1. DO NOW
Wednesday
March 26th, 2019
STANDARD

2. Mechanism of Evolution (day 2)
Describe the processes of genetic drift, gene flow, and non-random mating; and explain how they result in evolutionary change

3. Natural Selection: Evolution
Vocabulary Review:
Evolution: a change in a heritable trait in a population over time
Heritable: able to be passed from one generation to the next
Population: the total of all the organisms of the same species

4. Natural Selection Review
Natural selection: Organisms that are best adapted to an environment survive and reproduce more than others
one of the main methods by which evolution occurs
Requires 4 main principles:
1. Overproduction of Offspring
More offspring are born than can survive
2. Inherited Variation
Difference in phenotype of population
3. Struggle to Survive
Competition for resources cause by
Overpopulation
Environmental pressure
4. Differential Reproductive Success
Organisms with better adaptive trait will survive and pass on its genes.

5. Check for understanding #1 Answer at the bottom of your notes
In his book On the Origin of the Species, Charles Darwin described how species change over time. Which of the following is NOT part of his observations that describes the mechanisms of natural selection? 
A. Organisms produce more offspring than can survive.
B. Disease and natural disaster will limit population growth.
C. Species today descended with modifications from ancestral species.
D. Organisms with advantages will survive and reproduce.

6. Mechanisms of Evolution

7. Definition: Movement of alleles from one population to another
Gene Flow
Definition: Movement of alleles from one population to another
How it works: When animals migrate and breed in the new population the traits of both populations are passed on

8. Lots of gene flow results in: genetically Similar populations

9. Gene Flow
Limited gene flow results in: genetically Different populations that could evolve into different species

10. Definition: Changes in allele frequencies due to chance alone
Genetic Drift
Definition: Changes in allele frequencies due to chance alone
How it works: Some alleles may increase in frequency while others may decrease or become eliminated from the population.

11. Genetic Drift Which allele gets lost is due to random chance.
Over time, drift tends to reduce genetic variation through random loss of alleles.

12. Genetic Drift
Bottleneck effect: genetic drift that occurs after an event drastically reduces the size of a population

13. Genetic Drift
Founder Effect: genetic drift that occurs after a small number of individuals separate from the population and form a new population

14. Genetic Drift
Negative effects: population loses genetic variation, so they are less likely to be able to adapt to a changing environment

16. Sexual Selection
Definition: Process which certain traits increase mating success and become more common in the population

17. Sexual Selection
How it works: Females mate with males that display certain traits, so those traits get passed on to offspring

18. Upsetting Genetic Equilibrium
Natural selection is not the only way that allele frequencies can change from one generation to the next.
Gene Flow (migration) – Alleles move from one population to another
Genetic Drift – a random loss of alleles.
Mutation – a new mutation can add alleles.
Nonrandom mating – inbreeding increases the number of homozygous traits.
All of these will increase genetic variation

19. Breeding Bunnies

20. How many individuals are there? How many are homozygous dominant?
The shapes below represent alleles in a individuals. Blacks represent F and white represents f
How many individuals are there?
How many are homozygous dominant?
Homozygous recessive?
Heterozygous?
3. How many F alleles are there? How many f? F F F F F f f f F F F f f f f f 8 3 3 2 8 8

21. FF = 8
F = 25
Ff= 9
f = 25
ff= 8

22. FF = 10
F = 25
Ff= 5
f = 9
ff= 2

23. Check for Understanding #2 Answer at the bottom of your notes.
A small population of chimpanzees lives in a habitat that undergoes no changes for a long period. How will genetic drift probably affect this population?
It will accelerate the appearance of new traits.
It will promote the survival of chimpanzees with beneficial traits.
It will increase the number of alleles for specific traits.
It will reduce genetic diversity.

24. Check for Understanding #3 Answer at the bottom of your notes
The concept of gene flow is demonstrated when a cow is driven off from its herd, joins another herd, and reproduces. When the cow contributes to the gene pool of the new herd,
which of these most likely increases?
Natural selection
Genetic variation
Environmental fitness
Reproductive mutations

25. Check for Understanding #4 Answer at the bottom of your notes
Two populations of mice living in the same forest are separated by a large water-filled ditch. After a rainstorm, flooding brings several mice from one population to the other population. When the mice from the first population reproduce with members of the second population, which of the following will likely occur?
All the offspring will die as a result of reproductive mutations.
The offspring will be forced to leave the second population.
The offspring will be genetically identical to their parent from the first population.
The offspring in the second population will have greater genetic variety.

26. Check for Understanding #5 Answer at the bottom of your notes
Lord Howe Island is a volcanic island in the Tasman Sea that is about 11 km long and 2.8 km wide. The island has two species of palm trees, Howea forsteriana and the more abundant Howea belmoreana. The two species do not interbreed even when they grow very close to each other. Which evolutionary process fails to occur?
Genetic drift of Howea forsteriana
Natural selection of adaptive traits in both species
Gene flow between the two species
Mutations in Howea belmoreana