The Genetics of EvolutionThe Genetics of Evolution

What is the relationship between What is the relationship between the genes of a population and the genes of a population and

evolution?evolution?

Standards:Standards:

BI7. a. Students know why natural selection acts on the phenotype rather than the genotype

of an organism. BI7. c. Students know new mutations are

constantly being generated in a gene pool. BI8. c. Students know the effects of genetic drift

on the diversity of organisms in a population.

Objectives:Objectives:

SWBAT… Explain that new mutations are constantly

being generated in a gene pool, and this can cause evolution.

Understand the decrease in genetic diversity in a population caused by genetic drift.

Where does the genetic variation Where does the genetic variation come from for evolution?come from for evolution?

Gene pool-combined alleles for all the Gene pool-combined alleles for all the individuals in a populationindividuals in a population

Genetic variation is stored in the gene poolGenetic variation is stored in the gene pool Alleles-different forms of trait (eye color)Alleles-different forms of trait (eye color) Allele frequency-measure of how common Allele frequency-measure of how common

an allele is in a populationan allele is in a population

What are the five factors that can What are the five factors that can cause evolution?cause evolution?

Genetic drift-allele frequencies can change due to Genetic drift-allele frequencies can change due to chance alonechance alone

Gene flow-the movement of alleles from one Gene flow-the movement of alleles from one population to another, changes allele frequencies population to another, changes allele frequencies in each pop. in each pop.

Mutation-can form new alleles, creates genetic Mutation-can form new alleles, creates genetic variation needed for evolutionvariation needed for evolution

Sexual selection-certain traits may improve mating Sexual selection-certain traits may improve mating successsuccess

Natural selection-certain traits can help survival, Natural selection-certain traits can help survival, these traits increase in frequency these traits increase in frequency

What is gene flow?What is gene flow?

Gene flow-movement of alleles from one Gene flow-movement of alleles from one population to anotherpopulation to another

Occurs when individuals of species move Occurs when individuals of species move between populationsbetween populations

Increases genetic variationIncreases genetic variation

What processes allow genetic drift to What processes allow genetic drift to take place?take place?

Genetic drift-changes in allele frequency Genetic drift-changes in allele frequency due to chance, decreases genetic diversitydue to chance, decreases genetic diversity

Bottleneck effect-GD that occurs after an Bottleneck effect-GD that occurs after an event greatly reduces the size of the event greatly reduces the size of the population. (overhunting)population. (overhunting)

Founder effect-GD that occurs after a small Founder effect-GD that occurs after a small number of individuals colonize a new area. number of individuals colonize a new area. (islands)(islands)

Genetic DriftGenetic Drift

Bottleneck Effect Polydactyl (Amish)Bottleneck Effect Polydactyl (Amish)

Summary QuestionsSummary Questions

What is the gene pool of a population?What is the gene pool of a population? Name two genetic factors that can cause Name two genetic factors that can cause

evolution.evolution. Does genetic drift decrease or increase Does genetic drift decrease or increase

genetic diversity?genetic diversity? What is the relationship between the genes What is the relationship between the genes

of a population and evolution?of a population and evolution? Explain standard 8c in your own words.Explain standard 8c in your own words.