1. Charles Darwin and Evolution
Changes Over Time
Charles Darwin
and
Evolution

2. Charles Darwin

3. Charles Darwin
1831
When he was 22 years old he set sail aboard a British Naval Ship called the HMS Beagle.
5 year long trip around the world
He was a naturalist: a person who studies the natural world.
Darwin’s observations led him to develop one of the most important scientific theories of all time: the theory of evolution by natural selection.

4. Observations
During the voyage Darwin observed plants and animals he had never seen before.
He wondered why they were so different than the ones he had seen in England.
He was amazed by the tremendous diversity or variety of living things he saw.

5. Diversity
Today scientists know that living things are even more diverse than Darwin could ever have imagined.
Scientists have identified more than 1.7 million species of organisms on Earth.

6. Species
A species is a group of similar organisms that can mate with each other and produce fertile offspring.
What is the difference between a species and a breed?

7. South America

8. The Galapagos Islands

9. Finch Beaks

10. The Galapagos
Darwin observed some of the greatest diversity of life forms.
Giant tortoises, land tortoises
Seals
Lizards
Flightless birds
13 species of finches

11. Island differences
Darwin observed that you could determine what island a tortoise was from based on the shape of its shell.
Finches were noticeably different from one island to another. The most obvious difference was the various sizes and shapes of their beaks.
Adaptation: a trait that helps an organism survive and reproduce.
The beaks were an adaptation related to the foods the finches ate.

13. Evolution
Species gradually changed over many generations and became better adapted to the new conditions.
The gradual change in a species over time is called evolution.

14. Scientific Theory
Darwin’s ideas are often referred to as the theory of evolution.
A scientific theory is a well-tested concept that explains a wide range of observations.

15. Natural Selection
In 1858, Darwin and another British Biologist, Alfred Russel Wallace, proposed an explanation for how evolution occurs.
The next year Darwin published The Origin of the Species.
Natural selection is the process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species.

17. Factors that Affect Natural Selection
Overproduction
Competition
Variation

18. Overproduction
Most species produce far more offspring than can possibly survive.
Each year a female sea turtle lays over 100 eggs.
Why isn’t the sea full of sea turtles?

19. Competition
Since food and other resources are limited, the offspring must compete with each other to survive.
Only a few turtles will survive long enough to reproduce.

20. Variations
A difference between individuals of the same species is called a variation.
For example, some newly hatched turtles are able to swim faster than other turtles.
Some variations make certain individuals better adapted to their environment. Those individuals are more likely to survive and reproduce.
Without variation a species can become extinct.
Extinct meaning no longer and living members of that species

21. Selection
Over a long period of time, natural selection can lead to evolution. Helpful variations gradually accumulate in a species, while unfavorable ones disappear.
lizard

22. Speed of evolution
Gradualism- Described as a slow ongoing process by which one species changes to a new species
Punctuated Equilibrium- One species suddenly changes to another.

23. What role do genes play in evolution?
Only traits that are controlled by genes can be acted on by natural selection
Elephant Evolution

24. Peppered Moth
The Industrial Revolution began in England in the late 1700s.
Smoke from the factories blackened the tree trunks of trees.
Light colored moths were no longer camouflaged.
What color was more suited for the new environment?

26. How do New Species Form? Geographic Isolation Continental Drift
A new species may form when a group of individuals remains separated from the rest of its species long enough to evolve different traits.
A group is separated from the rest of the species

27. Continental Drift

28. Pangea
Pangea

29. Examples of New species: 10,000 years to change
Kaibab squirrel/Abert’s squirrel
North American White Tailed Deer/Fire Island Deer

30. Kaibab Squirrel
Abert's Squirrel

31. Kaibab Squirrel
Abert’s Squirrel

32. Used to determine the evolutionary relationships among species
Supporting Evidence
Fossil Records
Embryology
Homologous structures
Vestigial structures
Fossils
Body structure
Early development
DNA
Protein structures

33. Fossil
A fossil is the preserved remains or traces of an organism that lived in the past.
A fossil can be formed from parts of live organisms, foot prints, or burrows left in mud.
Actual age of fossils is determined by radioactive dating

34. How do they form?
Most fossils form when organisms that die become buried in sediments.
Sediments are particles of soil and rock.
Over millions of years layers harden to become sedimentary rock.
Some remains get buried in the sediment and are actually changed into rock.
Fossils that form in this way are called petrified fossils. Minerals replace all or part of an organism

36. Preserved Remains Ice preservation Tar pit
Tree sap hardens to form amber.
Imprint fossils
Cast fossils
Mineralized fossils

37. What can fossils tell you? How do they form?
The Fossil Record
What can fossils tell you?
How do they form?

38. Branching Trees: Cladograms
A branching tree is a diagram that shows how scientists think different groups of organisms are related.

42. Embryology The study of embryos and their development
The similarities suggest an evolutionary relationship among all vertebrate species.

43. Homologous Structure Bird’s wing Dolphins flipper Dog’s leg
All of their bones are arranged in a similar pattern.
These similarities provide evidence that these organisms all evolved from a common ancestor.
Similar structures that related species have inherited from a common ancestor are known as homologous structures.

44. Vestigial Structures Structures that don’t seem to have a function.
Example: Manatees, snakes, and whales no longer have back legs, but, like all animals with legs, they still have pelvic bones.
Humans: appendix, tailbone, wisdom teeth, and goosebumps