Download AP BIOLOGY Big Idea #1 * Part A * Part #4

AP BIOLOGY
Big Idea #1 – Part A – Section #4
Evolution is Supported by
Scientific Evidence
Concept 22.3: 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
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Direct Observations of Evolutionary Change
• Two examples provide evidence for natural
selection: the effect of differential predation on
guppy populations and the evolution of drugresistant HIV
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Predation and Coloration in Guppies : Scientific
Inquiry
John Endler has studied the effects of predators
on wild guppy populations
• Brightly colored males are more attractive to
females
• However, brightly colored males are more
vulnerable to predation
• Guppy populations in pools with fewer
predators had more brightly colored males
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Fig. 22-13
EXPERIMENT
Predator: Killifish; preys
mainly on juvenile
guppies (which do not
express the color genes)
Experimental
transplant of
guppies
Pools with
killifish,
but no
guppies prior
to transplant
Guppies: Adult males have
brighter colors than those
in “pike-cichlid pools”
Predator: Pike-cichlid; preys mainly on adult guppies
Guppies: Adult males are more drab in color
than those in “killifish pools”
RESULTS
12
Number of
colored spots
12
10
8
6
4
2
0
Source
population
Transplanted
population
10
8
6
4
2
0
Source
population
Transplanted
population
Fig. 22-13a
EXPERIMENT
Predator: Killifish; preys
mainly on juvenile
guppies (which do not
express the color genes)
Guppies: Adult males have
brighter colors than those
in “pike-cichlid pools”
Experimental
transplant of
guppies
Pools with
killifish,
but no
guppies prior
to transplant
Predator: Pike-cichlid; preys mainly on adult guppies
Guppies: Adult males are more drab in color
than those in “killifish pools”
Fig. 22-13b
RESULTS
12
Number of
colored spots
12
10
8
6
4
2
0
Source
Transplanted
population population
10
8
6
4
2
0
Source
Transplanted
population population
• Endler transferred brightly colored guppies
(with few predators) to a pool with many
predators
• As predicted, over time the population became
less brightly colored
• Endler also transferred drab colored guppies
(with many predators) to a pool with few
predators
• As predicted, over time the population became
more brightly colored
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
The Evolution of Drug-Resistant HIV
• The use of drugs to combat HIV selects for
viruses resistant to these drugs
• HIV uses the enzyme reverse transcriptase to
make a DNA version of its own RNA genome
• The drug 3TC is designed to interfere and
cause errors in the manufacture of DNA from
the virus
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
• Some individual HIV viruses have a variation
that allows them to produce DNA without errors
• These viruses have a greater reproductive
success and increase in number relative to the
susceptible viruses
• The population of HIV viruses has therefore
developed resistance to 3TC
• The ability of bacteria and viruses to evolve
rapidly poses a challenge to our society
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 22-14
100
Patient
No. 1
Patient No. 2
75
50
Patient No. 3
25
0
0
2
4
6
Weeks
8
10
12
• 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
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The Fossil Record
• The fossil record provides evidence of the
extinction of species, the origin of new groups,
and changes within groups over time
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Fig. 22-15
0
2
4
4
6
4 Bristolia insolens
8
3 Bristolia bristolensis
10
12
3
2 Bristolia harringtoni
14
16
18 1 Bristolia mohavensis
3
2
1
Latham Shale dig site, San
Bernardino County, California
Depth (meters)
Fig. 22-15b
12
2
Bristolia harringtoni
14
16
18 1 Bristolia mohavensis
2
1
Latham Shale dig site, San
Bernardino County, California
Fig. 22-15c
0
4
3
Depth (meters)
2
4
6
4 Bristolia insolens
8
3 Bristolia bristolensis
10
• The Darwinian view of life predicts that
evolutionary transitions should leave signs in
the fossil record
• Paleontologists have discovered fossils of
many such transitional forms
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Fig. 22-16
(a) Pakicetus (terrestrial)
(b) Rhodocetus (predominantly aquatic)
Pelvis and
hind limb
(c) Dorudon (fully aquatic)
Pelvis and
hind limb
(d) Balaena
(recent whale ancestor)
Fig. 22-16ab
(a) Pakicetus (terrestrial)
(b) Rhodocetus (predominantly aquatic)
Fig. 22-16cd
Pelvis and
hind limb
(c) Dorudon (fully aquatic)
Pelvis and
hind limb
(d) Balaena
(recent whale ancestor)
Homology
• Homology is similarity resulting from common
ancestry
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Anatomical and Molecular Homologies
• Homologous structures are anatomical
resemblances that represent variations on a
structural theme present in a common ancestor
Comparative embryology reveals
anatomical homologies not visible in adult
organisms
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 22-17
Humerus
Radius
Ulna
Carpals
Metacarpals
Phalanges
Human
Cat
Whale
Bat
Fig. 22-18
Pharyngeal
pouches
Post-anal
tail
Chick embryo (LM)
Human embryo
Fig. 22-18a
Pharyngeal
pouches
Post-anal
tail
Chick embryo (LM)
Fig. 22-18b
Pharyngeal
pouches
Post-anal
tail
Human embryo
• Vestigial structures are remnants of features
that served important functions in the
organism’s ancestors
• Examples of homologies at the molecular level
are genes shared among organisms inherited
from a common ancestor
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Homologies and “Tree Thinking”
• The Darwinian concept of an evolutionary
tree of life can explain homologies
• Evolutionary trees are hypotheses about the
relationships among different groups
• Evolutionary trees can be made using different
types of data, for example, anatomical and
DNA sequence data
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 22-19
Branch point
(common ancestor)
Lungfishes
Amphibians
1
Mammals
2
Tetrapod limbs
Amnion
Lizards
and snakes
3
4
Homologous
characteristic
Crocodiles
Ostriches
6
Feathers
Hawks and
other birds
Birds
5
Convergent Evolution
• 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
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 22-20
Sugar
glider
NORTH
AMERICA
AUSTRALIA
Flying
squirrel
Biogeography
• Darwin’s observations of biogeography, the
geographic distribution of species, formed an
important part of his theory of evolution
• Islands have many endemic species that are
often closely related to species on the nearest
mainland or island
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• 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
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What Is Theoretical About Darwin’s View of Life?
• In science, a theory accounts for many
observations and data and attempts to explain
and integrate a great variety of phenomena
• 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
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 22-UN1
Observations
Individuals in a population
vary in their heritable
characteristics.
Organisms produce more
offspring than the
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.
Fig. 22-UN2
Fig. 22-UN3
You should now be able to:
1. Describe the contributions to evolutionary
theory made by Linnaeus, Cuvier, Lyell,
Lamarck, Malthus, and Wallace
2. Describe Lamarck’s theories, and explain why
they have been rejected
3. Explain what Darwin meant by “descent with
modification”
4. List and explain Darwin’s four observations
and two inferences
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5. Explain why an individual organism cannot
evolve
6. Describe at least four lines of evidence for
evolution by natural selection
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings