A beginning

As a general, uncluttered by minute detail, overview, ogon, so far so good. Is there more?

You have a good handle on the basics, ogon. Be careful of this gene mixing thing. Genes do not blend. They are discrete "packets" with specific functions. It is the "suite" of genes acting in concert that exhibit specific traits.Eye color is always an excellent example.There is an Eye Color Gene. Actually, you have two of them. Let's say one is the Brown Eye Allele.(By the way, an allele is a gene for a specific trait. You have eye color genes. The one gene specific to color brown is the “brown eye allele” version of the eye color gene. You will often hear people speak of genetics and evolution in terms of allele frequency, i.e., the spread of a specific gene (allele/trait) within the larger population.)Anyway, you may also have a Blue Allele Eye Color Gene. Because of dominant/recessive mechanisms (usually) the brown eye allele will be expressed. The two do not blend together to give you muddy-blue eyes. The blue eye allele will just sorta sit there waiting to see if it gets to be passed on to the next generation where it may be paired up with another blue allele and thus get to be expressed in that individual. That’s kind of what most genes do is hang around to see if anyone will play with them.Now, in some instances the dominant/recessive mechanisms are not as strict and both alleles will be expressed. The result may appear to be a blending on the larger scale but is in fact the separate expression of each.ABE: And after a quick cup of coffee and thinking this thing over I want to emphasize what Subbie said in his response to you because his message is the very crux of the operation of evolution. Genes do not change to fit the environment. The frequency of those alleles that convey an advantage in a given environment tend to increase in a population. If the environment changes, the frequency of the various alleles will change over time. Through mutation, new alleles come into existence to be tested in a population. Over many hundreds of generations the alleles and their frequency will change so much that we may say speciation has occurred. This is evolution.Edited by AZPaul3, : Blame subie. It's his fault.Edited by AZPaul3, : Cant spel

Please excuse my humor. Genes really don't just lay around. Back to eye color, when the gametes (sex cells) are formed one allele ends up in each gamete. So you will have a gamete with the blue allele and another one with the brown allele.Now, to confuse matters, there are strands of our DNA (genes) that, at least for now, appear to be non-coding. The do not get expressed. You have probably heard of "junk DNA". These just get passed on, generation to generation, mutations and all without any noticable effect. In this case, changes or whole deletions can take place without affecting the population. I do not know of any examples to give you where any gene disappeard due to non-use, but others here may have some.An allele may not be expressed in a specific individual. But, may indeed be expressed in one's offspring. It all depends on which two gametes fuse to form the offspring.