminated. We know that the sickle cell allele provides resistance to malaria, and there is some speculation about the possible benefit of the CF allele, too.

Another situation where a deleterious allele isn't eliminated by natural selection is then the gene causes a disease that develops after reproductive age. So, for example, the Huntington disease allele doesn't affect an individual until after they've passed reproductive age, and so can't be eliminated from the population by natural selection.

Answer 3

Hey, I'm aesthetic, not deleterious!!!