Question 1 What is a homologous structure? a.Similar structures that serve different functions b.Similar structures that serve the same function c.A structure that is of no importance d.Different structures that serve the same function

Homologous Structures

Question 2 What are examples of molecular biology as evidence for evolution? a.DNA hybridization b.Antigen-antibody relationships c.Amino acid sequences d.All of the above

Question 3 Which of the following statements supports Lamarck’s explanation for evolution? a.If you need a certain trait, then you will acquire it b.If you acquire a certain trait, then you will pass it down to your offspring c.If you do not require a certain trait, then it will eventually disappear d.All of the above

Lamarck vs. Darwin-Wallace

Question 4 What is artificial selection? a.When individuals select particular organisms for breeding b.When the environment selects organisms for breeding c.A and B d.None of the above

Artificial Selection

Question 5 Darwin’s Theory of Natural Selection states that: a.There is a struggle for existence within a population b.Nature (environment) selects for the strongest and “fittest” individuals c.There is variation in the population d.All of the above

Question 6 Which of the following statements about fossils is FALSE: a.A fossil’s age can be determined by radio-carbon dating b.The youngest fossils are on the bottom layer c.Examples of fossils include teeth, bones, feces, amber casts d.Archaeopteryx is an example of a transition fossil

Question 7 Different variations of a trait are called: a.Genes b.Alleles c.Chromosomes d.Chromatids

Mechanisms for Evolution What drives evolution?

Genes within a Population Gene 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 population 50% white alleles + 50% black alleles

It’s Activity Time!

Genetic Equilibrium (Hardy-Weinberg Equilibrium) Allele frequency will not change if: 1.Population is large 2.Random mating occurs 3.No mutations occur 4.No migration occurs 5.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 Drift 2.Genetic Mutations 3.Gene flow 4.Sexual selection 5.Natural selection Random Controlled

1. Small Population Genetic 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 1Population 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 population Memory 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 MOTHS pre-industrialization Which moth would be more fit? WHY???

PEPPER MOTHS post-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 RBC Aa – normal RBC that can sickle aa – sickle celled RBC

Sickle Cell Anemia in Africa Distribution of Malaria Distribution of Sickle Cell Anemia VS

Sickle Cell Anemia Which 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 8 This picture shows what type of selection? a.Directional selection b.Disruptive selection c.Stabilizing selection d.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 populations c.Individuals from a population join an existing population d.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 environment b.A harmful mutation is generally selected against in a population c.If a population is fairly large, then the allele frequency will remain constant d.Sexual selection can alter allele frequency