1. Microevolution

2. Bell work
Explain how the sequence of amino acids in a protein and homologous structures provide evidence of evolution.

3. Objectives Define population.
Contrast macroevolution and microevolution.
Explain Hardy Weinberg Equilibrium.
List Evolutionary Agents that cause allele frequencies to deviate from Hardy Weinberg Equilibrium.

4. Key Terminology Population Microevolution Macroevolution
Hardy-Weinberg Equilibrium
Gene Pool
Gene Flow
Species
Genetic Drift
Bottleneck Effect
Founder Effect
Sexual Selection
Intersexual selection
Intrasexual selection
Antibiotic Resistance

5. Microevolution Evolution on smallest scale
Definition: Change in the frequency of alleles within a population from generation to generation
Review: What is an allele?

6. How do the Peppered Moths
demonstrate Microevolution?

7. Comparison to Macroevolution
Definition: Macroevolution examines changes over Earth’s history from the time Earth was created until now
Microevolution –looks at changes of an organism from generation to generation

8. Key terms used in microevolution
Population
Group of individuals of the same species living at the same place and the same time.
Considered the smallest unit to evolve.
Biological species
Group of populations whose individuals have the potential to interbreed and produce fertile offspring

9. Key terms used in microevolution
Gene pool
All the alleles in all the individuals that make up a population

10. How evolution is measured in a population
Measure how the alleles change in a population across generations
Two alleles found in a population
Dominant allele=p
Recessive allele=q
p and q represent the frequency of allele
Frequency = total number of dominant (p) or recessive alleles (q) divided by the total number of individuals in the population.

11. Sample problem
In a population of 1000 guinea pigs, 600 have the dominant allele for rough coat and 400 have the recessive allele for smooth coat. Calculate p and q.

12. Answer to Sample Problem
p=.6, q=.4

13. PROPERTY OF PIMA COUNTY JTED, 2010
Think-Pair-Share
If evolution did not occur what would happen to the frequency of alleles over ten generations?
3. Think-pair-share
teacher presents a question
teacher gives wait time for student to form answer
teacher instructs students to share their answer with a partner
teacher calls on non-volunteers to share with the class
PROPERTY OF PIMA COUNTY JTED, 2010 3

14. Hardy Weinberg Equilibrium
States that the frequency of dominant and recessive alleles stays constant across generations.

15. Five conditions must be met to achieve Hardy Weinberg Equilibrium
Population is very large
Population is isolated – no individuals moving in or out
Mutations do not alter the gene pool
Mating is random
All individuals are equal in reproductive success; natural selection does not occur

16. Hardy Weinberg is not achieved in nature. Why do we care?
Provides a baseline so we can recognize when a population’s gene pool is changing
Evidence that microevolution is occurring

17. 3 Minute Paper
You have 3 minutes to explain Microevolution and how Hardy-Weinberg Equilibrium is used to study it.
Be ready to share.

18. Evolutionary Agents that alter Allele Frequency

19. Genetic Drift Occurs when population is small
In a small population, individuals that carry a particular allele have more offspring than other individuals.
Over time that allele becomes more common in the gene pool
Two types of genetic drift
Bottleneck effect
Founder effect

20. Bottleneck effect
Bottleneck effect – catastrophic event (earthquake, flood, fire) reduces population size
Reduced population size has different allele frequency than original population
Example
Bubonic Plague killed 1/3 of European population

21. Founder Effect
Colonization of new location by a small number of individuals with different allele frequency than original population.
Examples
Iguanas from South American mainland populating Galapagos Islands
Dutch Afrikaners of South Africa have high rate of Huntington’s Disease

22. PROPERTY OF PIMA COUNTY JTED, 2010
Think-Pair-Share
Why does reduction in population size increase the chances of genetic drift?
3. Think-pair-share
teacher presents a question
teacher gives wait time for student to form answer
teacher instructs students to share their answer with a partner
teacher calls on non-volunteers to share with the class
PROPERTY OF PIMA COUNTY JTED, 2010 3

23. Gene Flow
Gain or loss of alleles from a population by movement of individuals or gametes
Result of migration
Reduces genetic differences between populations compared to isolated populations

24. Example of how Gene Flow changes Allele Frequency

25. Mutation Random change in the DNA
Vital to evolution because the only mechanism that creates new alleles
Because mutation rates low, has little effect on Hardy Weinberg allele proportion

26. Non-random mating-sexual selection
Selection of mates other than by chance
Mating generally not random
attracted to particular phenotypic traits
Two types of sexual selection
Intrasexual selection: competition within same sex
Intersexual selection-attraction between opposite sex

27. Intrasexual Selection
males compete between themselves for female’s attention
Example: battle between two male elk for female attention

28. Intersexual Selection
Female’s attraction to male’s features.
Example: Female Peacock attracted to male’s peacock tail

29. PROPERTY OF PIMA COUNTY JTED, 2010
Think-Pair-Share
Explain why sexual selection is a form of natural selection.
3. Think-pair-share
teacher presents a question
teacher gives wait time for student to form answer
teacher instructs students to share their answer with a partner
teacher calls on non-volunteers to share with the class
PROPERTY OF PIMA COUNTY JTED, 2010 3

30. Natural Selection
For natural selection to occur the following conditions must be met
There must be genetic variation within population
Genetic Variation results in unequal reproductive success
Example antibiotic resistance in bacteria

31. PROPERTY OF PIMA COUNTY JTED, 2010
Think-Pair-Share
Explain why the following statement is incorrect: “Antibiotics have created resistant bacteria”
3. Think-pair-share
teacher presents a question
teacher gives wait time for student to form answer
teacher instructs students to share their answer with a partner
teacher calls on non-volunteers to share with the class
PROPERTY OF PIMA COUNTY JTED, 2010 3

32. Letter or Note to a Friend
Write a note to a absent classmate explaining how evolutionary agents cause allele frequencies to deviate from Hardy Weinberg Equilibrium
27. Letter or Note to a Friend
teacher instructs students to write a note to a friend or absent classmate explaining the learning
teacher uses think-pair-share or collects to review
PROPERTY OF PIMA COUNTY JTED, 2010 32