1.  Stage 1: Abiotic Synthesis of Organic
Monomers
 Amino Acids
 Chains of nucleotides
 Chains of DNA bases
 Chains of RNA bases
 Building blocks of protein
 Sugars
 Lipids
 ATP

2.  Stage 2: Abiotic Synthesis of Polymers
 Monomers, such as amino acids, spontaneously
fused together to form proteins.

3.  Stage 3: Origin of Self-Replicating Molecules
inheritance
Ribozyme: catalytic RNA used to fuel RNA replication

4.  Stage 4: Formation of
Pre-cells
 Molecular packages with
some properties of life.
 The gap between pre-cells
and true cells is
enormous!
 Natural Selection

5. The origin of
eukaryotic cells
Endosymbiotic Theory
 Membrane bound nuclear
material
 Organelles
 More complex than prokaryotic
cells
 Ancestors to fungi, plants and
animals

6. Concept Map
Section 17-2
Evolution of Life
Early Earth was hot; atmosphere contained poisonous gases.
Earth cooled and oceans condensed.
Simple organic molecules may have formed in the oceans..
Small sequences of RNA may have formed and replicated.
First prokaryotes may have formed when RNA or DNA was enclosed in microspheres.
Later prokaryotes were photosynthetic and produced oxygen.
An oxygenated atmosphere capped by the ozone layer protected Earth.
First eukaryotes may have been communities of prokaryotes.
Multicellular eukaryotes evolved.
Sexual reproduction increased genetic variability, hastening evolution.

8. Evolution = “Descent with Modification”
1. ------------due to being spread over
different habitats and therefore adapting
and modifying themselves to fit the
habitat.
2. Natural Selection
• A population of organisms can
change over generations if certain
inheritable traits leave more
offspring than others and those
others get the chance to reproduce
and continue the lineage.
• Evolutionary Adaptation

9. Greek Philosophers
• Plato’s Idealism
• Aristotle’s scala naturae (scale of
nature)
 special creation of each species
 organisms were created in their current
form
 the earth was only a few thousand years
old

10. THOMAS MALTHUS
 economist & clergyman
 published
An Essay on the Principle of
Population
 Populations had an inherent tendency to increase
geometrically, while the resources needed to support this growth
increase slowly or not at all.
 Because of the continued growth of a species would outstrip
needed resources, growth would be limited.

11. JEAN-BAPTISTE de LAMARCK
 French biologist
 proposed that modern species
descended from other species
 Lamarckism based on two theories:
1. Inheritance of Acquired Characteristics
- traits acquired by an individual during its life are passed to its
offspring
2. Use and Disuse
- organs of the body that were used extensively to cope with the
environment became larger and stronger, while organs that
were not used deteriorated

12. THE ROAD TO EVOLUTIONARY THEORY
Example: Evolution Before Darwin
The Evolution of the Giraffe
Giraffes obtained their long necks from
previous giraffes who stretched to eat the
leaves of high tree branches.
Stretching increased the length of their
necks, and this acquired characteristic
was passed to the next generation.

13. Lamarckism
 first to present a unified theory that attempted to explain the
changes in organisms from one generation to the next
 Although, mechanisms proposed for change was wrong, since
acquired characteristics are not heritable!!!
 origin of species from preexisting species
 ability of organisms to adapt

14. GEORGES CUVIER
 French anatomist and
naturalist and writer
 palaeontologist
 strongly opposed the
concept of evolution
 history of living organisms recorded in layers of rock
containing a succession of fossil species in chronological
order
 fossils were organisms that had died in a series of
catastrophes, after which extinct plants and animals were
replaced by the immigration of distant species to the
devastated region  Catastrophism

15. CHARLES DARWIN
 voyage on the H.M.S.
Beagle (1836)
 published (1859)
The Origin of Species
 first person who proposed
a mechanistic approach to
evolutionary thought
 the father of synthetic
evolution

17.  Galapagos tortoise
Darwin’s finches
Most organisms on the islands
were endemic.

19.  The birds were very similar (common ancestry).
 They all adapted to different Niches.
 Niche = Your job in nature.
 What you eat
 Where you live (on ground, in a tree)
 Reproductive Isolation resulted in speciation.

21. Fossils chronologically
ordered in rock layers

22. Geographic distribution of species: Australian marsupials

23. HOMOLOGY

24. Notice that a
Chimp is more
genetically
related to a
human than to
an Old World
Monkey!

25.  species not specially created in their
present forms, but had evolved from
ancestral species
 proposed a mechanism for evolution:
Natural Selection
A population of organisms can
change over time as a result of
individuals with certain heritable
characteristics leaving more offspring
than other individuals.

27. Darwinism in Historical Context

28. GREGOR MENDEL
 Austrian biologist
 discovered the basic principles of
heredity
 father of Classical Genetics
 Individual characteristics determined
by inherited factors transmitted from
parent to offspring.

29. HUGO CARL ERICH VON
DE VRIES CORRENS TSCHERMAK
 rediscovered Mendel’s laws of heredity
 the start of rediscovering evolution in terms of Mendel’s
ideas

30. JAMES WATSON
FRANCIS CRICK
 elucidated the structure of
DNA (genetic material)
 DNA contains coded
information which acts as a
blueprint for the transfer of
hereditary information from
generation to generation
 mutation as the raw
material for evolution

31.  A population is the smallest unit of evolution.
 Natural selection acts on individuals.
 However the evolutionary impact of natural selection is only
apparent in tracking how a population changes over time.
 Population Genetics emphasizes the extensive genetic variation
within populations and tracks the genetic make-up of populations
over time.
 Not all variation in a population is inheritable.
 Only the genetic component of variation is relevant to natural
selection.
 Many variable traits in a population result from the combined effect of
several genes.

32. Genetic equilibrium- allele frequencies
remain constant.
 Populations should be in a state of equilibrium
assuming:
 1. Large Population
 2. Random Mating
 3. No Migration
 4. No Mutation
 5. No natural selection occurs.

34.  Perfectly adapted organsim.
 Sharks
 Alligator
 Horseshoe Crab
 Stable envrionment.
 Water (Oceans)

35.  Speciation occurs relatively quickly with long
periods of equilibrium in between.
 Speciation = The formation of a new species due to
evolution.

37.  Evolution can occur without natural selection.
 Genetic Drift is a change in the gene pool due
to a random event.
 Example- Mount Saint Helens Eruption.
 If the event is catastrophic and all the
organisms are killed off = Mass extinction.

38.  = The formation of a new species due to evolution.
 Reproductive Isolation- Can result in speciation. It
is the separation of members of a species due to
some barrier.
 Islands
 Mountains
 Roads
 Oil Pipes

39. •Speciation occurs only
with the evolution of
reproductive barriers
between the isolated
population and its parent
population.
•If speciation occurs
during geographic
separation, the new
species will not breed
with its ancestral
population, even if the
two populations should
come back into contact.

40.  Allopatric Speciation
 A population forms a
new species while
geographically isolated
from its parent
population.
 Sympatric Speciation
 A small population
becomes a new species
in the midst of a parent
population

41.  Does not widely occur among
animals but may account for
over 25% of all plant species.

42. Notice how the hybrid
bread wheat has a set
of chromosomes from
each of its ancestors:
T. monococcum (AA),
Triticum (BB), T.
turgidum (AA BB), T.
tauschii (DD)
What can you notice about
T. aestivum that might
make it a good hybrid and
the most important wheat
species today?

43.  Convergent Evolution- Organisms of different
ancestry adapting to a similar environment.
 Produces homologous Structures.
 Example: bats and Butterflies wings.
 Dolphin
 Penguin
 Shark
 Divergent Evolution- Organisms of common
ancestry adapting to diverse environments.
 Produces analogous Structures.
 Example: Human Arm and Bird wing.

44. 1. Genetic Drift
Def: A change in the gene pool of a small population due to chance.
The best measure of Darwinian fitness is the number of fertile
offspring an individual leaves.

45. 2. Gene Flow
Def: The genetic exchange with another population.
3. Mutations
 A change in an organism’s DNA sequence.
 Ultimate source of genetic variability.
4. Natural Selection
 Directional Selection (selecting in favor of an extreme phenotype)
 Disruptive (Diversifying) Selection (leads to a balance between two or
more contrasting phenotypic forms)
 Stabilizing Selection (maintains variation in a narrow range)

46. •Resistant Genes
•Immediate
Benefits
•Long term
Disaster
•Evolution direct
connection to
daily lives

47.  Def: Major biological changes
evident in fossil record.
 CONTRAST:
MICROEVOLUTION
 Speciation
 Nonbranching evolution
(transform a population
enough for it to be designated
a new species.)
 Branching evolution (splits a
lineage into two or more
species)

48.  Ernst Mayr
 Studied the diversity of birds in New Guinea (1927)
 Biological species concept
 Species = “groups of interbreeding natural populations that are
reproductively isolated from other such groups.”
 Reproductive isolation blocks exchange of genes between species and
keeps their gene pools separate.
• Reproductive barriers between species
• Zygote: fertilized egg
• Pre-zygotic (factors that impede
mating between species or hinder
fertilization of eggs if mating is
attempted)
• Post-zygotic (mechanisms that
operate should interspecies mating
actually occur and form hybrid
zygotes)

49. Isolating Mechanisms
Courtship
Sterile

50. Spurts of
Slow relatively
adaptations rapid
change

51. Flowchart
Section 17-4
Species
that are
Unrelated Related
form in under under in in
Similar Intense
Inter-relationshiops Small Different
environments environmental
populations environments
pressure
can undergo can undergo can undergo can undergo can undergo
Coevolution Convergent Punctuated Adaptive
Extinction
evolution equilibrium radiation

52.  Systematics
 Reconstructing evolutionary history
 Radioactive dating = tool
 The study of biological diversity: past and present
 Taxonomy
 Identification, naming and classification of species
 Pioneer: Carolus Linnaeus (1707-1778)
 Binomial Nomenclature
 Homo sapien

53. Hierarchical
Classification
Which step is more
specific?
Class or Genus?
How is Domain
Eukarya different from
Bacteria and Archaea?

54. •Evolutionary
history of a
species.
•Tree is based on
homologous
structures, NOT
analogous.
•Two species will
have more
common
nucleotide
sequences based
on how recently
they branched
from their
common ancestor.

55. The Computer
Age

56. Archaea-
Eubacteria bacteria
?