1. Changes over time Life originated from a single-celled organism.
Finding a fossils age helps scientists to construct an evolutionary timeline.

2. Three types of Structures
Homologous
Vestigial
Analogous

3. Homologous Structures
Traits are similar in different species because they share a common ancestor.

4. The Theory of Evolution
Variation, Adaptation, and Evolution

5. Evolution Learning Goals:
Relate variation and adaptation
Describe how fossils are used to study ancient-life
Analyze Darwin’s theory of evolution
Explain how scientists reconstruct history using fossils
Identify characteristics defining a species
Describe the principles of population genetics
Explain the effect of environmental change on populations

6. Variation in a Species
A species consists of organisms that mate with each other and that can produce healthy offspring.
Differences between individuals in a population is called variation.
Ex. Fur color in foxes.
Two things can cause variation: mutation and recombination
Mutations can be harmful, neutral or beneficial.

7. Causes of Variation
*Two things can cause variation: mutation and recombination
Mutations can be harmful, neutral or beneficial
Beneficial mutations increase the chances of an organism’s survival.

8. Adaptation
An adaptation is an inherited trait that increases a population’s chances of survival and reproduction in an environment.
Adaptations= advantages that help an organism survive.

9. Biodiversity
The many different types of organisms that make up a biologically diverse community.
During times of change, populations that are better able to adapt will survive.

10. Natural Selection’s 4 points:
Variation within populations- inherited through traits.
Some variations are favored- improves chances of survival
Not all young survive- few live to reproduce
Individuals that survive and reproduce are those with favorable traits

11. Fossils, a peek into the past
Fossils, or the remains of ancient organisms, help scientists learn about Earth’s history.

12. Changes in the Past
All life originated from a common single-celled organism.
Finding the age of fossils allows scientists to construct an evolutionary timeline.

13. 3 Types of structures Homologous Vestigial Analogous
Similar structures in different species
Unused structures that are reduced in size
Similar characteristics in different species
Share common ancestor
No common ancestor. Independent evolution!!!

14. Homologous Structures

15. Causes of Speciation
Geographic isolation- members become separated from the original population due to geographic barrier.
Examples: mountain range, river
** Reproductive isolation- populations cannot or will not be able to produce offspring.

16. Embryology
Animals at the developmental stage of life look similar, but they grow up looking different.
Page 385 dragonfly book picture

17. Origin of Species
Speciation- is the evolution of one or more species from a single ancestor species.

18. Mechanisms of Evolution
There are 3 types of evolution:
Divergent evolution
Convergent evolution
Coevolution

19. Divergent Evolution Once related populations evolve independently
Often happens because of geographic isolation
Ex. Polar Bear and Brown Bear

20. Convergent Evolution
Unrelated species have produced (analogous) similar adaptations to help these organisms live in similar environments.
Ex. African Serval cat and S.American Maned wolf (pg.242)

21. Coevolution
When two or more populations closely interact for a long period of time, they begin to adapt together.
Ex. Hummingbirds and flowers. (pg. 243)

22. Adaptive Radiation
Evolution of many different, diversely adapted, species from one ancestral species.
Ex. Galapagos finch (13 different species)

23. Speciation in Darwin’s Finches
Founders Arrive – birds arrive
Separation of Populations- isolated one bird type onto 2 island
Changes in Gene Pool – through natural selection, mutation, etc.
Reproductive Isolation – new birds don’t cross-breed
Ecological Competition – may lead to new bird
Continued Evolution – process continues