Question 1What is a homologous structure?

a.Similar structures that serve different functionsb.Similar structures that serve the same function c.A structure that is of no importanced.Different structures that serve the same function

Homologous Structures

Question 2What are examples of molecular biology as evidence for evolution?

a.DNA hybridizationb.Antigen-antibody relationshipsc.Amino acid sequencesd.All of the above

Question 3Which of the following statements supports Lamarck’s explanation for evolution?

a.If you need a certain trait, then you will acquire itb.If you acquire a certain trait, then you will pass it down to your offspringc.If you do not require a certain trait, then it will eventually disappeard.All of the above

Lamarck vs. Darwin-Wallace

Question 4What is artificial selection?

a.When individuals select particular organisms for breeding b.When the environment selects organisms for breedingc.A and Bd.None of the above

Artificial Selection

Question 5Darwin’s Theory of Natural Selection states that:

a.There is a struggle for existence within a populationb.Nature (environment) selects for the strongest and “fittest” individualsc.There is variation in the populationd.All of the above

Question 6Which of the following statements about fossils is FALSE:

a.A fossil’s age can be determined by radio-carbon datingb.The youngest fossils are on the bottom layerc.Examples of fossils include teeth, bones, feces, amber castsd.Archaeopteryx is an example of a transition fossil

Question 7Different variations of a trait are called:

a.Genesb.Allelesc.Chromosomesd.Chromatids

Mechanisms for Evolution

What drives evolution?

Genes within a PopulationGene pool – total of all the alleles within a population

Black moth: BB or BbWhite moth: bb

Allele frequency– proportion of a given allele in a population50% white alleles + 50% black alleles

It’s Activity Time!

Genetic Equilibrium(Hardy-Weinberg Equilibrium)Allele frequency will not change if:

1.Population is large2.Random mating occurs3.No mutations occur4.No migration occurs5.No natural selection occurs

Sources of Genetic Variation

- Mutations-Beneficial only

- Sexual reproduction

What if there is genetic change?

Microevolution - change in gene and allele frequencies within a population

Drivers of Microevolution:1.Genetic Drift2.Genetic Mutations3.Gene flow4.Sexual selection5.Natural selection

Random

Controlled

1. Small PopulationGenetic drift – inevitable events that change allele frequencies. Smaller populations see a greater effect

Small populations can be a result of droughts, diseases, natural disasters

Example: 1 in 5 frogs is yellow and 60% of population is killed

Population 1 Population 2

Genetic drift results in dramatic changes in smaller population

Bottleneck Effect

Severe event reduces population

Bottleneck Effect - Today

Northern Elephant Seal 1890s – 20 seals left due to overhunting

Founder Effect

Individuals leave population to establish new populationMemory trick: Founder effect –foundation of new population

2. Genetic Mutations

What is a mutation?

Beneficial mutation - a change that gives individual an advantage in the environment

Harmful mutation – puts the individual at a disadvantage in the environment

Which would be selected for in a population? Which would be selected against?

Is this mutation considered beneficial or harmful?

3. Gene flow (Migration)Gene flow – movement of individual (alleles) from one population to another

Population 1 Population 2

• In some species, females select mates based on physical appearance.

• Examples: bright colouration, elaborate tail

4. Sexual Selection

Physical Features• Males who possess physical features can defend

their territory against other males• The secure territory can attract the female and be

an area where mating takes place

Example: Two male hippos fighting over territory

How does sexual selection affect gene frequency in a

population?

5. Natural selection-“Survival of the Fittest”

-Individuals with more favourable traits survive and pass down traits to offspring

-Over time, population consists of individuals with the favourable trait. Others do not survive

KEY POINT: Nature (environment) controls selection

LOOK AT THE MOTHS BELOW AND PREDICT THE TYPE OF HABITAT THEY

WOULD LIVE IN

PEPPER MOTHSpre-industrialization

Which moth would be more fit? WHY???

PEPPER MOTHSpost-industrialization

Which moth would be more fit? WHY???

Is there 1 particular phenotype that will always be favoured within a population?

Think about this...

Stabilizing Selection• The most common phenotype in the population

favoured by the environment.

Directional Selection

• Environment favours an extreme variation of a trait

• Example: Birds prefer to eat blue butterflies. Therefore, butterflies with a purple colouration are favoured in the environment

Disruptive Selection• Individuals with

opposite extreme variations of traits are favoured

• Example: Birds prefer to eat medium-blue coloured butterflies. Therefore, white and purple butterflies are favoured

Sickle Cell Anemia-Controlled by 2 alleles

-Possible genotypes:AA – normal RBCAa – normal RBC that can

sickleaa – sickle celled RBC

Sickle Cell Anemia in Africa

Distribution of Malaria

Distribution of Sickle Cell Anemia

VS

Sickle Cell AnemiaWhich individuals are favoured in Africa?

Heterozygous individuals : Aa

Sickle-celled (Aa) are resistant to malaria. What type of selection is this?

Summary- Natural Selection operates on phenotype variation which is controlled by genotype

- When gene or allele frequency changes, evolution is taking place

Let’s See What You Learned!!!

Question 8This picture shows what type of selection?

a.Directional selectionb.Disruptive selectionc.Stabilizing selectiond.Sexual selection

Question 9 The founder effect is when:

a.Majority of individuals in a population die b.Individuals from a population leave to establish new populationsc.Individuals from a population join an existing populationd.Individuals from a population migrate from one population to another frequently

Question 10 Which of the following statements is false?

a.A beneficial mutation means that it will always be beneficial in any environmentb.A harmful mutation is generally selected against in a populationc.If a population is fairly large, then the allele frequency will remain constantd.Sexual selection can alter allele frequency