1. Chapter 16
Evolutionary Theory

2. Pre-class Question 5/21/09
Why were the beaks of the finches that Darwin observed on the Galapagos Islands different on different islands?
Homework (due Friday)
Active Reading “Developing a Theory”

3. A broad explanation that has been scientifically
Developing a Theory
Evolution is the process by which species change over time.
Charles Darwin was responsible for developing the modern theory of evolution
A broad explanation that has been scientifically
tested and supported

4. 3 Types of Selection Artificial Selection
Humans can choose what traits are favorable in a species and breed plants and animals to have these traits
Natural Selection
The process by which individuals that are better adapted to their environment survive and reproduce more successfully than those that are less adapted to do so.

5. 3 Types of Selection Continued
Sexual Selection
An evolutionary process by which a mate is chosen on the basis of a particular trait

6. It’s Who You Know and What They Know
Darwin came up with the theory of evolution based on his observations and those of others:
Lamarck
Observed that each organism is usually well adapted to its environment.
Malthus
In 1798,Malthus observed that human food supply was increasing at a slower pace than the human population and hypothesized that many humans would die off due to disease, war and famine.
Lyell
Geologist that though that processes such as erosion and the formation of fossils was gradual and constant.

7. Evolution by Natural Selection
Darwin’s theory predicts that over time, the number of individuals that carry advantageous traits will increase in a population
Step1 Overproduction
Every population is capable of producing more offspring than can possibly survive.
Step 2 Variation
Variation exists in every population in the form of inherited traits.
Step 3 Selection
Based on traits one individual is more likely to survive than another and reproduce.
Step 4 Adaptation
Over time, those traits that improve the survival and reproduction will become more common.

8. Pre-class Question 5/27
Why do you think that giraffes evolved to have long necks?
What is the selective pressure that caused this change to occur?
Hint: Selective pressure is any phenomena which alters the behavior and fitness of living organisms within a given environment.
Homework
Study for Chapter 16 Vocab Quiz (Friday, 5/29)

9. Darwin – The Origen of Species by Natural Selection
Darwin presents evidence of evolution from multiple fields of science, where some species of animals have common characteristics
The Fossil Record
The study of fossils or traces of living things from the past
Biogeography
The study of the location of organisms around the world.
Developmental Biology
The development of organisms from embryos
Anatomy
The study of bodily structure of animals
Biochemistry
The study of biomolecules such as amino acids and DNA

10. Evaluating Darwin’s Ideas – 3 major strengths
Evidence of evolution
A mechanism for evolution
Natural Selection
The recognition that variation is important
Prior to Darwin’s theory, species were classified by
Common appearance, and ignored variation which
Was a starting point for evolution

11. Evaluating Darwin’s Ideas – Weaknesses
Inherited variation was important to Darwin’s theory, but he did not have a clear idea of how traits were inherited. He did not have an understanding of genetics.
There was roughly 100 years between when Darwin published his theory and the structure of DNA was discovered.

12. Reading Selection: How Do Species Change Over Time?
Pre-Class 5/28
Take out yesterday’s activity
Reading Selection: How Do Species Change Over Time?
Homework
Study for tomorrow’s chapter 16 vocab quiz

13. Studying Evolution at all Scales
Change in the genes of a population
The formation of new species as a result of evolution
The appearance of new species over time

14. Microevolution vs. Macroevolution

15. Processes of Microevolution (5)
Natural Selection
Migration
Mate Choice
Can be random or through sexual selection
Mutation
The numbers and types of alleles can change from generation to generation although it is rare
Genetic Drift
Genetic drift affects genetic makeup of the population through an entirely random process..

16. Patterns of Macroevolution (6)
Covergent Evolution
When evolution is strongly directed by the environment, species living in a similar environment should evolve similar adaptations.
Coevolution
Species that share an environment can affect each others evolution. They develop adaptations to coexist

17. Patterns of Macroevolution Cont.
Adaptive Radiation
Species splint into two or more lines of descent
Extinction
Gradualism
Many small changes occur gradually over time
Punctuated Equilibrium
New species suddenly appear after some environmental change.

18. Gradualism vs. Punctuated Equilibrium