2. Chapter 16.1: Darwin’s Theory of Evolution:
Objectives:
State Charles Darwin’s contribution to science.
Describe the three patterns of biodiversity noted by Darwin.

3. Darwin’s Epic Journey Charles Darwin – Naturalist
Born in England in 1809
Developed the theory of evolution.

4. Darwin’s Epic Journey Dates: February 12th, 1831 Ship: H.M.S. Beagle
Destination: Voyage around the world
Findings: Collected thousands of plant & animal specimens to propose a hypothesis about how life changes over time.

5. Differences Among Organisms
Species: A group of organisms that can mate with one another to produce fertile offspring.
Adaptation: Characteristic that helps an organism survive and reproduce in its environment.

7. Observations Aboard the Beagle
Darwin noticed 3 patterns of biological diversity:
Species vary globally
Species vary locally
Species vary over time
Darwin not only observed how species adapted to different biomes but also how species had adapted to the same biomes in different parts of the world.

8. Species Vary Globally Similar species in different continents?
South America: Rheas
Africa: Ostrich
Australia: Emu
Conclusion: Similar environments produce species with similar adaptations.

9. Species Vary Locally: Galapagos Islands
Related species had different adaptations in different parts of the same continent.
Example:
Hood Island Tortoise & Isabela Island Tortoise
Finches
Hood Island Tortoise
Isabela Island Tortoise

10. Species Vary Locally: Galapagos Islands
Variation among finches on different islands

11. Species Vary Over Time Darwin also collected fossils.
Fossils: Traces of organisms or “footprints”
Fossil Record: Timeline of life, organizing fossils by their estimated ages and physical similarities.

12. Species Vary Over Time
Darwin’s observations of fossils: Extinct animals were similar to living species
Example:
Extinct Glyptodont vs. Armadillo
Why did the Glyptodont disappear?

13. Do Species Change over Time?
As populations and their environment change over time, new species form.
Evolution: The process in which populations gradually change over time.

14. Chapter 16.2 Essential Questions
What did Hutton and Lyell conclude about Earth’s history?
How did Lamarck propose that species evolve?
What was Malthus’s view of population growth?
How is inherited variation used in artificial selection?

15. Ideas That Shaped Darwin’s Thinking
Geologists Lyell + Hutton discovered that EARTH:
Was much older than previously thought
Changed and is still changing in the same pattern
Principles of Geology, 1809
These ideas helped shaped Darwin’s theories about how organisms adapt to changes on Earth
Hutton: Connections between geological processes and geological features.
Lyell: Uniformitarianism (geological changes now are the same as in the past)
Darwin: If Earth can change over time, could life change too?

16. Lamarck’s Evolutionary Hypotheses
Jean Baptiste Lamarck: 1st naturalist to study adaptations
Suggested 2 theories:
Acquired characteristics
Inheritance of acquired characteristics
First naturalist to study evolution and diversity due to adaptation.

17. Lamarck’s Evolutionary Hypotheses
Theory of acquired characteristics (1809):
Organisms acquire traits during their lifetime to adapt to their environment
Driven by innate tendency toward perfection
Pertained to both use and disuse
Theory of inheritance of acquired characteristics:
Traits acquired during an organism’s lifetime can be passed on to their offspring.
Example: Giraffe’s neck
A water bird could have acquired longer legs because it began to wade in water looking for food. A bird’s wings would get smaller if it stops using its wings.

19. Lamarck Was Wrong!!!
Phenotypic changes do not result in genotypic changes.
However, he was the first to link organism’s environment to its body changes.
Darwin built his theory using Lamark’s ideas.
Lamarck’s ideas were incorrect, because phenotypic changes acquired during an organism’s lifetime do not result in genetic changes that can be passed to subsequent generations.

20. Population Growth Thomas Malthus (1798)
The rate of people being born is higher than the rate of people dying
Theory: If this rate continues, there won’t be enough food and living space.
Darwin related this idea to other organisms, and started wondering why overcrowding does not exist in nature.

21. Artificial Selection
Darwin studied artificial selection by plant and animal breeders.
Artificial selection: Selective breeding
i.e. Can produce variation among species (pigeons)
Darwin realized variation in nature was key for evolution to occur.
At the time scientists did not have any understanding of heredity, but he did discover that variation occurs in all species, which provided the raw material for evolution

22. Darwin’s Thinking – Ideas About Population
Only a limited number of individuals survive to reproduce in a population.
Survivors must have favorable traits.
Only the strongest species will go on to have offspring with these favorable traits.

23. Chapter 16.3 Essential Questions
Under what conditions does natural selection occur?
What does Darwin’s mechanism for evolution suggest about living and extinct species?

24. 1859, Darwin’s theory of evolution was published
Natural Selection
1859, Darwin’s theory of evolution was published
On the Origin of Species by Means of Natural Selection

25. Theory of Natural Selection:
The Struggle for Existence
Variation and Adaptation
Survival of the Fittest

26. 1. The Struggle for Existence
Natural Selection
1. The Struggle for Existence
Population rate forces species to compete for resources
If the rate of birth exceeds the rate of death then members of a population must compete to obtain food and living space.

27. 2. Variation and Adaptation
Natural Selection
2. Variation and Adaptation
Variations are due to adaptations to the environment
Adaptation:
Characteristics increasing
ones chance of survival
Fitness: How well an individual can survive in its environment. Some adaptations give an individual a better advantage over others. Other individuals with low fitness die before they are old enough to have offspring.

28. 3. Survival of the Fittest
Natural Selection
3. Survival of the Fittest
Adaptations effect an individual’s fitness
High fitness
Individuals have a better advantage
Low fitness
Individuals die before having offspring

29. Three types of Adaptations:
Natural Selection
Three types of Adaptations:
Structural
Physiological
Behavioral

30. 1. Structural Adaptations
Warning Coloration
Camouflage
Mimicry
Scarlet king snake (left) is harmless. Poisonous eastern coral snake (right) is harmful.

31. Structural Adaptations
Duck---webbed feet
Fish---gills
Giraffe---long neck
Beaver---large teeth
Whale---blubber
Snake---flexible jaw
Platypus---bill

32. 2. Physiological Adaptations
Chemicals
Toxins
Plants: Methods of pollination or methods of photosynthesis.
Body Temperature

33. 3. Behavioral Adaptations
Scaring Predators
Hibernating
Migrating in “V”
Staying in Groups
Mating Calls

34. Darwin’s Theory of Natural Selection
Natural Selection: Individuals better adapted to their environment survive and reproduce more successfully than less well adapted individuals

35. Natural Selection – Insect Resistance

37. Darwin’s Theory of Natural Selection
Genetics and Evolution
Darwin’s theory (1858) lacked explanation of inheritance of traits and variation
Mendelian genetics (1900s)
Variation is due to differences in genes
Darwin lacked evidence for parts of his theory, such as how traits were inherited and how there was variation in species.
Mendel was born in 1822, but his studies weren’t recognized until the 20th century.

38. Darwin Presents His Case
Over time adaptation could cause successful species to evolve into new species
Living species are descended from common ancestors (Descent with modification)
1st evolutionary tree
Principle of common descent
All species are related to a common ancestor (tree of life)

39. Exploring Various Lines of Evidence for the Theory of Evolution
Evidence of Evolution
Exploring Various Lines of Evidence for the Theory of Evolution

40. Lines of Evidence
Biogeography
Comparative Anatomy
Embryology
Fossil Record
DNA Sequences

41. Biogeography
Biogeography is the study of the global pattern of distribution of species and their ancestors.
Biogeography is the study of the global pattern of distribution of species, including the history and causes of this distribution.

42. Patterns in Distribution (2 Types)
Closely Related But Different
Finches developed different variations depending on the environment of their island but all had a common ancestor from the mainland.
Distantly Related but Similar
Similar species (rheas, ostrich, emu) in different grasslands (Europe, Australia, Africa) do not share a common ancestor, but developed similar adaptations.
Different species of finches developed different variations depending on the environment of their island but all had a common ancestor from the mainland.

43. Evidence for Evolution
Radioactive dating is a technique used to date materials such as rocks, by comparing its abundance of a naturally occurring radioactive isotope to its known decay rates.
Determined Earth is about 4.5 billion years old

44. Evidence for Evolution:
Darwin and His Theory
Evidence for Evolution:
The Fossil Record
10/1/2017
G. Podgorski, Biol. 1010

45. Evidence for Evolution
Fossil Record
Provides evidence about the order in which species have existed

46. Whale Evolution

49. Comparing Anatomy & Embryology
Homologous Structures: Similarities in structures b/w species suggest they descended from a common ancestor
Includes bone structures and embryological development

50. Comparative Anatomy Homologous Structures
Note the color-coded bones for the limbs of these 4 mammals – though different, they share many similar bones.

51. Comparative Anatomy
Same arrangement of bones in cats, dolphins, bats, and humans suggest they share a common ancestor.
The structure and order of bones of a human arm are similar to those of the front limbs of a cat, a dolphin, and a bat.

52. Comparing Anatomy & Embryology
Analogous Structures: Body parts that share common function, but not structure. Do not share a common ancestor.
Example: Wing of a bird and an insect
Vestigial structures: Structures inherited from ancestors that are no longer necessary and have lost their function.
Ex: Hip bone of whale

54. Genetics and Molecular Biology
Genetics gives evidence of common descent among organisms.
We also know that variation is due to shuffling and crossing over in meiosis.

55. DNA Sequences Scientists are able to isolate pieces of DNA.
Species that are more closely related tend to have more similarities in their DNA.

56. DNA Sequences
Leptin = Protein hormone important for regulating body weight and metabolism
Mice without properly functioning leptin gene are morbidly obese (right) compared to normal mice (left).

57. Testing Natural Selection
Darwin’s finches hypothesis:
Beaks of finch species evolved to adapt to the type of food available on the island.
Recently tested by Peter and Rosemary Grant to be true.

58. Testing Natural Selection
The Grants found that if the environment changes quickly and unexpectedly, that finch populations could evolve within decades, confirming that competition and environmental change drive natural selection.
They also showed that variation increases a populations chances of survival.

59. Biogeography
Marsupials are a group of mammals that give birth to live young that develop in an outer pouch of the mother.
Marsupial distribution across the globe:
Distribution today split on two sides of globe – how?
Review a few facts of the distribution and marsupials, as well as the history of the Earth, then formulate hypothesis behind distribution
Bandicoot
Koala
Opossum
Sugar Glider
Kangaroo

60. Biogeography
How do you think some marsupials ended up halfway across the world from the others?

61. Biogeography
Continental Drift over millions of years – watch the movement of land masses

62. Continental Drift + Distribution of Marsupials
Biogeography
Continental Drift + Distribution of Marsupials