Replies

The smaller the number of individuals of a(n)y given type, the more unlikely would be eit(h)er change or survival.

And this is why I can't marry my cousin?

If 'good' traits are found in animals, attempts are made to breed those individuals that contain the traits: NOT to dilute them out again by breeding with the larger population.

This is done by CHOICE of the human doing the breeding:ID if you will.

The odds of a trait staying in the breed is enhanced by a SMALL number of units breeding: NOT a large amount of them.

You are confusing breeding with evolution. Breeding juggles existing dominant and recessive traits. Mutation introduces new traits.

However, in either case, the frequency of any trait is modified by selection, as with sickle cell trait, which is generally detrimental to a population, but has a net positive effect in areas infested with malaria.

Smaller populations often tend to amplify recessive traits that are detrimental. One copy of a recessive gene with a dominant gene may work fine, but a dual recessive
may express itself in a way that causes harm, decreases the efficiency of the organism, or not function at all.
The larger and more varied the gene pool, the better the odds are that these recessive traits won't combine.

However - some of these recessives supplied an advantage in survival at one time, but are now seen as a detriment in the modern world. Sickle-Cell anemia is one example. It protected from malaria so that trait was a great advantage when most people without the trait suffered/died as children/adolescents of malaria. I've seen some articles that suggest that some allergies and conditions are caused by the lack of once extremely common parasites that few (thankfully!) suffer from nowadays. (med/bio experts enlighten can correct me if wrong, please)

Why are there 'recessive' genes? Perhaps something/someone should weed out the bad copies?

As for not marring your cousin (euwww!), there are a few examples of royal families suffering from recessives; such as the house of Hanover's (?) hemophilia and the seemingly poor health of ancient Egyptian royals. (but that is more Blam's area)

As for the last comment: I have seen ads in the Newspaper..

"Puppies for Sale! - Part AKC (w/papers) Grand Champion Pointer - part sneaky *%&$% dog next door"

Sometimes, they decide on their own! (Snik!)