Download Chapter 15 - Evolution

Chapter 22
Descent with Modification:
A Darwinian View of Life
PowerPoint® Lecture Presentations for
Biology
Eighth Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Overview: Endless Forms Most Beautiful
•
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
•
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
•
Three observations about life
–
Organisms are suited for life in their environments
–
Organisms share many characteristics
–
Organisms show a great diversity
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Figure 22.1 How can this beetle survive in the desert, and what is it doing?
Fig. 22-5
GREAT
BRITAIN
EUROPE
NORTH
AMERICA
ATLANTIC
OCEAN
The
Galápagos
Islands
AFRICA
Pinta
Genovesa
Equator
Marchena
Santiago
Fernandina
Isabela
Daphne
Islands
Pinzón
Santa
Santa
Cruz
Fe
Florenza
SOUTH
AMERICA
AUSTRALIA
PACIFIC
OCEAN
San
Cristobal
Cape of
Good Hope
Tasmania
Española
Cape Horn
Tierra del Fuego
New
Zealand
Fig. 22-6
(a) Cactus-eater
•
In reassessing his
observations,
Darwin perceived
adaptation to the
environment and
the origin of new
species as closely
related processes
(c) Seed-eater
(b) Insect-eater
The Origin of Species
•
Darwin developed two main ideas:
–
Descent with modification explains life’s unity and diversity
–
Natural selection is a cause of adaptive evolution
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Artificial Selection, Natural Selection, and
Adaptation
• Darwin noted that
humans have
modified other species
by selecting and
breeding individuals
with desired traits, a
process called
artificial selection
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Artificial Selection, Natural Selection, and
Adaptation
• Darwin then described four observations of nature and
from these drew two inferences
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 22-10
•
Observation #1: Members of a population often vary greatly in their traits
• Observation #2: Traits are inherited from
parents to offspring
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 22-11
Observation #3: All species are capable of producing
more offspring than the environment can support
Spore
cloud
• Observation #4: Owing to lack of food or other
resources, many of these offspring do not survive
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
• 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
• Inference #2: This unequal ability of individuals
to survive and reproduce will lead to the
accumulation of favorable traits in the
population over generations
• This process explains the match between
organisms and their environment
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Natural Selection:
A Summary
•
Individuals with certain
heritable characteristics
survive and reproduce at
a higher rate than other
individuals
•
Natural selection
increases the adaptation
of organisms to their
environment over time
•
If an environment
changes over time,
natural selection may
result in adaptation to
these new conditions and
may give rise to new
species
Natural Selection: A Summary
• Note that individuals do not evolve; populations
evolve over time!!!!!!!
• Natural selection can only increase or
decrease heritable traits in a population
• Adaptations vary with different environments
• What is the ultimate source of genetic
variation?
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Concept 22.3: Evolution is supported by an
overwhelming amount of scientific evidence
• One example includes the evolution of drugresistant HIV
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
•
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
•
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
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
The Fossil
Record
0
2
•
•
The fossil
record
provides
evidence of
the extinction
of species, the
origin of new
groups, and
changes within
groups over
time
The red dot
shows change
over time in
the location
and angle of
the spines
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
Fig. 22-16
•
•
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
(a) Pakicetus (terrestrial)
(b) Rhodocetus (predominantly aquatic)
Pelvis and
hind limb
(c) Dorudon (fully aquatic)
Pelvis and
hind limb
(d) Balaena
(recent whale ancestor)
• Vestigial structures are remnants of features that served
important functions in the organism’s ancestors
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
• Homology is similarity resulting from common
ancestry
Humerus
Radius
Ulna
Carpals
Metacarpals
Phalanges
Human
Cat
Whale
Bat
• 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
Pharyngeal
pouches
Post-anal
tail
Chick embryo (LM)
Human embryo
Fig. 21-11
Human chromosome 16
DNA sequences very similar to large
blocks of human chromosome 16 are
found on mouse chromosomes 7, 8, 16,
and 17. This suggests that the DNA
sequence in each block has stayed
together in the mouse and human
lineages since the time they diverged
from a common ancestor.
Blocks of DNA
sequence
Blocks of similar sequences in four mouse chromosomes:
7
8
16
17
Duplication, rearrangement, and
mutation of DNA contribute to genome
evolution
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Concept 21.6: Comparing genome sequences
provides clues to evolution and development
•
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
•
Fig. 21.15 – This tree diagram shows the ancient divergence of bacteria,
archaea, and eukaryotes. A portion of the eukaryote lineage is expanded in
the inset to show the more recent divergence of three mammalian species.
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Fig. 21-15
Bacteria
Most recent
common
ancestor
of all living
things
Eukarya
Archaea
4
3
2
Billions of years ago
1
0
Chimpanzee
Human
Mouse
70
60
50
40
30
20
Millions of years ago
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10
0
Fig. 22-20
•
•
•
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
Sugar
glider
NORTH
AMERICA
AUSTRALIA
The ability to glide evolved
independently in these two
distantly related groups of
mammals
Flying
squirrel
Fig. 26-7
An elongated body, enlarged front paws, small eyes, and a pad of thickened skin
that protects a tapered nose all evolved independently in the marsupial Australian
“mole” (top) and a eutherian North American mole (bottom).
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
•
Earth’s continents were formerly united in a single large continent called
Pangaea, but have since separated by continental drift (this term outdated,
plate tectonics is now the proper term)
•
An understanding of continent movement and modern distribution of species
allows us to predict when and where different groups evolved
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Mid Ocean Ridge
Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings