1. Introduction to Evolution
Pre-AP Biology

2. Bellwork
Ancestors of the polar bear had a brown coat but today they have a white coat. Why? What initiated the change?

3. Objectives
Explain how Lyell and Malthus contributed to Darwins Theory of Evolution.
Define descent with modification and natural selection

4. Key Terminology Inheritance of acquired characteristics
Descent with modification
Natural selection

5. Important Dates Darwin – published his theory of evolution 1859
Mendel –published that parents pass on their offspring discrete heritable factors 1866
Hershey and Chase Experiment – discovery DNA genetic material-1952
Watson and Crick discovery of DNA structure -1953

6. Jean Lamarck’s Ideas One of first to develop a theory of evolution
Reasoned that organisms must adapt to their environment
Inheritance of acquired characteristics
organisms develop certain characteristics during their lifetime and pass them on to their offspring.
Example: Giraffe’s long neck
due to stretching to reach leaves

7. Ideas from Geology
Charles Lyell-geologist-suggested Earth far older than originally thought. Evidence:
Slow and gradual geological processes occur over long periods of time cause enormous changes to Earth
Examples
building of mountains
creation of canyons

8. Malthus and Population Dynamics
Observed more babies born than people dying
Suggests human population growing at a rapid rate
Maintain this pace, eventually run out of food and living space

9. PROPERTY OF PIMA COUNTY JTED, 2010
Think-Pair-Share
How might Malthus ideas be applied to plants and animals?
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

10. Darwin influenced by Malthus ideas
Applied Malthus ideas to plant and animal populations
Plant and animal populations typically do not become overpopulated.
Ex. Orange trees
Suggests certain factors keep population in check
disease
availability of food and other resources

11. Charles Darwin Darwin took a voyage on the HMS Beagle in 1831
Purpose of voyage was to map the topography of South American coastline
As a naturalist, his job was to record and collect the plants and animals of South America
From these observations developed his theory of evolution which was published in “Origin of Species”
in 1859

12. Two key ideas published in the Origin of Species
Descent with modification
Natural Selection

13. Descent with modification
Originated from common ancestor
Descendants of that ancestor spread into various habitats and accumulated modifications
Modifications were adaptations that allowed them to live successfully in that environment
Occurred over millions of years
Descent with modification was driven by natural selection

14. Natural Selection Individuals better suited for the environment
Are more fit
Survive and successfully reproduce
Passing those desirable traits onto their offspring

15. Natural Selection requires several factors
Genetic variation within the population
Environmental selection pressures
Ability of the organism to reproduce

16. PROPERTY OF PIMA COUNTY JTED, 2010
Think-Pair-Share
Why is reproduction critical to natural selection and descent with modification?
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

17. Example: Darwin’s Finches

18. PROPERTY OF PIMA COUNTY JTED, 2010
Think-Pair-Share
Examining the picture of finches, what was the 1. genetic variation 2. environmental pressure
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

19. PROPERTY OF PIMA COUNTY JTED, 2010
Think-Pair-Share
Why is the statement “She has evolved into a fine pianist” not biologically accurate?
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

20. 2 Minute Summary
Over millions of years, the average length of the giraffes’ necks has increased. During the time that this change was taking place, food close to the ground became relatively scarce, but there were always plenty of leaves on the higher branches of trees. Provide the most likely explanation for the giraffes’ long neck a) according to Lamarck b) according to Darwin