1. 16-1 Genes and Variation

2. Gene pool Combined genetic information of all the members of a particular population

3. Relative frequency Number of times an allele occurs in a gene pool compared with the number of times other alleles occur.

4. Single-gene trait Trait controlled by a single gene that has two alleles

5. Polygenic trait Trait controlled by two or more genes

6. Key Concept In genetic terms, evolution is any change in the relative frequency of alleles in a population.

7. Key Concept The two main sources of genetic variation are mutations and the genetic shuffling that results from sexual reproduction.

8. Key Concept The number of phenotypes produced for a given trait depends on how many genes control the trait.