Let me put it another way: Do dominant genes ultimately lead to a phenotype that has the greatest chances of survival, or are these completely unrelated? Could a couple have 3 out of 4 children who are "weaker" than the fourth child?

 

Gib

Isn't white skin recessive?

Let me put it another way: Do dominant genes ultimately lead to a phenotype that has the greatest chances of survival, or are these completely unrelated?

It's largely unrelated. A dominant gene might be advantagous in one situation, the recessive might be better in another.

 

Isn't white skin recessive?

Not that I know of, unless you mean albinism.

I don't think dominant genes necessarily lead to more "fit" phenotypes. Polydactyly and several types of dwarfism result from dominant genes.

It would be good if all dominant genes were good for us, however that is not how it is.

 

a good example posted by Auburngirl05 about dwarfism, there are a few others too.

 

the answer to the original question is: sometimes depending on which gene you are referring to i.e. it changes from gene to gene (some yes, some no).

A good example of uncommon dominant genes is polydacylism, a genetic disorder where an infant is born with an extra finger. It's usually small and nonfunctioning, and is cut off at birth.

Why does this happen?

Mutations in the sex cell genes of animal cause physical characteristic to be passed on to their offspring. If it is beneficiall then they will be able to have more offspring and pass on the trait. If not, the organism will die off before it can reporduce. This is Darwin's theory of evolution (without the genetics part)

I seem to have heard that over time, intermarriage between fair skinned and dark skinned people will end up in dark skin (but of course this may be anecdotal and influenced more by environmental factors than pure genetics).

Children from a White skin person and Dark skin person usually end up with skin color somewhere in between. An instance of incomplete dominance?

It seems to be reasonably complicated, and not fully understood. Here's an article that gives an overview.

 

http://www.plosbiology.org/plosonline/?request=get-document&doi=10.1371%2Fjournal.pbio.0000027

Thanks for the article, it's very informative

I think you forgot about environmental factors as well, since going beach tanning can transform frankenstein into dave chappelle

Sure, but it doesn't effect there genetic codes (skin cancer aside)