1. Section 1: Darwin’s Theory
What important observations did Darwin make on his voyage?
How did Darwin account for the diversity of species and the differences between similar species?
How does natural selection lead to evolution?

2. Darwin’s Voyage
Charles Darwin sailed on the HMS Beagle, from England to the Galápagos Islands and back, for 5 years starting in 1831.

3. Galápagos Islands Located 525 miles west of Ecuador.
Was visited by Darwin in 1835.

4. Galápagos Finches
Darwin noticed that on each island, the finches had adapted to the local environment.
Adaptation: a trait that helps an organism survive and reproduce in its environment

5. Galápagos Finches

6. 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.

7. 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.

8. 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.

9. Factors that Affect Natural Selection
Overproduction
Animals (including humans), plants, and other organisms tend to produce too many offspring, and there may not be enough food, water, or shelter to protect them all.

10. Factors that Affect Natural Selection
Variation
Members of the same species differ from one another in many of their traits
Example: You may be faster than your sibling, but your sibling may be taller, or have a better immune system, or have better reflexes.

11. Factors that Affect Natural Selection
Competition
All living things struggle to survive. Sometimes they compete for more food, or running away from a predator, or fighting off a disease.

12. Factors that Affect Natural Selection
Overproduction + Variation + Competition =
Natural Selection
The environment “selects” which members of a species lives long enough to have offspring. Some members have lots of offspring, others have few, and some have no offspring.
Over time, helpful traits (like speed, camouflage, and disease-resistance) will show up more often in a species. Eventually, most members will have this trait.

13. Adaptation: a trait that can help an organism survive
Things to Remember
Species: a group of similar organisms that can mate with each other and produce offspring
Overproduction: species creating more offspring than can possibly survive
Adaptation: a trait that can help an organism survive

14. Section 2: Evidence of Evolution
What evidence supports the theory of evolution?
How do fossils form?
What do scientists learn from fossils?

15. Homologous Structures
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.

16. Similarities in Early Development

17. Similarities in DNA and Protein

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

19. Types of Fossils
Molds and Casts: Most common fossil; organism dies and gets buried in sediment, creating a mold; more sediment later fills in this mold to create a cast

20. Types of Fossils
Petrified: rock minerals replace parts of the organism, turning the fossil into a hard, rock-like state

21. Types of Fossils
Trace: evidence of activity, such as footprints or cave paintings

22. Types of Fossils
Preserved Remains: organism trapped in amber, tar or ice; produces the best fossils

23. 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?

24. Evolution in Progress
There are over 150 major breeds of dogs and hundreds of other cross-breeds. All of these dog breeds (and wolves) came from the same ancestral animal

25. Kaibab and Abert’s Squirrels
These two kinds of squirrels have been isolated from one another for a long time. Eventually this isolation may result in two different species.
Kaibab Squirrel
Abert’s Squirrel

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

27. Extinction of Species
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.
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Woolly Mammoth
Baiji River Dolphin
Thylacine

28. Things to Remember
Extinct: no more members of a particular species exist; occurs when a species does not have the right adaptations to survive and reproduce

29. End of Section: Evolution of Species

30. Section 4: Classifying Organisms
Why do biologists organize living things into groups?
What do the levels of classification indicate about the relationship between organisms?
What characteristics are used to classify organisms into domains and kingdoms?

31. Classification through Names
Kingdom: Animalia Animalia Phylum: Chordata Chordata
Class: Mammalia Mammalia
Order: Primates Carnivora Family: Hominidae Felidae Genus: Homo Felis Species: H. sapiens F. domesticus

32. Classification through Names
Kingdom: Animalia Animalia Phylum: Chordata Chordata
Class: Mammalia Mammalia
Order: Carnivora Carnivora Family: Felidae Felidae Genus: Felis Felis Species: F. domesticus F. chaus

33. Three Domains of Life
In the three-domain system of classifications, all known organisms belong to one of three domains–Bacteria, Archaea, or Eukarya.
Bacteria Archaea Eukarya
Protists
Fungi
Plants
Animals

34. Levels of Classification
As you move down the levels of classification, the number of organisms decreases. The organisms at lower levels share more characteristics with each other.

35. End of Section: Classifying Organisms

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

37. A Branching Tree
Branching trees such as this show relationships between groups of organisms. It also shows the order in which specific characteristics may have evolved.

38. Shared Derived Characteristics
A branching tree diagram shows evolutionary relationships by grouping organisms according to shared derived characteristics.
Reptiles
Amphibians
Fishes
Egg with shell
Invertebrates
Four limbs
Backbone
Ancestor of animals

39. End of Section: Branching Trees