Artificial Selection and Direct Observation

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This presentation is about the theories on evolution and an overview of artificial selection and direct observation. Evolution is a change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes that are passed on from parent to offspring during reproduction.

1. CAMPBELL BIOLOGY IN FOCUS
Urry • Cain • Wasserman • Minorsky • Jackson • Reece
19
Descent with
Lecture Presentations by
Kathleen Fitzpatrick and Nicole Tunbridge
© 2014 Pearson Education, Inc.

2. Overview: Endless Forms Most Beautiful
 Lepidopteran insects (moths and butterflies) have
many features in common including a juvenile
feeding stage called a caterpillar
 Lepidopteran species also have many features that
are distinct from each other in both the caterpillar
and adult forms
© 2014 Pearson Education, Inc.

3.  Lepidopterans illustrate three key observations
about life
 The fit between organisms and their environment
 The shared characteristics (unity) of life
 The diversity of life
© 2014 Pearson Education, Inc.

4.  A new era of biology began in 1859 when Charles
Darwin published The Origin of Species
 The Origin of Species focused biologists’ attention
on the great diversity of organisms
© 2014 Pearson Education, Inc.

5.  Darwin noted that current species are descendants
of ancestral species
 Evolution can be defined by Darwin’s phrase
descent with modification
 Evolution can be viewed as both a pattern and a
process
© 2014 Pearson Education, Inc.

6. Concept 19.1: The Darwinian revolution
challenged traditional views of a young Earth
inhabited by unchanging species
 Darwin’s revolutionary ideas had deep historical roots
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7. Scala Naturae and Classification of Species
 The Greek philosopher Aristotle viewed species as
fixed and arranged them on a scala naturae
 The Old Testament holds that species were
individually designed by God and therefore perfect
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8.  Carolus Linnaeus interpreted organismal adaptations
as evidence that the Creator had designed each
species for a particular purpose
 Linnaeus was the founder of taxonomy, the branch
of biology concerned with classifying organisms
 He developed the binomial format for naming
species (for example, Homo sapiens)
© 2014 Pearson Education, Inc.

9. Ideas About Change over Time
 The study of fossils helped to lay the groundwork
for Darwin’s ideas
 Fossils are remains or traces of organisms from
the past, usually found in sedimentary rock, which
appears in layers or strata
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10. Figure 19.3
Younger stratum
with more recent
fossils
Older stratum
with older fossils
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11.  Paleontology, the study of fossils, was largely
developed by French scientist Georges Cuvier
 Cuvier speculated that each boundary between
strata represents a catastrophe that destroyed
many species
© 2014 Pearson Education, Inc.

12.  Geologists James Hutton and Charles Lyell
perceived that changes in Earth’s surface can result
from slow, continuous actions still operating today
 Lyell further proposed that the mechanisms of
change are constant over time
 This view strongly influenced Darwin’s thinking
© 2014 Pearson Education, Inc.

13. Lamarck’s Hypothesis of Evolution
 Lamarck hypothesized that species evolve through
use and disuse of body parts and the inheritance of
acquired characteristics
 The mechanisms he proposed are unsupported by
evidence
© 2014 Pearson Education, Inc.

14. Concept 19.2: Descent with modification by
natural selection explains the adaptations of
organisms and the unity and diversity of life
 Some doubt about the permanence of species
preceded Darwin’s ideas
© 2014 Pearson Education, Inc.

15. Darwin’s Research
 As a boy and into adulthood, Charles Darwin had a
consuming interest in nature
 Darwin first studied medicine (unsuccessfully) and
then theology at Cambridge University
 After graduating, he took an unpaid position as
naturalist and companion to Captain Robert FitzRoy
for a five-year around-the-world voyage on the
Beagle
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16. The Voyage of the Beagle
 During his travels on the Beagle, Darwin collected
specimens of South American plants and animals
 He observed that fossils resembled living species
from the same region, and living species resembled
other species from nearby regions
 He experienced an earthquake in Chile and observed
the uplift of rocks
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17.  Darwin was influenced by Lyell’s Principles of
Geology and thought that Earth was more than
6,000 years old
 His interest in geographic distribution of species was
kindled by a stop at the Galápagos Islands west of
South America
 He hypothesized that species from South America
had colonized the Galápagos and speciated on the
islands
© 2014 Pearson Education, Inc.

18. Figure 19.5c
The PACIFIC
Galápagos Pinta OCEAN
Islands
Genovesa
Marchena Equator
Santiago
Daphne
Islands
Pinzón
Fernandina
Isabela Santa Santa
Cruz Fe San
Cristobal
0 20 40 Florenza Española
Kilometers
© 2014 Pearson Education, Inc.

19. Darwin’s Focus on Adaptation
 In reassessing his observations, Darwin perceived
adaptation to the environment and the origin of
new species as closely related processes
 From studies made years after Darwin’s voyage,
biologists have concluded that this is what
happened to the Galápagos finches
© 2014 Pearson Education, Inc.

20. Figure 19.6
(a) Cactus-eater (c) Insect-eater
(b) Seed-eater
© 2014 Pearson Education, Inc.

21.  In 1844, Darwin wrote an essay on natural selection
as the mechanism of descent with modification but
did not introduce his theory publicly
 Natural selection is a process in which individuals
with favorable inherited traits are more likely to
survive and reproduce
 In June 1858, Darwin received a manuscript from
Alfred Russell Wallace, who had developed a theory
of natural selection similar to Darwin’s
 Darwin quickly finished The Origin of Species and
published it the next year
© 2014 Pearson Education, Inc.

22. Ideas from The Origin of Species
 Darwin explained three broad observations about life
 The unity of life
 The diversity of life
 The match between organisms and their environment
© 2014 Pearson Education, Inc.

23. Descent with Modification
 Darwin never used the word evolution in the first
edition of The Origin of Species
 The phrase descent with modification summarized
Darwin’s perception of the unity of life
 The phrase refers to the view that all organisms are
related through descent from an ancestor that lived
in the remote past
© 2014 Pearson Education, Inc.

24.  In the Darwinian view, the history of life is like a tree
with branches representing life’s diversity
 Fossils of extinct species help to “fill in” the
morphological gaps between present-day groups
© 2014 Pearson Education, Inc.

25. Figure 19.8
© 2014 Pearson Education, Inc.

26. Figure 19.9
Hyracoidea
(Hyraxes)
Sirenia
(Manatees
† Moeritherium and relatives)
† Barytherium
† Deinotherium
† Mammut
† Platybelodon
† Stegodon
† Mammuthus
Elephas maximus
(Asia)
Loxodonta africana
(Africa)
Loxodonta cyclotis
(Africa)
60 34 24 5.5 2 104 0
Millions of years ago Years ago
© 2014 Pearson Education, Inc.

27. Figure 19.9a
Hyracoidea
(Hyraxes)
Sirenia
(Manatees
† Moeritherium and relatives)
† Barytherium
†Deinotherium
† Mammut
© 2014 Pearson Education, Inc.

28. Figure 19.9b
† Platybelodon
† Stegodon
† Mammuthus
Elephas maximus
(Asia)
Loxodonta africana
(Africa)
Loxodonta cyclotis
(Africa)
60 34 24 5.5 2 104 0
Millions of years ago Years ago
© 2014 Pearson Education, Inc.

29. Artificial Selection, Natural Selection, and
 Darwin noted that humans have modified other
species by selecting and breeding individuals with
desired traits, a process called artificial selection
 Darwin argued that a similar process occurs in nature
© 2014 Pearson Education, Inc.

30. Figure 19.10
Cabbage
Selection for
apical (tip) bud
Brussels
sprouts Selection for Selection Broccoli
axillary (side) for flowers
buds and stems
Selection
for stems
Selection
for leaves
Kale Wild mustard Kohlrabi
© 2014 Pearson Education, Inc.

31.  Darwin drew two inferences from two observations
 Observation #1: Members of a population often vary
in their inherited traits
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32.  Observation #2: All species can produce more
offspring than the environment can support, and
many of these offspring fail to survive and reproduce
© 2014 Pearson Education, Inc.

34.  Inference #1: Individuals whose inherited traits
give them a higher probability of surviving and
reproducing in a given environment tend to leave
more offspring than other individuals
© 2014 Pearson Education, Inc.

35.  Inference #2: This unequal ability of individuals to
survive and reproduce will lead to the accumulation
of favorable traits in the population over
generations
© 2014 Pearson Education, Inc.

36.  Darwin was influenced by Thomas Malthus, who
noted the potential for human population to increase
faster than food supplies and other resources
 If some heritable traits are advantageous, these will
accumulate in a population over time, and this will
increase the frequency of individuals with these
traits
 This process explains the match between
organisms and their environment
© 2014 Pearson Education, Inc.

37. Natural Selection: A Summary
 Individuals with certain heritable traits survive and
reproduce at a higher rate than other individuals
 Over time, natural selection increases the match
between organisms and their environment
 If an environment changes over time, natural
selection may result in adaptation to these new
conditions and may give rise to new species
© 2014 Pearson Education, Inc.

39.  Note that individuals do not evolve; populations
evolve over time
 Natural selection can only increase or decrease
heritable traits that vary in a population
 Adaptations vary with different environments
© 2014 Pearson Education, Inc.

40. Concept 19.3: Evolution is supported by an
overwhelming amount of scientific evidence
 New discoveries continue to fill the gaps identified
by Darwin in The Origin of Species
 There are four types of data that document the
pattern of evolution
 Direct observations
 Homology
 The fossil record
 Biogeography
© 2014 Pearson Education, Inc.

41. Direct Observations of Evolutionary Change
 Two examples provide evidence for natural selection:
natural selection in response to introduced plant
species and the evolution of drug-resistant bacteria
© 2014 Pearson Education, Inc.

42. Natural Selection in Response to Introduced Plant
 Soapberry bugs use their “beak” to feed on seeds
within fruits
 In southern Florida soapberry bugs feed on balloon
vine with larger fruit; they have longer beaks
 In central Florida they feed on goldenrain tree with
smaller fruit; they have shorter beaks
 Correlation between fruit size and beak size has
also been observed in Louisiana, Oklahoma, and
Australia
© 2014 Pearson Education, Inc.

43.  In all cases, beak size has evolved in populations
that feed on introduced plants with fruits that are
smaller or larger than the native fruits
 These cases are examples of evolution by natural
selection
 In Florida this evolution in beak size occurred in less
than 35 years
© 2014 Pearson Education, Inc.

44. Figure 19.14
Field Study Results
10 On native species, Beak
8 balloon vine
6 (southern Florida)
Number of individuals
4
2
0
Museum-specimen average
10 On introduced
Soapberry bug with beak 8 species,
inserted in balloon vine 6 goldenrain tree
fruit 4 (central Florida)
2
0
6 7 8 9 10 11
Beak length (mm)
© 2014 Pearson Education, Inc.

45. The Evolution of Drug-Resistant Bacteria
 The bacterium Staphylococcus aureus is commonly
found on people’s skin or in their nasal passages
 Methicillin-resistant S. aureus (MRSA) strains are
dangerous pathogens
 S. aureus became resistant to penicillin in 1945,
two years after it was first widely used
 S. aureus became resistant to methicillin in 1961,
two years after it was first widely used
© 2014 Pearson Education, Inc.

46.  Methicillin works by inhibiting a protein used by
bacteria in their cell walls
 MRSA bacteria use a different protein in their cell
walls
 When exposed to methicillin, MRSA strains are more
likely to survive and reproduce than nonresistant
S. aureus strains
 MRSA strains are now resistant to many antibiotics
© 2014 Pearson Education, Inc.

47. Figure 19.15
2,750,000 1
250,000 base pairs
400
Annual hospital admissions
2,500,000
350
with MRSA (thousands)
Chromosome map
of S. aureus clone USA300 500,000 300
Key to adaptations 250
2,250,000
Methicillin resistance 200
Ability to colonize hosts 750,000 150
Increased disease severity
100
2,000,000 Increased gene exchange
(within species) and 50
toxin production 1,000,000 0
’93 ’94 ’95 ’96 ’97 ’98 ’99 ’00 ’01 ’02 ’03 ’04 ’05
1,750,000 Year
1,250,000
1,500,000
© 2014 Pearson Education, Inc.

48. Figure 19.15a
2,750,000 1
250,000 base pairs
2,500,000
Chromosome map
of S. aureus clone USA300 500,000
Key to adaptations
2,250,000
Methicillin resistance
Ability to colonize hosts 750,000
Increased disease severity
2,000,000 Increased gene exchange
(within species) and
toxin production 1,000,000
1,750,000
1,250,000
1,500,000
© 2014 Pearson Education, Inc.

49. Figure 19.15b
400
Annual hospital admissions
350
with MRSA (thousands)
300
250
200
150
100
50
0
’93 ’94 ’95 ’96 ’97 ’98 ’99 ’00 ’01 ’02 ’03 ’04 ’05
Year
© 2014 Pearson Education, Inc.

50.  Natural selection does not create new traits, but
edits or selects for traits already present in the
population
 The local environment determines which traits will
be selected for or selected against in any specific
population
© 2014 Pearson Education, Inc.

51.  Evolution is a process of descent with modification
 Related species can have characteristics with
underlying similarity that function differently
 Homology is similarity resulting from common
ancestry
© 2014 Pearson Education, Inc.

52. Anatomical and Molecular Homologies
 Homologous structures are anatomical
resemblances that represent variations on a
structural theme present in a common ancestor
© 2014 Pearson Education, Inc.

54.  Comparative embryology reveals anatomical
homologies not visible in adult organisms
 Vestigial structures are remnants of features that
served important functions in the organism’s
ancestors
© 2014 Pearson Education, Inc.

56.  Examples of homologies at the molecular level are
genes shared among organisms inherited from a
common ancestor
 Homologous genes can be found in organisms as
dissimilar as humans and bacteria
© 2014 Pearson Education, Inc.

57. A Different Cause of Resemblance: Convergent
 Convergent evolution is the evolution of similar, or
analogous, features in distantly related groups
 Analogous traits arise when groups independently
adapt to similar environments in similar ways
 Convergent evolution does not provide information
about ancestry
© 2014 Pearson Education, Inc.

59. The Fossil Record
 The fossil record provides evidence of
 The extinction of species
 The origin of new groups
 Changes within groups over time
© 2014 Pearson Education, Inc.

60. Figure 19.19
Most mammals Cetaceans and even-toes ungulates
(a) Canis (dog) (b) Pakicetus (c) Sus (pig) (d) Odocoileus (deer)
© 2014 Pearson Education, Inc.

61.  Fossils can document important transitions
 For example, the transition from land to sea in the
ancestors of cetaceans
© 2014 Pearson Education, Inc.

62. Figure 19.20
Other even-toed
ungulates
Hippopotamuses
†Pakicetus
†Rodhocetus
Common
ancestor †Dorudon
of cetaceans
Living
cetaceans
70 60 50 40 30 20 10 0 Key Pelvis Tibia
Millions of years ago Femur Foot
© 2014 Pearson Education, Inc.

63. Figure 19.20a
†Pakicetus
Common
ancestor
of cetaceans †Rodhocetus
†Dorudon
Living
cetaceans
50 40 30 20 10 0 Key Pelvis Tibia
Millions of years ago Femur Foot
© 2014 Pearson Education, Inc.

65.  Biogeography, the geographic distribution of
species, provides evidence of evolution
 Earth’s continents were formerly united in a single
large continent called Pangaea but have since
separated by continental drift
 An understanding of continent movement and
modern distribution of species allows us to predict
when and where different groups evolved
© 2014 Pearson Education, Inc.

66.  Endemic species are species that are not found
anywhere else in the world
 Islands have many endemic species that are often
closely related to species on the nearest mainland
or island
 Darwin explained that species on islands gave rise to
new species as they adapted to new environments
© 2014 Pearson Education, Inc.

67. What Is Theoretical About Darwin’s View of Life?
 In science, a theory accounts for many observations
and explains and integrates a great variety of
phenomena
 The predictions of a scientific theory must stand up
to continual testing by experimentation and
observation
 Darwin’s theory of evolution by natural selection
integrates diverse areas of biological study and
stimulates many new research questions
 Ongoing research adds to our understanding of
evolution
© 2014 Pearson Education, Inc.

68. Figure 19.UN02a
Guppies
transplanted
Pools with
pike-cichlids Pools with killifish,
and guppies but no guppies
prior to transplant
© 2014 Pearson Education, Inc.

69. Figure 19.UN02b
12 12
Area of colored
10 10
colored spots
spots (mm2)
Number of
8 8
6 6
4 4
2 2
0 0
Source Transplanted Source Transplanted
population population population population
© 2014 Pearson Education, Inc.

70. Figure 19.UN03
Observations
Individuals in a population Organisms produce more
vary in their heritable offspring than the
characteristics. environment can support.
Inferences
Individuals that are well suited
to their environment tend to leave more
offspring than other individuals.
and
Over time, favorable traits
accumulate in the population.
© 2014 Pearson Education, Inc.

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