1. Standard 5 Unit 12 – Evolution & Biodiversity

2. Objective
B5.1A: Summarize the major concepts of natural selection (differential survival and reproduction of chance inherited variants, depending on environmental conditions).
B5.1c: Summarize the relationships between present-day organisms and those that inhabited the Earth in the past (e.g., use fossil record, embryonic stages, homologous structures, chemical basis).

3. Theory of Evolution
Idea supported by scientific evidence (but no concrete experiments) over a long period of time
Change in a species due to mutation of the DNA code that occurs over a long time.
Evolution is the result of genetic changes that occur in constantly changing environments.
Evolution is all the changes that have transformed life from its earliest forms to what we see today.
Working definition = Evolution is the progressive change in organisms over time.

4. Evolution of Air Breathing:

5. Evolution of Brains:

6. Charles Darwin “Survival of fit” Fit reproduce
Natural Selection:
“Survival of fit”
Fit reproduce
Competition for resources
Best adapted species survive
Introduction to Charles Darwin's Theory of Evolution (00:54)

7. HMS Beagle Voyage 1835 Darwin’s Voyage of Discovery
A reconstruction of the HMS Beagle sailing off Patagonia.

8. The 5 Year Voyage of the Beagle

9. Darwin’s key ideas:
A. REPRODUCTION: Organisms produce more offspring than can survive
B. VARIATION:Variety in traits exist
C. SURVIVAL OF THE FIT: Some traits allow survival & are passed on
D. Over time certain variations make up most of a population & they may be different from their ancestors

10. Darwin’s Ideas Did Not Develop in a Vacuum
Contributor’s to Darwin’s thinking included:
Charles Lyell – uniformatarianism
Georges Cuvier – species extinction
Thomas Malthus – struggle for existence
Jean Baptiste de Lamarck – evolution by acquired characteristics.
Alfred Russel Wallace Independently Drew the Same Conclusions as Darwin

11. Malthus’s contribution:
Populations grow to a maximum level
Environmental limitations
Fit animals out compete the less fit P O U L A T I N
Carrying
Capacity

12. Darwin’s Observations & Inferences
Observation 1: Left unchecked, the number of organisms of each species will increase exponentially, generation to generation.
Observation 2: In nature, populations tend to remain stable in size
Observation 3: Environmental resources are limited.
Observation 4: Individuals of a population vary extensively in their characteristics with no two individuals being exactly alike.
Observation 5: Much of this variation between individuals is heritable.

13. Darwin’s Observations & Inferences
Inference 1: Production of more individuals than can be supported by the environment leads to a struggle for existence among individuals, with only a fraction of offspring surviving in each generation.
Inference 2: Survival in the struggle for existence is not random, but depends in part on the heritable characteristics of individuals. Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals.
Inference 3: The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection).
Taken together, these three inferences are a statement of Darwin’s Theory of Evolution.

15. Evolution Evidence: 1. Adaptations 2. Fossils 3. Comparative anatomy
4. Comparative embryology
5. Comparative Biochemistry
6. Plate Techtonics

16. 1. Adaptations: features suited to a particular environment that allow organisms to survive
Inuit people, who live in the extreme cold of the Arctic, have short, stout bodies that conserve heat.

17. Adaptations
Masai people, who live in the arid lands of eastern Africa, have tall, lean bodies that disperse heat well.

18. Plant Adaptations: Venus Fly Trap Captures Animals Acquires Minerals
For Photo-
synthesis
Help!!!

19. Leaf Adaptations:
Succulents
Thick
Store Water
Prevent Drying out

20. Leaf Adapatations: Pine Needles Shed snow Less water loss
Reduced surface area
Tolerate wind

21. Flower Adaptations: Fly pollination: Hair along petals Putrid smell
Bee pollination:
Smooth petal
Sweet smell

22. 2. Fossil Evidence: Once living remains of organisms Limited to:
The Evidence for the Theory of Evolution (02:04)
Once living remains of organisms
Limited to:
Type of material preserved (bone, shell, impressions, amber)
Incomplete record
Easily disrupted

23. Plant Fossil Evidence:

24. 3. Comparative Anatomy: Structural similarities link related species

25. Comparative Anatomy Structures:
Analogous:
Different ancestors
“analogy”=like
Different underlying structures
Same Function
Similar Environments
Homologous:
Same ancestor
“homo”=same
Same underlying structures
Different Functions
Different Environments

26. Analogous Structures
Different underlying structures (different ancestors)
Same function, similar environments

27. Homologous Structures:
Same underlying structures, different functions, different environments & common ancestor

28. 4. Comparative embryology:
Similar embryo development in closely related species

29. 5.Comparative Biochemistry
Similar DNA sequences=
Similar Gene segments of the DNA
Code for similar traits
In closely related species

30. Kinship
There is a degree of kinship between organisms or species that can be estimated from the similarity of their DNA and protein sequences.
Chimpanzees are so closely related to humans that they should properly be considered as members of the human family, according to new genetic research.
Scientists from the Wayne State University, School of Medicine, Detroit, US, examined key genes in humans and several ape species and found our "life code" to be 99.4% the same as chimps.
They propose moving common chimps and another very closely related ape, bonobos, into the genus, Homo, the taxonomic grouping researchers use to classify people in the animal kingdom.
Humans, or Homo sapiens to give the species its scientific name, are the only living organism in the genus at the moment - although some extinct creatures such as Neanderthals (Homo Neanderthalis) also occupy the same grouping.
Dr Wildman said: "You could say that humans and chimps are as similar to one another as say horses and donkeys.

31. Evidence of Evolution –Conservation and Diversification at the Molecular Level
Why should different organism possess related genes?
Why does the degree of relationship of genes match their degree of relationship established by other methods?

32. Evidence for Evolution –Evolution Observed
Evolution of pesticide resistance in response to selection.
Evidence for Evolution –Evolution Observed

33. Evidence for Evolution –Evolution Observed
Evolution of drug-resistance in HIV

34. 6. Plate Techtonics Geological theory:
Continental masses were one land mass that explains
Closely related species have common ancestors on now separated continents

35. What Darwin Never Knew

36. Movie
Trace the relationship between environmental changes in the gene pool, such as genetic drift and isolation of subpopulations.
Biomes: Islands and Evolution (56:00)

37. Early Theories of Evolution:
Darwin:
Current theory
Natural Selection
“Survival of fit”
Reproduction of the best adapted species
Lamark:
“Use & Disuse”
Abandoned
No knowledge of genetic traits or mutations in sex cells

38. Lamark’s Theory Use of structure results in evolution
“Use and Disuse”
Use of structure results in evolution
Does not take into account DNA or sex cell mutations

39. Mechanisms of Natural Selection

40. I. What is evolution?
A change in the genetic makeup of a population with time.
It is a two-step process
Development of genetic variability in the population.
Natural selection of those variations which are favorable for survival.

41. Example
Let’s say a population of black spotted cattle--BB-- eventually turn into a population of white spotted cattle--bb-- over a period of years.

42. II. Genetic variability
Assuming that a population starts out with the same genetic makeup, all new genetic material in that population will arise by mutation.
A mutation is a random inheritable event.
Let’s take our black spotted cattle as an example; for some reason the chromosomes that code for black spots are mutated.

43. Variability
This mutation Changes the BB to Bb. Now with the b gene in the herd, White spotted cattle can arise.

44. Variation
Variation in the chromosomes occurs when an egg and a sperm unite. Both carry unique traits from the parents into one individual, forming an individual which varies from the parents.
This variation is normally a random event.
In our example, let’s say two mutated animals mate with one another. Let’s look at their offspring.

46. A Scenario to demonstrate natural selection
It has been 50 years since the first mating of our mutated cattle. Over the years the once all Black spotted (BB) herd is now about 75% black spotted and about 25% white spotted (bb).
A new disease has mutated during this time period. A disease known as Bovine Black Spotitis. The disease is not fatal, but any black spotted (BB or Bb) bull or cow is sterile.

47. Question?
The disease spreads quickly through the herd and within six months time all black spotted cattle are sterile.
What will eventually happen to the herd?

48. Answer
Only the white cattle will be able to reproduce, eventually producing a completely herd of white spotted cattle. (bb)

49. Natural Selection
As long as the environment does not again change then these individuals will become the “normal” population.
The sequence of events that leads to a certain characteristic being “selected” in the environment is called natural selection.
Populations change in response to their environment.
Acts on phenotype of an organism.
(Not genotype)
Determines the differential survival of groups of organisms

50. Evolution’s Core Principles
Natural selection

51. Evolution’s Core Principles
Common descent with modification
Macroevolution: Long time scale events that create and eliminate species

52. Variations: Differences in traits Come about by mutations in genes
Random
Occur in sex cells
Passed on to future generations

53. Bird Beak Adaptations:

54. Genetic Drift Changes in the gene pool due to:
Random mating
Over a long time period
No immigration of males
No emigration of females
Sufficient resources that match the adaptations

55. Same Species Must: Donkey + Horse= Mule (infertile)
Show similar characteristics
Successfully
interbreed
Producing fertile offspring
Donkey + Horse=
Mule (infertile)

56. Speciation Evolution New Species Over time By Isolation
Natural Barriers

57. Speciation
Formation of a new species

58. Geographic Isolation
Separation of organisms by geographic features. A physical barrier divides a population:
Mountains
Lakes, oceans, rivers
Desserts
These two groups are not able to mate
=> may lead to new species

59. Reproductive Isolation When two different species can not mate and have successful offspring
Geographic barriers
Anatomy or physiology
Social behaviors
Prevention of mating between formerly interbreeding groups. or
The inability of these groups to produce fertile offspring

60. Reproductive Isolation: Two organisms cannot mate
Separated by geographic boundaries
Anatomical differences
Physiological differences
Social behaviors

61. Gradualism
“gradual”
Small changes
Over a long time

62. Gradualism
Model of evolution involving slow, gradual changes to a species over time.

63. Punctuated Equilibrium
“punctuation!”
Large changes
Happen rapidly
Periods of no change

64. Punctuated Equilibrium
Evolutionary model
Rapid changes to a species in a short time, followed by periods of little change.

65. Gradualism vs. Punctuated Equilibrium# S P E C I
Time

66. Gradualism vs. Punctuated Equilibrium

67. Adaptive Radiation: “radiation”= branching from one source
“adaptive”= survival of fit
Evolution of many branches of organisms from a single source

68. Adaptive Radiation

69. Divergence Original Species: Mammal Homologous structures Same origin
Human arm
“diverge”= branch off
Homologous structures
Same origin
Same underlying structure
Difference functions
Bat wing
Cat limb
Whale flipper
Original Species:
Mammal

70. Convergence “converge”=come together” Analogous features
From different origins
Similar environments=
Similar functions
Different structures
* Homework – 43-1
Bird wing
Organisms that fly
Butterfly wing
Bat wing

71. Convergent Evolution
Placental mammals
Marsupial mammals

72. Convergent Evolution
Although marsupial mammals once populated all land masses, they remain diversified only on the isolated Australian continent, where they have evolved to fill the same ecological niches that placental mammals occupy elsewhere. The Tasmanian wolf, for example, closely resembles the doglike carnivores of other continents. More specialized parallel adaptations include those of the marsupial and placental anteaters, the marsupial sugar glider and placental flying squirrels, and the burrowing marsupial wombat and placental ground hog. In this illustration, placental mammals are in the top row, and their marsupial equivalents are in the bottom row.

73. Genetic Variation
* Homework – Give examples of ways in which genetic variation and environmental factors are causes of evolution and the diversity of organisms.