1. Change Over Time
7.3 Biological evolution accounts for the diversity of species developed through gradual processes over many generations. As a basis for understanding this concept:
a. Students know both genetic variation and environmental factors are causes of evolution and diversity of organisms.
b. Students know the reasoning used by Charles Darwin in reaching his conclusion that natural selection is the mechanism of evolution.
c. Students know how independent lines of evidence from geology, fossils, and comparative anatomy provide the bases for the theory of evolution.
d. Students know how to construct a simple branching diagram to classify living groups of organisms by shared derived characteristics and how to expand the diagram to include fossil organisms.
e. Students know that extinction of a species occurs when the environment changes and the adaptive characteristics of a species are insufficient for its survival.

2. Darwin
He discovered many fossils of extinct animals that were similar to modern species
Found many variations in plants and animals that led to the formations of his theories
Species- a group of organisms that resemble one another and are able to reproduce among themselves
Traits- genetic characteristics among similar organisms in a species that is passed from one generation to another
Offspring- child of a parent

3. Darwin’s Voyage
Charles Darwin sailed on the Beagle, from England to the Galápagos Islands.
Discovered many fossils of extinct animals that were similar to modern species
Found many variations in plants and animals that led to the formations of his theories

4. Overproduction and Variation
Natural selection is the process by which individuals who are better adapted to their environment are more likely to survive and reproduce than other members of the same species.
Variations- a difference in a characteristic or trait from one organism in a species to another in the same species

5. Competition and Selection
Variations among turtles make some of them better able to survive. Turtles that survive to become adults will be able to reproduce.
Survival of the fittest- theory of natural evolutionary processes that enables organisms that are best suited for their environment to survive
Evolution- overall change of a population’s gene pool over time through processes such as mutation and natural selection

6. Section 2: Evidence of Evolution

7. Forms of Evidence
Key concept: Similar body structures, patterns of early development, molecular structure, and fossils all provide evidence that organisms have changed over time.
Homologous structures- similar structures that related species have inherited from a common ancestor
Comparative anatomy- comparison of the structures of different organisms
The structure of the bones in a dolphin’s flipper, a bird’s wing, and a dog’s leg is similar. Homologous bones are shown in the same color.

8. Forms of Evidence
Early Development- how different species develop before birth
Scientists make inferences about relationships based on early development
Similarities in DNA and proteins- if two species have similar DNA and proteins, probably evolved from same ancestor

9. How Do Fossils Form?
Most fossils form when organisms that die become buried in sediments.

10. How Do Fossils Form?
Mold- hollow area in sediment in the shape of an organism or part of an organism
Cast- solid copy of the shape of an organism
Cast is the opposite of a mold
Petrified fossils- fossils in which minerals replace all or part of an organism
Trace fossils- fossils that provide evidence of the activities of ancient organisms, like footprints
Preserved remains- processes that preserves the remains of organisms with little or no change (tar, amber, and freezing

11. Learning From Fossils
The fossils record provides evidence about the history of life and past environments on Earth. In addition, scientists use fossils to study the rate at which evolution has occurred.

12. Learning From Fossils Paleontologists- scientists who study fossils
Fossils build a picture of Earth’s past environments
Fossils show how an environment has changed
Gradualism- proposes that evolution occurs slowly but steadily
Punctuated equilibria- accounts for gaps in the fossil record, periods of rapid change separated by long periods of little or no change

13. Section 3: Evolution of Species
What factors have contributed to the diversity of species?
How do new species form?
How do scientists infer evolutionary relationships among species?
What causes the extinction of species?

14. A Variety of Species
Key concept: Over time, different environments and genetic variation have produced, through natural selection, the variety of organisms that exist today.
Over millions of years, natural selection has produced different species with adaptations enabling them to live in specific habitats
habitats- specific environment that provides the things organisms need to live, grow, and reproduce

15. A Variety of Species
Genetic diversity- organisms within the same species are not identical
Some genetic diversity is because of mutations in DNA
Some genetic diversity is caused by rearrangement of genes during meiosis
Species that have a lot of variety adapt to changes in the environment
Most organism are genetically similar, they have a difficulty surviving environmental change

16. How Do New Species Form?
Key concept: A new species can form when a group of individuals remains isolated from the rest of its species long enough to evolve different traits.
Geographic Isolation is one of the main ways new species form
Sometimes a group is separated by a river, volcano, or mountain range
A wave can sweep members of a species out to sea and wash them up on an island

17. Kaibab and Abert’s Squirrels
Two kinds of squirrels isolated from one another by the Grand Canyon for a long time
This isolation may result in two different species
They belong to the same species but have different characteristics
*an example of Geographic Isolation

18. Inferring Species Relationships
Key concept: Scientists have combined the evidence from DNA, protein structure, fossils, early development, and body structure to determine the evolutionary relationship among species.
Compare genes to determine how closely related species are
More similar DNA is more closely related organisms are
In most cases evidence from DNA and protein structure confirm hypotheses on fossils, embryos and body structures

19. A Branching Tree
This branching tree shows how scientists now think that raccoons, lesser pandas, giant pandas, and bears are related.

20. Extinction of Species
Key concept: Extinction is caused by a change in species' environment. The members of a species may not have adaptations that allow them to survive and reproduce in the changed environment.
Extinct- no members of the species are still alive
Causes of extinction: disease, predators, humans, climate change
Not all climate changes cause extinction, some species have been able to adapt
Just like we saw in the Beak game, many organisms can survive but if the organism doesn’t get enough of what it needs it will not be able to reproduce and the species will become extinct.

21. Section 5: Branching Trees
How does a branching tree diagram show evolutionary relationships?

22. A Branching Tree
Branching Trees Diagram- show probable evolutionary relationships between groups of organisms. It also shows the order in which specific characteristics may have evolved.

23. Shared Derived Characteristics
Key concept: A branching tree diagram shows evolutionary relationships by grouping organisms according to shared derived characteristics.
Shared Derived Characteristics- homologous structures that are shared by all organisms in a group
Reptiles
Amphibians
Fishes
Egg with shell
Invertebrates
Four limbs
Backbone
Ancestor of animals

24. Constructing a Branching Tree
Organism with none of the characteristics are at the bottom
Next fork put group with one shared derived characteristics
Branch above that put organism with two shared derived characteristics
Continue until you end
with the organism that has
the most shared derived
characteristics

25. Reading a Branching Tree Diagram
1. Did crocodiles evolve from amphibians?
No they are on different branches of the branching tree.
2. Are rodents more closely related to primates or crocodiles?
Primates they are on a branch together with other.
3. Name a common ancestor between crocodiles and dinosaurs.
Two post-orbital fenestrae

26. Essay Question
You are a wild rabbit and your species currently lives in the desert. Most of the rabbits are brown but there are a few that are white. An asteroid hits the Earth and the environment you live in suddenly becomes very cold. It begins to snow leaving snow covering the ground. Will your species be able to adapt and live in the new environment? Explain and give details (what happens to white rabbits and brown rabbits).