[xmission]

Whether by mutation or any other cause if changes occur it is evolution.

My understanding is that evolution is:

a:Change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of new species.
b:The historical development of a related group of organisms; phylogeny.

Why would a change of eye color, hair color, etc qualify as evolution, especially when it could simply not be a dominent trait in the next generation, and fail to appear again?

[jec41]

Why would a change of eye color, hair color, etc qualify as evolution, especially when it could simply not be a dominent trait in the next generation, and fail to appear again?

You answered your own question.
a:Change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of new species.

It is change. There are 6.7 people on earth and no two are alike. They are short, tall, heavy, thin, white, black, yellow, of different hair composition and various other differences. It is the change in genetic composition that causes the difference. Without change everyone would be a perfect clone. There is a slight change with every reproduction. If a trait does not appear in the next generation it is change. If it appears in later generations it is still change.

[b_sharp]

Your answer is in the definitions you posted.

"a:Change in the genetic composition of a population during successive generations,

Evolution applies to the population rather than an individual. A specific allele needs to become fixed or at least on its way to becoming fixed before the population is considered to be evolving. There is an equation called the Hardy-Weinberg Equation that enables us to determine if a population is evolving (they always are) and how fast.