You Light Up My Life

1
The Evidence for Evolution
Chapter 21 and 22
2
Evolutionary Theories

• Widely used to interpret the past and present,
  and even to predict the future
• Reveal connections between the geological record,
  fossil record, and organismal diversity

3
Confounding Evidence

• Biogeography
• Comparative anatomy/morphology
• Geologic discoveries

4
Biogeography

• Study of patterns in the geographic distribution
  of species
• Size of the known world expanded enormously in
  the 15th century
• Discovery of new organisms in previously unknown
  places could not be explained by accepted beliefs
• How did species get from center of creation to
  all these places?

5
South American Rhea
Fig. 16-2a, p.238
6
Australian Emu
Fig. 16-2b, p.238
7
African Ostrich
Fig. 16-2c, p.238
8
American Southwest
Fig. 16-2d, p.238
9
Southwestern Africa
Fig. 16-2e, p.238
10
Comparative Morphology

• Study of similarities and differences in body
  plans of major groups
• Puzzling patterns
• Animals as different as whales and bats have
  similar bones in forelimbs
• Some parts seem to have no function

11
Ancient Whale
fossilized ankle bone
Fig. 16-3b, p.239
12
coccyx
ankle bone
Fig. 16-3a, p.239
13
Geological Discoveries

• Similar rock layers throughout world
• Certain layers contain fossils
• Deeper layers contain simpler fossils
• More intricate as layers get more shallow
• Fossils from shallow layers seem to be related to
  known species

14
19th Century - New Theories

• Scientists attempt to reconcile evidence of
  change with traditional belief in a single
  creation event
• Two examples
• Georges Cuvier - multiple catastrophes
• Jean Lamark - inheritance of acquired
  characteristics (giraffes, muscles)

15
Fig. 20.1.a
16
Fig. 20.1.b
17
Charles Darwin

• Enjoyed outdoors as a childhunting, fishing,
  bird watching, etc.
• Father forced him to go to medical school
  (sickened him)
• Got a degree in Theology
• Spent time with natural history faculty
• John Henslowbotanist noticed his
  potentialBeagle

18
Darwins Voyage

• At age 22, Charles Darwin began a five-year,
  round-the-world voyage aboard the Beagle
• In his role as ships naturalist he collected and
  examined the species that inhabited the regions
  the ship visited

19
Voyage of the Beagle
20
GalapagosIslands

• Volcanic islands far off coast of Ecuador
• All inhabitants are descended from species that
  arrived on islands from elsewhere

Isabela
21
Fig. 16-5e, p.241
22
Fig. 22.3
23
The Theory of Uniformity

• Lyells Principles of Geology
• Subtle, repetitive processes of change, had
  shaped Earth
• Challenged the view that Earth was only 6,000
  years old

24
Glyptodonts Armadillos

• In Argentina, Darwin observed fossils of extinct
  glyptodonts (very large)
• Resemble living armadilloslived in the same
  places armadillos live now
• Could they be ancestors of armadillos?
• Descent with modification

25
Fig. 16-6a, p.242
26
Fig. 16-6b, p.242
27
Malthus - Struggle to Survive

• Thomas Malthusclergyman and economist
• Wrote essay that Darwin read on his return to
  England
• Argued that as population size increases,
  resources dwindle, the struggle to live
  intensifies and conflict increases
• Sea star2,500,000 eggs a year
• Not all survive (predation, lack of resources)
• Darwinvariations in traits made some better able
  to survive and reproduce than others

28
Galapagos Finches

• Darwin observed finches with a variety of
  lifestyles and body forms
• On his return he learned that there were 13
  species
• He attempted to correlate variations in their
  traits with environmental challenges

29
Evidence of Natural Selection

• Darwins finches

30
Evidence of Natural Selection

• Evidence that natural selection alters beak shape

31
Fig. 22.14
32
Darwins Theory

• A population can change over time when
  individuals differ in one or more heritable
  traits that are responsible for differences in
  the ability to survive and reproduce

33
Alfred Wallace

• Naturalist who arrived at the same conclusions
  Darwin did
• Wrote to Darwin describing his views
• Prompted Darwin to finally present his ideas in a
  formal paper

34
On the Origin of Species

• Darwins book
• Published in 1859
• Laid out in great detail his evidence in support
  of the theory of evolution by natural selection

35
Darwins Key Observations

• 1) Populations have inherent reproductive
  capacity
• 2) No population can indefinitely grow (limiting
  factors)
• 3) Individuals end up competing for resources
• 4) Individuals have shared traits genes are pool
  of heritable information

36
Darwins Key Observations

• 5) Mutations give rise to new alleles
• 6) Some phenotypes are better than other for
  competition (fitness)
• 7) Natural selectionoutcome of variation in
  traits that allow individuals to survive and
  reproduceresults in adaptation

37
Fossils

• Recognizable evidence of ancient life
• Fossilized hard parts (most common)
• Teeth, bones, seeds
• Trace fossils (indirect evidence)
• Imprints of leaves, tracks, fossilized feces

38
Fossilization

• Organism becomes buried in ash or sediments
• Rapid burial and a lack of oxygen aid in
  preservation
• The organic remains become infused with metal and
  mineral ions
• Rare

39
p.259b
40
Opener
41
Fig. 17-2b, p.260
42
Fig. 21.11
43
Stratification

• Fossils are found in sedimentary rock
• Formed in layers
• Layers closest to the top formed most recently

44
Fig. 17-3, p.261
45
What Do Fossils Tell Us?

• As a result of mutations, natural selection, and
  drift, each species is a mosaic of ancestral and
  novel traits
• All species that ever evolved are related to one
  another by way of descent

46
Radiometric Dating

• Rate of isometric decay of atoms is relatively
  constant
• Half-lifethe time it takes for half of a
  quantity of a radioisotopes atoms to decay
• Can predict with great accuracy how old a fossil
  is

47
Fig. 21.9
48
Geologic Time Scale

• Archean eon (oldest interval)
• Proterozoic eon
• Paleozoic era
• Mesozoic era
• Cenozoic era (most recent)

• Boundaries based on abrupt transitions in fossil
  record
• Correspond to mass extinctions

49
Fig. 17-5, p.263
50
Macroevolution

• The large-scale patterns, trends, and rates of
  change among higher taxa

51
Continental Drift

• Idea that the continents were once joined and
  have since drifted apart
• Initially based on the shapes
• Pangea theoretical supercontinent

52
Evidence of Movement

• Same glacial deposits, coal seams, and basalt
  found in Africa India and Australia
• All these land masses hold fossils of
  Glossopteris (fern) and Lystrosaurus (mammal-like
  reptile)
• Plants nor reptiles could have crossed this vast
  of ocean
• Scientist suspect they evolved together on
  Gondwanna

53
Evidence of Movement

• Later was discovered that magnetic orientations
  in ancient rocks do not align with the magnetic
  poles
• Discovery of seafloor spreading provided a
  possible mechanism

54
Plate Tectonics

• Earths crust is fractured into plates
• Movement of plates is driven by upwelling of
  molten rock at mid-oceanic ridges
• As seafloor spreads, older rock is forced down
  into trenches

55
Forces of Change
island arc
oceanic crust
oceanic ridge
trench
continental crust
lithosphere (solid layer of mantle)
subducting plate
athenosphere (plastic layer of mantle)
hot spot
56
Changing Land Masses
10 mya
65 mya
260 mya
420 mya
57
Comparative Morphology

• Comparing body forms and structures of major
  lineages
• Homologous structuressimilarities in body parts
  that suggest common ancestry
• Morphological divergencechange from the body
  form of a common ancestor
• Produces homologous structures that may serve
  different functions

58
Fig. 21.14
59
Comparative Biochemistry

• Kinds and numbers of biochemical traits that
  species share is a clue to how closely they are
  related
• Can compare DNA, RNA, or proteins
• More similarity means species are more closely
  related

60
Fig. 17-15, p.271
61
Comparing Proteins

• Compare amino acid sequence of proteins produced
  by the same gene
• Human cytochrome c (a protein)
• Identical amino acids in chimpanzee protein
• Chicken protein differs by 18 amino acids
• Yeast protein differs by 56

62
Mitochondrial DNA

• mt DNA mutates quickly
• Inherited entirely from one parent (mother)
• Any changes due to mutations and not
  recombination
• Monitor change in eukaryotic populations

63
Speciation Natural Selection

• Natural selection can lead to speciation
• Speciation can also occur as a result of other
  microevolutionary processes
• Genetic drift
• Mutation

64
Morphology Species

• Morphological traits may not be useful in
  distinguishing species
• Members of same species may appear different
  because of environmental conditions
• Morphology can vary with age and sex
• Different species can appear identical

65
Variable Morphology
Grown in water
Grown on land
66
Fig. 21.15
67
Biological Species Concept

• Species are groups of interbreeding natural
  populations that are reproductively isolated from
  other such groups.
• - Ernst Mayr

68
Genetic Divergence

• Gradual accumulation of differences in the gene
  pools of populations
• Natural selection, genetic drift, and mutation
  can contribute to divergence
• Gene flow counters divergence

69
Reproductive Isolation

• Cornerstone of the biological species concept
• Speciation is the attainment of reproductive
  isolation
• Reproductive isolation arises as a by-product of
  genetic change

70
Fig. 17-18, p.273
71
Allopatric Speciation

• Speciation in geographically isolated populations
  
• Probably most common mechanism
• Some sort of barrier arises and prevents gene
  flow
• Effectiveness of barrier varies with species

72
Fig. 22.8
73
Extensive Divergence Prevents Inbreeding

• Species separated by geographic barriers will
  diverge genetically
• If divergence is great enough it will prevent
  inbreeding even if the barrier later disappears

74
Hawaiian Islands

• Volcanic origins, variety of habitats
• Adaptive radiations
• Honeycreepers - In absence of other bird species,
  they radiated to fill numerous niches
• Fruit flies (Drosophila) - 40 of fruit fly
  species are found in Hawaii

75
Fig. 17-20b, p.275
76
Speciation without a Barrier

• Sympatric speciation
• Species forms within the home range of the parent
  species
• Parapatric speciation
• Neighboring populations become distinct species
  while maintaining contact along a common border

77
Sympatric Speciation in African Cichlids

• Studied fish species in two lakes
• Species in each lake are most likely descended
  from single ancestor (mtDNA)
• No barriers within either lake
• Some ecological separation (food preferences) but
  species in each lake breed in sympatry

78
Fig. 22.15
79
Parapatric Speciation

• Adjacent populations evolve into distinct
  species while maintaining contact along a common
  border

T. barretti
hybrid zone
T. anophthalmus
80
Hybrids between these are sterile
81
Were All Related

• All species are related by descent
• Share genetic connections that extend back in
  time to the prototypical cell

82
Evolutionary Tree
83
Adaptive Radiation

• Burst of divergence
• Single lineage gives rise to many new species
• New species fill vacant adaptive zone
• Adaptive zone is way of life
• Honeycreepers

84
Adaptive Radiation
85
Extinction

• Irrevocable loss of a species
• Mass extinctions have played a major role in
  evolutionary history
• Fossil record shows 20 or more large-scale
  extinctions
• Reduced diversity is followed by adaptive
  radiation

86
Who Survives?

• Species survival is to some extent random
• Asteroids have repeatedly struck Earth destroying
  many lineages
• Changes in global temperature favor lineages that
  are widely distributed

87
Phylogeny

• The scientific study of evolutionary
  relationships among species

88
ANIMALS
PLANTS
arthropods
chordates
FUNGI
flowering plants
conifers
annelids
roundworms
sac fungi
club fungi
echinoderms
ginkgos
mollusks
cycads
horsetails
rotifers
zygospore- forming fungi
ferns
flatworms
cnidarians
lycophytes
bryophytes
chytrids
charophytes
sponges
chlorophytes
amoeboid protozoans
PROTISTS
choanoflagellates
(stramenopiles)
brown algae
alveolates
red algae
ciliates
chrysophytes
apicomplexans
oomycotes
dinoflagellates
crown of eukaryotes (rapid divergences)
euglenoids
slime molds
kinetoplatids
Parabasalids (e.g., Trichomonas)
ARCHAEA
BACTERIA
spirochetes
diplomonads
crenarchaeotes
euryarchaeotes
Gram-positive bacteria
chlamydias
cyanobacteria
korarchaeotes
Fig. 17-31, p.282