1. Chapter 15: Darwin’s Theory of Evolution
Evolution: change in a population over time (Long Periods of Time)
Charles Darwin

2. The Voyage - 1831 H.M.S. Beagle – The Ship
A voyage around the world – The Mission

3. What was Darwin’s job on this mission
What was Darwin’s job on this mission? Make observations & collect evidence
Darwin was very fascinated by the Land Tortoises, Marine Iguanas and the Finches of the Galapagos Island
Galapagos Video – Click on Tortoise

4. Blue Footed Boobies
Marine Iguanas
Frigatebird

5. All These Observations (3 Main Points):
Patterns of Diversity-He was puzzled by where different species lived and didn’t live.
Ex. Australia and Argentina are both grassland ecosystems, but had very different species.
2. Some living organisms and fossils he collected were very similar.

6. The Galápagos Islands, though close
together, had very different climates and
had organisms with
characteristics that
varied noticeably.
Pinta Island –Intermediate shell
Hood Island- Saddle back shell
Reasons for variations?
Isabela Island- Dome shaped shell

7. All great thinkers need inspiration……
James Hutton (1785) – Proposed that Earth was shaped by geological forces that took place over extremely long periods of time.
He estimated the Earth to be
millions of years old. He wrote the
"Theory of the Earth“.
Thomas Malthus (1798) – The human population was growing faster than the space and food needed to provide for it. Natural disasters and forces of nature would solve the problem.

8. Other good thinkers…
Jean-Baptiste Lamarck (1809) – One of first to propose a mechanism of how things change over time, and that all species were descended from other species. Common Descent
Lamarck's scientific theories were largely ignored or attacked during his lifetime; Lamarck never won the acceptance and esteem of his colleagues and he died in poverty and obscurity.

9. His Theory: By selective use or disuse of organs, organisms acquired or lost certain traits during their life time

10. Example:
A giraffe acquired its long neck because its ancestor stretched higher and higher into the trees to reach leaves, and that the animal’s increasingly lengthened neck was passed on to its offspring.

11. The Light Bulb Goes Off…
Charles Lyell (1833) – Wrote Principles of Geology, made Darwin ask himself:
“If the earth can change over time, then why can’t the things on it?”
“ It must have taken life
many, many years
to change.”

12. A Little Support for Natural Selection
Alfred Wallace (1858) – Writes to Darwin with his own findings supporting the idea of evolution by natural selection.

13. Darwin’s Theory
All these observations and influences led to a revolutionary theory about the way life changes over time.
What is a Theory? – well-supported testable explanation of phenomena that have occurred in the natural world
1859 Darwin published his book:
On the Origin of Species
“Life changes over time by the process of natural selection.”

14. The Theory
Organisms have a tendency toward overproduction (seeds, offspring) because not all organisms will survive.

15. Struggle for Existence
Members of each species compete regularly to obtain food, living space and other necessities of life.

16. The Theory
2. Variations exist in any population and some are inherited.

17. The Theory
3. Individuals better suited to their environment live longer and therefore produce more offspring than those less suited.

18. Survival of the “Fittest”
Fitness results from adaptations that give an organism advantages for survival. The most “fit” organisms will survive and reproduce; passing along the advantageous characteristics to their offspring. These changes are usually only be seen after many generations!

19. Types of Adaptations
Structural adaptations are traits that involve the physical structure of an organism such as the beaks of birds.
Physiological adaptations are traits that involve the functions of an organism such as having enzymes to digest food.
Behavioral adaptations are things organisms do to survive such as birds laying eggs in a nest instead of on the ground.

20. The Theory
4. The entire population will change as those better suited continue to reproduce, meaning the population becomes better adapted to its environment.

21. Descent with Modification
As organisms change over time; they become different, resulting in many varied species. This illustrates “common descent.” All living things have a common ancestor.

22. Patterns in Evolution Gradualism Punctuated Equilibrium
Change is slow and continual. Populations stay the
same then change
drastically.
ex) Mass Extinctions

23. Day Two: Natural Selection
Evidence to Support the Theory

24. Let’s Recap…The Theory
Organisms have a tendency toward overproduction (seeds, offspring) because not all organisms will survive.
Variations exist in any population and some are inherited.
Individuals better suited to their environment live longer and therefore produce more offspring than those less suited.
The entire population will change as, those better suited continue to reproduce, meaning the population becomes better adapted to its environment.
PepperedMothSimulationActivity

25. Evidence…… 1 Fossil record 2 Geographic Distribution of Living Species
3 Homologous Body Structures
4 Similarities in Early Development
5 Biochemical Evidence

26. 1. Fossil Record Trace Fossils - Footprint Cast/Mold Fossils
Preserved Fossils - Amber

27. Determining the Age of a Fossil
1. Relative Dating
tell when organisms lived in reference to other organisms
older organisms show simpler body structure, while more recent organisms are more complex
many fossils show strong similarities to existing organisms

28. Determining the Age of a Fossil
2. Radioactive Dating
Calculate a more accurate age for a fossil based on the amount of radioactive isotopes that remains.

29. 2. Geographic Distribution
Beaver
NORTH AMERICA
Muskrat
Capybara
SOUTH AMERICA
Coypu
Beaver and Muskrat
Coypu and Capybara
Darwin realized that similar
animals in different locations
could be unrelated species.

30. 2. Geographic Distribution
Different variations in populations, due to environmental pressures still share similarities due to a common ancestor
2. Geographic Distribution

31. 3. Homologous Body Structures
Parts of different organisms that are similar in structure but serve different purposes
Suggest evolutionary descent from a common ancestor
Examples include forelimbs of a horse, bat, whale, & human

32. Homologous Body Structures -Comparative Anatomy
Turtle
Alligator
Bird
Mammals
Primitive Fish

33. Homologous structures
Parts of different organisms that are similar in structure but serve different purposes
Suggest evolutionary descent from a common ancestor
Examples include forelimbs of a horse, bat, whale, & human
Bird
Horse
Human

34. Vestigial organs serve little or no function remnants of organs that
were once functioning in an
ancestral form
examples: human appendix, human ear muscles

35. 4. Similarities in Early Development
examples include similar vertebrate embryos in pigs & humans
similarities suggest a common ancestor

36. 5. Biochemical Evidence
DNA
RNA
Proteins

37. Evidence of Evolution includes The fossil record
Geographic distribution of living species
Homologous body structures
Similarities in early development
which is composed of
which indicates
which implies
which implies
Fossil Layer Activity and Horse Structure Activity
Physical remains of organisms
Common ancestral species
Similar genes

38. Once again…..The Theory
Organisms have a tendency toward overproduction (seeds, offspring) because not all organisms will survive.

39. Once again…..The Theory
2. Variations exist in any population and some are inherited.

40. Once again…..The Theory
3. Individuals better suited to their environment live longer and therefore produce more offspring than those less suited.

41. Once again…..The Theory
4. The entire population will change as those better suited continue to reproduce, meaning the population becomes better adapted to its environment.

42. The Theory
Organisms have a tendency toward overproduction (seeds, offspring) because not all organisms will survive.
Variations exist in any population and some are inherited.
Individuals better suited to their environment live longer and therefore produce more offspring than those less suited.
The entire population will change as, those better suited continue to reproduce, meaning the population becomes better adapted to its environment.
PepperedMothSimulationActivity