1. 1 Review Define the terms genes pool and relative frequency Predict Suppose a dominant allele causes a plant disease that usually kills the plant before it can reproduce. Over time what would probably happen to the frequency of that allele in the population 2 Explain How does genetic recombination result in genetic variation Relate Cause and Effect Why does sexual reproduction provide more opportunities for genetic variation than asexual variation 3 Explanation Explain how mutations are important in the process of biological evolution

2. Ch 17 Evolution of Populations
17.1 Genes and Variation

3. Darwin developed his theory of evolution without knowing how heritable traits passed from one generation to the next or where heritable variation came from.

4. In genetic terms
Evolution is the change in allele frequency of a population over time.

5. Genotype and Phenotype in Evolution
Natural selection acts directly on phenotype, not genotype
Some individuals have phenotypes that are better suited to their environment than others, produce more offspring and pass on more copies of their genes to the next generation.

6. Gene Pool
All the genes, including all the different alleles for each gene that are present in a population.

7. Relative Frequency
Number of times a particular allele occurs in a gene pool, compared with the total number of times alleles for the same gene occurs.

8. Natural selection operates on individuals
Evolution operates on populations.

9. Sources of Genetic Variation
Mutation
Genetic recombination during sexual reproduction
Lateral gene transfer.

10. Mutations
Mutations that produce changes in phenotype may or may not affect fitness
Some lethal or lower fitness
Some beneficial and raise fitness
Only matter if they can be passed from generation to generation
Must occur in the germ line cells that produce either eggs or sperm.

11. Genetic Recombination in Sexual Reproduction
Most heritable differences are due to genetic recombination
We have 23 chromosomes
Number of combinations
223
8.4 million combinations of each sperm or egg.

12. Lateral Gene Transfer
Occurs when organisms pass genes from one individual to another that is not its offspring
Can be same or different species
Think bacteria.

13. Single-Gene Traits Trait controlled by only one gene
Just two or three distinct phenotypes
Most common form of the allele can be dominant or recessive.

14. Polygenic Traits Traits controlled by two or more genes
Each gene of a polygenic trait often has two or more alleles
Often has many possible genotypes and even more different phenotypes.