1. Bellringer Evolution -What is it? -Is it a Fact?
-Do you agree with it? Why or Why Not?
-Is there evidence?
- What is natural selection?

2. Evolution: Darwin vs. Lamarck
Camouflage- makes it possible for animals to live in their natural habitat. Increases their survival.

3. Evolution: Darwin vs. Lamarck
Evolution: change over time; modern organisms descend from ancient organisms
Theory: Well-supported, testable explanation of phenomena
Don’t copy
Voyage of Beagle: Charles Darwin observed and collected fossils; proposed evolutionary hypothesis about way life changes
Patterns of Diversity: plants/animals well-
Suited to environment; variety of ways
to reproduce

4. Evolution: Darwin and Lamarck
Don’t copy
Galapagos Islands: islands west of South America; all have different climates

5. Evolution: Darwin vs. Lamarck
Darwin’s Thoughts:
He noticed that individual birds collected from one island looked different from birds collected from other islands
He wondered if animals living on different islands had once been members of the same species—meaning that separate species would have evolved from an original South American ancestor species after becoming isolated from one another.

6. Evolution: Darwin

7. Evolution: Lamarck
Jean Baptiste Lamarck: French naturalist noticed living things changed over time—all species desended from other species
Lamarck’s Theory: selective use/disuse of organs organisms acquired or lost traits during lifetime….traits passed to offspring…change over time (tendancy toward perfection)

8. Evolution: Lamarck
Animals continually change and acquire features that help them live more successfully in the environments (Bird’s Wings-inc. sizefly)
Alter size or shape of particular organs by using bodies in new way (no use of wingsdec. size, lose)
Ex. Weightlifting all lifetime, children big muscles too. Study hardchildren geniuses
Evaluating Lamarck’s & Darwin’s theory: No knowledge of how traits inherited—organism’s behavior has no effect on inheritable characteristics

10. Don’t Copy Evolution: Darwin
Darwin’s Theory:
Natural Variation: Differences among individuals of a species
Ex. Aquilegia flowers
Artificial Selection: Nature provides variation among different organisms, humans select
Ex. Largest hogs, fastest horses
*Natural Selection favors traits that benefit organism in environment Environment does “selective breeding”

11. Don’t Copy Evolution: Darwin
Fitness: ability to survive & reproduce in environment
Adaptation: inherited characteristics that increases organisms chance for survival
Survival of the Fittest (natural selection): Individuals better suited to environment, with high level of fitness, survive and reproduce successfully

13. Evolution: Darwin vs. Lamarck
Don’t Copy Natural Selection: struggle for existence. Species compete for food, living space…etc. (mutations & genetic recombination lead to this)
Evolution: Darwin vs. Lamarck
Don’t copy
*Over time, natural selection results in changes in the inherited characteristics of a population.
These changes increase a species fitness in its environment.

15. Natural Selection

16. Evolution of Populations
Chapter 16

17. Genes and Variation
Darwin and Mendel were unaware of each others work.
Neither could fully develop their theories
In the 1930’s scientists connected their ideas in one unifying theory

18. Variation and Gene Pools
Genetics variation is studied in populations
Population: a group of the same species that can interbreed.
A population shares a common group of alleles called a gene pool
a gene pool is all of the different genes that exist in a population
Sample Population
48 % heterozygous black
16% homozygous black
36% homozygous brown

19. Variation and Gene Pool, cont.
Frequency of alleles
Allele for brown fur
Allele for black fur
The relative frequency of an allele is the number of times that a gene occurs in a gene pool.
this is expressed as a percentage
(40% black, 60% brown)
Evolution is any change in the relative frequency in alleles in a population
So evolution would be in action if the relative frequency changed from 40% black to 30%

20. Sources of Variation Mutations: changes in the DNA sequence
caused by error in replication, radiation, chemicals in the environment
Only some mutations change the phenotype and affect fitness
Gene Shuffling: results from sexual reproduction
23 pairs of chromosomes can produce 8.4 million different gene combinations
Crossing over causes differences in genes.
Gene shuffling does not change the relative frequency of alleles in a population- you will still have the same number of alleles in the population, they are just recombined differently.

21. Single Gene vs. polygenic traits (pg 395-396)
The number of phenotypes produced for a single trait depends on how many genes control the trait.
Single Gene Trait (395): controlled by a single gene (2 alleles)
expressed in a bar graph
Polygenetic Trait (396): traits controlled by two or more genes – offers a great deal of variation
expressed in a bell shaped curve

22. Natural Selection on a Single Gene Trait
Natural Selection can act on a single gene trait that can change the allele frequency in a population and lead to evolution
Ex: lizards pg 397

23. Natural Selection on Polygenic Traits
Natural selection can affect the distribution of phenotypes in 3 ways
Stabilizing Selection
Disruptive Selection
Directional Selection

24. Stabilizing Selection
Individuals at the center have the greatest fitness
Pg 399

25. Disruptive Selection Both ends have greater fitness than the middle.
Page 399

26. Directional Selection
Individuals at one end have greater fitness than the middle or other end
Page 398

27. Genetic Drift Page 400
Genetic Drift: the random change in allele frequency.
Occurs in small populations that break away from a larger group
Caused by individuals entering and exiting the populations
this adjusts the allele frequencies in the gene pool and results in a change from the original group’s gene pool.
Ex: Founder Effect
when the allele frequency changes as a result of the migration of a small group

28. Evolution vs. Genetic Equilibrium
Hardy –Weinberg principle
States that the allele frequency will stay in genetic equilibrium (no evolution is occurring) if certain conditions are met
Random Mating
Large population ( so no genetic drift)
No movement in and out of the population
No mutation
No Natural Selection

29. Speciation Speciation: The formation of a new species
Species: a group of organisms that breed together and produce fertile offspring.
Reproductive Isolation: As new species evolve, populations become reproductively isolated from each other.

30. Reproductive isolation

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