ABSTRACT
In this chapter we will deal mainly with gene mutations, their effects and connected matters. We will focus mostly on species in nature. Mutations lead to the alteration of a common phenotype or to variation and hence provide a subject for genetic research. Their importance for genetics and evolution of organisms in general is determined by their innovative role. Some organisms lend themselves to induction of mutations that can be detected easily and studied throughout reasonably short life cycles. Viruses, bacteria, fungi, fruit fl ies, some other invertebrates, certain plants and mice fi t these criteria. Thus, these organisms have been widely used to study mutation and mutagenesis, and through other studies they have also contributed to more general aspects of genetic knowledge.
