1. The document discusses several mechanisms by which genetic variation is introduced and maintained in populations, including mutation, genetic recombination, gene flow, and genetic drift. 2. Mutation occurs via point mutations which change single DNA bases, and frameshift mutations which insert or delete bases, altering the genetic reading frame. 3. Genetic recombination occurs during meiosis when homologous chromosomes exchange genetic material, resulting in offspring with new combinations of parental alleles. 4. Gene flow introduces new variation into a population through immigration, while emigration reduces variation. Genetic drift leads to chance changes in allele frequencies, especially in small populations.