1. CHAPTER 14
ORIGINS OF LIFE

2. Spontaneous Generation
for much of history, people believed that animals could come from non-living sources.
this is called abiogenesis
also known as spontaneous generation

3. Francisco Redi (pg 261)

4. Redi’s critics said: You have excluded AIR
We ALL know that everything needs air
Of course no flies grew!
You haven’t proven anything.

5. Redi part 2 – answer to critics
fine mesh allows in air, but not flies
flies laid eggs on top of mesh
no maggots in meat

6. BIOGENESIS
Defintion- all living things must come from other living things
This was now obvious for larger animals-- but what about bacteria???

7. LAZZARO SPALLANZANI’S EXPERIMENT (PG 262)
tight seal
loose seal
30 mins
LAZZARO SPALLANZANI’S EXPERIMENT (PG 262)
60 mins
he did TIMED BOILINGS
then left them partially sealed
some partially sealed, some hermetically sealed as in his previous experiment
hypothesized that more boiling should lead to less life
90 mins
120 mins

8. Spallanzani’s results
Boiling time had no effect on the broth The broth that was SEALED stayed the freshest for the longest time regardless of boiling time.

9. Louis Pasteur’s Experiment 1859 (pg 263)
used swan- necked flask
flask allowed in air, but trapped dust (and microbes)
boiled infusion
showed that NO growth occurred, even after many days

10. pasteur Pasteur showed that the active principle was NOT damaged
at any later time, he could tip the flask
this allowed nutrient broth to contact the dust
this carried microbes into the broth
result: growth!
area where dust had been trapped

11. DATING of the EARTH
EARTH’s estimated age--- more than 4 billion years How have scientist predicted this????

12. RADIOACTIVE DATING
Using the HALF-LIFES of radioactive material to determine age
HALF-LIFE- the time it takes ½ of the mass of a radioactive isotope to breakdown into it’s non radioactive counterpart
Example
Carbon-14 turning to carbon 12 (half life is 5730 years)

13. DATING OF FOSSILS
LAW OF SUPERPOSITION- successive layers of rock or soil are deposited one on top of the other. The lowest layer (STRATUM) is the oldest while the top layer (STRATUM) is the most recent.
RELATIVE AGE- determined by which layer of rock the fossil is found in
ABSOLUTE AGE- more precise age by using radioactive dating (Carbon Dating)

14. SCIENTIFIC PROOF OF LIVING ORGANISMS
FOSSIL- trace of a long dead organism (examples----bones, teeth, shell, imprints “MOLDS”, footprints,

15. EVIDENCE OF LIFE
EXTINCTION- the disappearance of a species MASS EXTINCTION- the disappearance of many species- probably due to a dramatic change in earth’s atmosphere BIOGEOGRAPHY-- comparing present day organisms with fossils from the area (example Armadillo)

16. PRINCIPLE OF UNIFORMITARIANISM
Principle that the changes that occur on Earth present day are similar to the changes that have occurred on early Earth

17. FIRST PROKARYOTES
Probably ARCHAEBACTERIA- that could survive the tough atmospheric and temperature conditions
CHEMOSYNTHETIC- used chemicals to make energy

18. FIRST PROKARYOTES
Chemosynthetic bacteria slowly gave rise to photosynthetic bacteria
CYANOBACTERIA- first known photosynthetic organism
3.5 billion year old microfossils have been discovered

19. FIRST EUKARYOTES
CYANOBACTERIA combining with other prokaryotes- probably gave rise to eukaryotes
ENDOSYMBIOSIS- mutually beneficial joining of two organisms
(example- E. coli and the human intestine)

20. THEORIES OF EVOLUTION
LAMARCK- proposed that similar species descended from a common ancestor
Example– giraffes came from horses
ACQUIRED TRAIT- trait not determined by genes but by the organisms behavior that result in a change in the species
Example– giraffes necks became longer as they started eating leaves off of trees

21. Charles Darwin Traveled around the world collecting organisms
Noticed many organisms in each ecosystem were different in form, function and behavior
He believe these differences were hereditary
Developed the term “NATURAL SELECTION”
Species that were best suited to their environment would reproduce more successfully thanother organisms

22. Darwin’s first theory
DECENT WITH MODIFICATION– newer forms of a species are modified descendants of older species
“One species could actually become many different species”

23. Darwin’s second theory
MODIFICATION BY NATURAL SELECTION-
Environment determined which individuals passed down traits

24. NATURAL SELECTION
Defined as the unequal survival and reproduction that results from the presence or absence of particular traits due to competition
Natural selection leads to EVOLUTION

25. 5 Characteristics of Natural Selection
1. Organisms produce more offspring than can survive in the wild (give an example) 2. The environment is hostile and contains limited resources. (food, water, space, and predator/prey) Competition can be between individuals or between species. 3. Organisms differ in the traits that they have. 4. Some traits provide an advantage 5. Each generation contains more organisms with the advantageous traits

26. DEFINITIONS
POPULATIONS- one species in one place at one time ( can interbreed)
FITNESS- the ability of a species to survive and pass down their genes (how many grandchildren do they have?)
ADAPT- to change genetically in a population to better survive in an environment
ADAPTIVE ADVANTAGE- having a trait that is favorable in an environment
ADAPTIVE RADIATION- one species splitting into many different species

27. EVIDENCE OF EVOLUTION (5)
HOMOLOGOUS STRUCTURES- similar features that originated in a shared ancestor-- example- bones of the hand, number of cervical vertebrae
ANALOGOUS STRUCTURES- similar structures on totally different species with the same function-- Examples- wings on birds and insects

28. EVIDENCE OF EVOLUTION (5)
3. VESTIGIAL STRUCTURES- structures that no longer have a functions (example- appendix)
4. SIMILARITIES IN DNA AND RNA

29. EVIDENCE OF EVOLUTION (5
5. SIMILARITIES IN EMBRYOS
“Embryological development repeats evolutionary history”

30. COEVOLUTION
Two species evolving in response to long-term interactions with one another
DIVERGENT EVOLUTION- species become more and more different from one another due to the environment-- can lead to new species
CONVERGENT EVOLUTION- two completely different species becoming more and more similar due to the environment

31. ARTIFICIAL SELECTION
Defined as Selective breeding by humans for specific characteristics
Examples- breed dogs for hunting, or to be pets (size and behavior)
breed plants to produce more food or be resistant to drought or disease

32. POPULATION GENETICS
Study of evolution from a genetic point of view. Study of the change in the GENE POOL for a population Example- in a garden what percent of the roses are Red (RR), pink (Rr) or white (rr)

33. ALLELES
Possible traits of a gene ALLELE FREQUENCY- how common a specific allele is in the gene pool PHENOTYPE FREQUENCY- how common a specific phenotype is in a population

34. Allele frequency

35. ALLELE FREQUENCIES vs PHENOTYPE FREQUENCIES
Although phenotype frequencies tend to change generation to generation. Allele frequencies tend to stay the same. HARDY WEINBERG EQUILIBRUIM--- p2 + 2pq + q2 = 1

36. HARDY WEINBERG EQUILIBRUIM-
1.    mutation is not occurring
2.   there is no migration in or out of the population
3.   the population is infinitely large
4.   natural selection is not occurring
5.   all members of the population breed
6.   everyone produces the same number of offspring
7.   all mating is totally random

37. Mutations Can add a new allele into the mix
IMMIGRATION or EMIGRATION- can add or subtract a bunch of individuals with one specific allele

38. Small Populations
GENETIC DRIFT- the alelle frequency chances simply due to chance link to Simulation notice how the value for P will either climb to 1 or go all the way down to 0

39. No natural selection
All individuals have to have an equal chance of survival reproduction and have the same fitness.

40. Random Mating (No Sexual Selection)
NO ASSORTATIVE MATING
All individuals must reproduce at the same rate.

41. Bell Curve of Phenotypes

42. DIRECTIONAL SELECTION
Individuals that have one extreme of a trait show a higher fitness
Center of the graph moves in one direction

43. STABILIZING SELECTION
Individuals with the most average form of a trait have the highest fitness
Graph– gets taller and narrower in the middle

44. DISRUPTIVE SELECTION
Individuals at either extreme have the highest fitness
****This can lead to one species become two different species.
Single parabola slowly turns into 2 parabolas

45. Microevolution vs macroevolution
Micro-- small changes in a species
Macro- large transformations in a species

46. microevolution
is the changes in allele frequencies that occur over time within a population. This change is due to four different processes: mutation, selection (natural and artificial), gene flow, and genetic drift.

47. Genetic drift ----or allelic drift
is the change in the frequency of a gene variant (allele) in a population due to random sampling.
occurs in smaller populations much faster

48. FOUNDER’S EFFECT
is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population.

49. BOTTLENECK-
a sharp reduction in size of a population due to environmental events (such as earthquakes, floods, fires, or droughts) or human activities.

50. Bottleneck examples
One real life example of a species being affected by the bottleneck effect is the northern elephant seal. Humans intensely hunted these animals in the late nineteenth century, and their population was reduced to just twenty at one point. Though the species has recovered and there are over 30,000 northern elephant seals today, there is not a lot of genetic diversity among members of this species.

51. Bottleneck examples --Any ENDANGERED SPECIES ---Giant Panda
--- Prairie Chicken
--- Amish
---Inhabitants of small islands (Iceland)

52. Microevolution by ISOLATION
REPRODUCTIVE ISOLATION-- individuals are split from the rest of the population due to some type of barrier

53. Types of isolation
GEOGRAPHIC ISOLATION- populations that have been separated by physical barriers
--Mountain ranges
--Rivers- (Grand Canyon)
--Ocean- (organisms separated on different islands)
--Human Interference ---dams, highways, fences

54. Types of isolation
BEHAVIORAL ISOLATION– (ethological)--- various courtship rituals or other behaviors interfere with interbreeding
Ex- Eastern and Western Meadowlark have different songs.
Crickets are very species specific in their songs

55. TEMPORAL ISOLATION-- species that reproduce at different times
Types of isolation
TEMPORAL ISOLATION-- species that reproduce at different times
Flocks of Canadian Geese migrating at different times
Flowers that bloom at different times

56. TEMPORAL ISOLATION-

57. macroevolution Large changes in a species Rate of EVOLUTION
1. GRADUALISM
2. PUNCTUATED EQUILIBRIUM

58. GRADUALISM
Defined as a profound change being the sum of many slow and steady changes
Ex- ostrich wings becoming smaller and smaller as the birds evolved.

59. Punctuated equilibrium
“rapid evolution” due to large changes in the environment
Examples-
volcanoes forming new islands
Small group becomes isolated
New species enters the ecosystem

60. ADAPTIVE RADIATION
Single species or small group of species evolves into several different forms
Ex- Mammals where quite small species during the days of the dinosaur. When the dinosaurs went extinct many species began large changes.
(elephants, whales, rhino)
Darwin’s finches- one species of finch turns into many different species.

61. Is a hippopotamus more closely related to a pig or to a whale
Is a hippopotamus more closely related to a pig or to a whale? List 3 reasons to defend your answer.

62. HIPPO WHALE
Based on physical comparisons (particularly dental structure and number of toes) it was originally thought that hippos were most closely related to pigs but DNA analysis indicates that hippos are more closely related to whales!

63. PHYLOGENY
the study of evolutionary history and relationships of organisms
Use more DNA now than morphology-
Can classify extinct species-

64. Which pair is more closely related
Which pair is more closely related? A lizard/crocodile or bird/crocodile?

65. Cladograms are used to…
Organize organisms based on evolutionary relationships (phylogeny).
In other words… who is related to who and where did we come from…

66. Important Definitions
Node: a branch point in a tree (a presumed ancestral OTU)
Branch: defines the relationship between the taxa in terms of descent and ancestry (trait)
Topology: the branching patterns of the tree
Branch length (scaled trees only): represents the number of changes that have occurred in the branch
Root: the common ancestor of all taxa
Clade: a group of two or more taxa or DNA sequences that includes both their common ancestor and all their descendants

67. Systematics -cat example
-branch tips = extant spp; root = common ancestor; branches = history of descent; node = point where 1 spp split into 2+ descendents
-lynx & bobcat closest relatives, share a more recent common ancestor with each other than with any other spp on the tree; therefore called ‘sister taxa’
-‘taxon’ any named group of organisms, genus, spp, family etc.
-leopard derived with descent with modification from recent ancestors with similar coats and distant ancestors with flecks
-this is a hypothesis!
-we do not know true history, we identify most plausible scenario
-different data sets can produce different trees
-branch lengths arbitrary, arranged to improve readability
-root establishes order of divergence events

68. Venn Diagram Placenta: Human Mammary glands: Kangaroo & Human
Two pairs of limbs: Bullfrog, kangaroo & Human
Vertebrae: Shark, bullfrog, kangaroo & humans