1. CHAPTER 15
EVOLUTION

2. EVOLUTION IS CHANGE IN SPECIES OVER TIME
Orderly succession of changes.
Change of populations of organisms over generations.
Fossil record shows a modification process at work.

3. EVIDENCE SUPPORTING THE THEORY OF EVOLUTION:
The Fossil record
Comparative Anatomy
Embryology
Biochemistry
Real life Examples

4. 1. The FOSSIL record
Traces of long-dead organisms (10,000 years old at the least 2B fossil).
Found in sedimentary rock.
Examples: cast, mold, or petrified.
Robert Hooke 1668 says they’re not rocks- smarty pants, not just microscope dude.

5. STRATA
successive
layers of
rock
deposited
over
geologic
time.

7. Geologic History of Earth The Fossil Record
LAW OF SUPERPOSITION
Successive layers of rock or soil were deposited by wind or water.
Lowest STRATUM is the oldest.
Top STRATUM is the most recent.
Relative or absolute age can be determined.
Patterns of mass extinctions.
5 so far (we are in the 6th)

8. GEOLOGIC HISTORY OF EARTH
ARCHEAN- prokaryotes arise
PROTEROZOIC- eukaryotes arise
PALEOZOIC- marine invertebrates, fish, amphibians, reptiles, plants arise
MESOZOIC- dinosaurs rule
CENOZOIC- mammals diversify

9. DISCOVERIES FROM THE FOSSIL RECORD
Earth’s history is more than 100,000 times longer than recorded human history (4.5 billion NOT 6K years).
Pattern: species appear-exist-disappear-new arise etc.
Mass extinctions due to drastic environmental change.
5 so far and we are currently in the 6th one
Biogeography (studying the global distribution of fossils and living organisms) shows a logical pattern.
ie. kangaroos only live (Australia) where kangaroo ancestor fossils are found- Australia.

10. PANGEA = ALL LAND

12. ARCHAEOPTERYX
Bird-
Dinosaur
link

13. 2. COMPARATIVE ANATOMY
compare anatomy of species to infer (figure out) evolutionary relationships.
1. Homologous Structures reveal the pattern of divergent evolution.
2. Analogous Structures reveal a pattern called convergent evolution.
3. Vestigial Structures show divergence from an ancestor.

14. HOMOLOGOUS STRUCTURES
Are similar features that originated in a common ancestor that are adapted and modified for different functions.

15. HOMOLOGOUS STRUCTURES reveal common ancestry and a pattern of evolution called DIVERGENT EVOLUTION.

16. ANALAGOUS STRUCTURES
Look-alike structures in unrelated species form as a response to
similar “selection pressures” ex. The fat insulated, streamlined
bodies of penguins (bird), sharks (fish) and dolphins (mammal).

17. HUMMINGBIRD wings- endoskeleton (bones)

18. HUMMINGBIRD MOTH wings-
exoskeleton… not arms

19. Similar environments selected for superficially similar adaptations.
Analogous structures reveal a pattern of evolution called convergent evolution.
Similar environments selected for superficially similar adaptations.
Hedgehog, porcupine, echidna all evolved the quills independently.

20. VESTIGIAL STRUCTURES
are features that serve no useful purpose but show relationships to ancestors in which the structure WAS useful.

21. examples of vestigial structures:
Tailbone in humans no longer useful because we don’t have a tail/muscles attached to it. Shows our primate heritage.
Blind mole rat eyes (non functional) covered by layer of skin.
Human body hair- goose bumps… (hair fluffs up for insulation or to make the organism look bigger).
Penguins and dodo birds have hollow bones (adaptation for flight) even though they don’t fly.

22. 3. E M B R Y O L G
Embryological development
reveals evolutionary history

23. Von Baer- correct simple observation
Embryos of different vertebrate species could not be as easily distinguished as adults of that species.
Earnest Haeckel- WRONG theory “biogenetic law”
- “ontogeny recapitulates phylogeny”
- development retraces evolutionary history (time machine)
- sketches exaggerated/ time machine idea crazy.
Genes that are “common” are expressed (turned on) early in development.
Genes that differ (mutations that accumulated in the different species) are expressed later.
Modern evidence- Hox genes / developmental pathways.

24. From Campbell Biology
Closely related organisms go through similar stages of development.
The theory of recapitulation is an overstatement.
Although vertebrates share many features of embryonic development- it is not as though a mammal first goes through a ‘fish stage’, then an ‘amphibian stage’, and so on.
Ontogeny can provide clues to phylogeny but it is important to remember that all stages of development may become modified over the course of evolution.

25. 4. BIOCHEMISTRY COMPARE DNA OR AMINO ACID SEQUENCES
MORE SIMILAR = MORE RECENT COMMON ANCESTOR
DNA mutations occur at a steady rate. The number of differences are used to create a “MOLECULAR CLOCK” to better estimate divergence from common ancestors.

26. COMPARISON OF DNA SEQUENCES CONFIRM THE EVOLUTIONARY HISTORIES SUGGESTED BY FOSSILS AND ANATOMY.
Ex. chimps and humans share 98-99% DNA

27. 5. EXAMPLES of evolution

28. … post industrial revolution England changed the moth’s environment
… post industrial revolution England changed the moth’s environment. Lichen on tree bark turned black from factory-released soot & smoke.
The Peppered Moth

29. Industrial melanism
The “right stuff” (phenotype) used to be the light coloration.
The “right stuff” became the dark coloration phenotype.
Black moths were hidden from predators.
Black colored moths became more abundant in the population = microevolution.

30. Insecticide resistance ex. Raid Bug spray on cockroaches

31. Few insecticide resistant mutants survive and reproduce (preadaptation)

32. population made mostly of “resistant” mutants… spray insecticide

33. Insecticide ineffectual at killing insects !

34. Antibiotic resistant microbes!TB
Gonorrhea
Staph MRSA
pneumonia

35. PATTERNS OF EVOLUTION Co-evolution Convergent evolution
Divergent evolution
Adaptive Radiation
Parallel Evolution

36. PATTERNS OF EVOLUTION
Co-evolution (arms race) organisms “drive” each other’s evolution
Predator-prey, parasites-hosts, plants-pollinators
Convergent evolution (come together) same environment selects similar phenotypes
(analogous structures) Insect & Bird wings
Divergent evolution (go apart) different environments selects different phenotypes
(homologous structures) your hand and bat wing

37. Adaptive Radiation
divergent evolution of many species from one common ancestor.
Ex. Galapagos finches, mammals
5. Parallel Evolution
The convergent evolution of species adapted tot he same way of life after a divergence occurred.
Ex. Marsupial & Placental mammals… ex. sugar glider & flying squirrel.

38. COEVOLUTION is the change
of two or more species due to their close interactions.
Predator-prey
Ex. cheetah-gazelle
Parasites-host
Ex. viruses-cells
Herbivore-plant
Ex. tortoise-cactus
Plants-pollinators
Ex.flowers-moths

39. CARRION FLOWER SMELLS LIKE ROTTING MEAT TO ATTRACT IT’S INSECT POLLINATORS- FLIES

40. CONVERGENT EVOLUTION
Occurs when the environment selects similar phenotypes (forms) even though the ancestors are quite different.
Bird/fish/mammal all have fat insulated, stream lined bodies with flippers.
Analogous Traits

42. D I V E R G N T
Divergent Evolution occurs when two or more related populations become more and more dissimilar- due to differing habitats…
this RESULTS in NEW SPECIES & Homologous Traits

43. ADAPTIVE RADIATION OF DARWIN’S FINCHES… much divergent evolution from a single ancestral species.

44. Two ideas about
the rate of
speciation…
Either long periods
Of “stasis”
Followed by
Rapid periods of
Evolution Or
Gradual consistent
Change.
Punctuated Equilibrium
Gradualism

45. Parallel Evolution… The Placental vs. Marsupial split occurred
Long ago. Nature selected “for” similar adaptations in both
Lineages to fulfill the same niche on separate continents.

48. “inheritance of acquired characteristics”
EVOLUTIONARY THEORY:
LAMARCK
“inheritance of acquired characteristics”
DARWIN
“natural selection”

49. LAMARCK’S EXPLANATION
Similar species descended from a common ancestor.
ACQUIRED TRAITS were passed to offspring.
Acquired traits- determined by behavior NOT genetics.
Duck’s webbed feet come from “stretching” their toes.
Human’s lost tail because they “don’t use it”.
Girraffe’s long neck ‘cause they “stretched” to reach leaves.
WRONG & EASILY DISPROVED
LAMARCK’S EXPLANATION

50. CHARLES DARWIN
“NATURAL SELECTION”
Organisms best suited to their environment reproduce more than those who aren’t.
Favorable traits increase in populations over time.
Differences exist between members of the same species.
Competition for resources.

51. DARWIN’S INFLUENCES
UNIFORMITARIANISM earth undergoes processes like earthquakes, volcanoes, erosion, sedimentation repeatedly.
Modification of environments is slow, but inevitable.
Earth is old! 4.5 billion years not 6 thousand.
Charles Lyell
Principles of Geology

52. GALAPAGOS ISLANDS are relatively young… formed 5 mya
5 year H.M.S. BEAGLE voyage to
the GALAPAGOS ISLANDS
GALAPAGOS ISLANDS are relatively young… formed 5 mya

53. FINCHES

54. DARWIN’S OBSERVATIONS
Earthquake in Chile- land lifted 3 feet around harbor.
Marine Fossil Shells in the Andes Mountains (14Kfeet).
Galapagos finches (13)
Galapagos tortoises
Angrecum Orchid & pollinator with a long tongue.
Thousands of species observed and documented.

55. WHAT IS FITNESS??? Having the “right stuff” at the “right time”
Favorable traits give the organism who has it an ADAPTIVE ADVANTAGE
HIGH REPRODUCTIVE SUCCESS!!!
Populations adapt to their environment as the proportion of favorable genes increase

56. POPULATION ADAPTED TO HIDE FROM
PREDATORSIN THIS CASE, THE RIGHT STUFF
IS BEING BROWN.

59. RECAP OF EVENTS
1800ish LAMARCK’s Inheritance of Acquired Characteristics
1831 BEAGLE VOYAGE
1858 DARWIN’s On the Origin of Species by Means of Natural Selection
1. Descent with modification
2. Modification by natural selection

60. TYPES OF NATURAL SELECTION

61. TYPES OF NATURAL SELECTION
Stabilizing selection
Directional selection
Disruptive selection
Sexual selection
Artificial selection

62. STABILIZING
SELECTION

63. Stabilizing Selection
eliminates extreme individuals.
A plant that is too short may not be able to compete with other plants for sunlight.
However, extremely tall plants may be more susceptible to wind damage.
Combined, these two selection pressures act to favor plants of medium height.

64. DIRECTIONAL
SELECTION

65. Directional Selection
selects against one extreme.
In the familiar example of giraffe necks, there was a selection pressure against short necks, since individuals with short necks could not reach as many leaves on which to feed.
As a result, the distribution of neck-length shifted to favor individuals with long necks.

66. DISRUPTIVE
SELECTION

67. Disruptive selection eliminates intermediate individuals.
imagine a plant of extremely variable height that is pollinated by three different pollinator insects: one that was attracted to short plants, another that preferred plants of medium height, and a third that visited only the tallest plants.
If the pollinator that preferred plants of medium height disappeared from an area, medium height plants would be selected against, and the population would tend toward both short and tall plants, but not plants of medium height.

68. Sexual Selection

69. The evolutionary process is sped up through ARTIFICIAL SELECTION