This program introduces the topic of biology by looking at an important evolutionary force, natural selection, and how it has affected a species of fox living on islands off of the California coast. Next, the ultimate source of variation is examined as the hereditary material, DNA, is examined. Genes, alleles, and proteins are discussed. How the hereditary material is distributed to offspring is the focus of meiosis by which sex cells are formed. Mutations give rise to new variations on which natural selection can act upon.