AGENDA Mar 23AGENDA Mar 23• Objective: Summarize Darwin’s findings and the

evidence that supports Evolution.

• 1. Chapter 15 TEST– Makeup Date for TEST – TUESDAY March 24

• 2. Homework– Chapter 16-1 and 16-2 Vocabulary List – DUE TOMORROW!!! – NO LATE WORK ACCEPTED!!!

• TUESDAY MARCH 24

Question of the Day Mar 24Question of the Day Mar 24

• Which is not true about a species?

• A. Members live in populations

• B. They cannot breed with one another

• C. They can breed between different populations.

• D. All members contribute to the species gene pool.

AGENDA Mar 24AGENDA Mar 24• Objective: Investigate how genetic variation is

responsible for natural selection.

• 1. Question of the DAY

• 2. Chapter 16-1 Genes and Variation3. Review and Homework– Chapter 16-1 and 16-2 Vocabulary List DUE– DUE NOW!!! NO LATE WORK ACCEPTED!!!

Chapter 16Chapter 16

Evolution of Evolution of

PopulationsPopulations

VOCABULARY LISTSVOCABULARY LISTS

• Take out your Vocabulary Lists.

• Refer to it as we explore this Chapter.

• You already have this Chapter’s vocabulary in your notes.

16-1: Genes and Variation16-1: Genes and Variation• natural selection relies on

variation

• What is the source of inheritable variation?

• Nature selects the successful ones

• Populations Change

Evolution as Genetic ChangeEvolution as Genetic Change• Populations are studied.

– collection of individuals of the same species in a given area

– share a gene pool

• relative frequency: number of times an allele occurs in a gene pool compared to other alleles

• What is the relative frequency of the purple allele?

Genetic Variation within a SpeciesGenetic Variation within a Species• What is a species?

• Group of similar organisms that breed with each other and produce viable offspring because they share the same gene pool

• How do mutations occur?

• Mistakes in replication, radiation, and chemicals

• What else provides genetic variation?

Genetic Variation within a SpeciesGenetic Variation within a Species• How many different combinations of genes

can be produced from homologous x-somes in a human?– 8.4 million

Single-gene traits and Polygenic traits

Single-gene and PolygenicSingle-gene and Polygenic

Question of the Day March 25Question of the Day March 25

• What type of curve is produced when measuring a range of phenotypes?

• Bell curve

• What kind of traits are they?

• Polygenic Traits

AGENDA Mar 25AGENDA Mar 25• Objective: Investigate how genetic variation is

responsible for natural selection.

• 1. Question of the DAY

• 2. Types of Selection Homework

• 3. Chapter 16-24. Review and Homework– TEST MONDAY MARCH 30

16-2: Evolution as Genetic Change16-2: Evolution as Genetic Change

• Consider a population of lizards…

• Normal skin = Brown• Mutations produce Red and Black skin

• Predict the number of red lizards after 30 generations if the environment the lizards live in is a desert.

• WHY?

Natural Selection on Polygenic Natural Selection on Polygenic TraitsTraits

• Directional Selection – individuals at one end of the curve have higher fitness than those in middle or at the end.

• Dotted line = Original distribution of individuals

Types of SelectionTypes of Selection

• Stabilizing Selection – Individuals near the center of the curve have higher fitness than any other individuals.

• Dotted line = Original

distribution of human

babies

Types of SelectionTypes of Selection

• Disruptive Selection – Individuals at upper and lower ends of curve have higher fitness than those in the middle.

• Dotted line = Original

distribution of

individuals

GENETIC DRIFTGENETIC DRIFT• What controls genetics and the passing down of genes?• PROBABILITY

• Genetic drift: random change in frequency of a gene Population ↓ Change ↑

• Founder effect – change in allele frequencies due to the migration of a small subgroup of individuals.

Hardy-Weinberg PrincipleHardy-Weinberg Principle• allele frequencies in a population remain constant unless a

factors changes them

• only applies during genetic equilibrium

• Conditions to maintain equilibrium• random mating • very large population• no movement into or out of the population• no mutations• no natural selection

QUESTION of the DAY Mar 18QUESTION of the DAY Mar 18• When average sized seeds become more scarce

but smaller and larger seeds are still available as food sources, the type of selection that represents this change is

• A. Directional• B. Disruptive• C. Stabilizing• D. Drifting

16-3: The Development of New Species16-3: The Development of New Species• speciation: process in which new

species evolve from old ones• niche: combination of an

organism’s profession and the place it lives

• no two species can occupy the same niche in the same location for a long period of time

• any species that occupies a vacant niche will better survive and potentially form a new species

How fit are you?How fit are you?

• For the next 30 minutes…

• You don’t have any friends!

• It’s SURVIVAL OF THE FITTEST!

AGENDA March 27AGENDA March 27• Objective: Investigate the forces

responsible for speciation.

• 1. Question of the Day

• 2. 16-3 – Speciation

• 3. REVIEW FOR TEST

• 4. Homework and Review– TEST ON MONDAY March 30

DO NOWDO NOW

• Take out your lab packets.

• Your answers will assist you throughout class today,

Process of SpeciationProcess of Speciation• How do new species form?

• When populations are separated

• 1. Unable to interbreed

• 2. Gene pools change

• Darwin’s finches

Mechanisms of Reproductive IsolationMechanisms of Reproductive Isolation

• Behavioral isolation

• Geographic isolation

• Temporal isolation

Speciation in Darwin’s FinchesSpeciation in Darwin’s Finches

• 1. Founders species – first finches arrive on Galapagos

• 2. Geographic isolation - Some finches migrate

• 3. Different Gene Pools on each island

• 4. Reproductive isolation – Different islands

• 5. Competition – Species compete on same island

• 6. Continued evolution – 13 different species

CHAPTER 16 TESTCHAPTER 16 TEST

• MONDAY MARCH 30

• Study Guides will count as extra credit.

• All questions must be answered!

Speciation and Adaptive RadiationSpeciation and Adaptive Radiation

• adaptive radiation: one species produces many species– also known as divergent

evolution

• convergent evolution: different species evolve to have similar appearances and behaviors

• analogous structures: structures similar in appearance and function but have different origins

Pace of EvolutionPace of Evolution• punctuated

equilibrium: involves long periods of stability that are interrupted by episodes of rapid change

• gradualism: evolution occurs slow and steady over a long period of time