Evolution 101
This chapter considers some definitions and fundamental concepts of evolutionary biology, with a particular focus on the power of natural selection to improve the adaptation of individual plants and animals to their environment. It begins with a discussion of evolution by natural selection as a well-tested scientific theory, along with three conditions that must be met in the evolution of species by natural selection: first, there must be differences among individual members of the species; second, individuals must have some tendency to inherit the characteristics of their parents; and third, inherited differences must affect reproductive success. The chapter proceeds by assessing the implications of these changes within species for agriculture. It also gives an example of how populations evolve by natural selection and concludes with an analysis of the evolution of transfer RNA genes via less-fit intermediates.