explain what mircoevoultion is? what are the threee ways variation occurs?

Microevoltion is simply a change in gene frequency within the population. Between one generation the next the frequency of gene pesticide resistance of population of crops pest increase. A change might come of because of natural selction favored the gene. Some nonrestiant genes mutated to the resistant version. There are three ways variation occurs when mutation alter the order bases of the nucleotides in DNA. Mutations are rare amd most mutations are harmful, but in some instances the new alles can be favored by natural selection. This can also happen during meiosis.
http://answers.yahoo.com/question/index?qid=20090920160125AA1tK3U