This preview shows page 1. Sign up to view the full content.
Unformatted text preview: lations, or both. A gene or a phenotypic trait is said to be polymorphic if there is more than one form of the gene or more than one phenotype for that character in a pop- ulation. In some cases nearly the entire population is characterized by one form of the gene or character, with rare exceptional individuals carrying an unusual variant. That extremely common form is called the wild type, in contrast to the rare mutants. In other cases two or more forms are common, and it is not possible to pick out one that is the wild type. Genetic variation that might be the basis for evolutionary change is ubiquitous. It is impossible in this text to provide an adequate picture of the immense richness of even simple genetic variation that exists in species. We can consider only a few examples of the different kinds to gain a sense of the genetic diversity within species. Each of these exam- ples can be multiplied many times over in other species and with other characters....
View Full Document
- Spring '08