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Chapter 22: Descent with Modification: A Darwinian
View of Life
1. What do you know about evolution?
2. What is evolution?
- Gradual change over time
3. What is paleontology?
-Study of fossils
-Allows for relative dating - “older” or “younger” - depends on layer
Chapter 22: Descent with Modification: A Darwinian
View of Life
1. What do you know about evolution?
2. What is evolution?
3. What is paleontology?
4. What was Lamarck’s view?
- Inheritance of acquired characteristics
- Evolution within an organism’s lifetime – “use & disuse”
- Examples – Blacksmith, giraffe
- Viewed for 150 years as being wrong…but he could
be partially right! (epigenetics—inheritance of methylation)
5. What was Darwin’s view?
- Environment supplies selective pressure—struggle for
existence
- REPRODUCTION of the fittest
Figure 22.5 The voyage of HMS Beagle
England
EUROPE
NORTH
AMERICA
ATLANTIC
OCEAN
PACIFIC
OCEAN
Galápagos
Islands
HMS Beagle in port
SOUTH
AMERICA
AUSTRALIA
Andes
Darwin in 1840,
after his return
AFRICA
Cape of
Good Hope
Tasmania
Cape Horn
Tierra del Fuego
New
Zealand
Chapter 22: Descent with Modification: A Darwinian
View of Life
1. What do you know about evolution?
2. What is evolution?
3. What is paleontology?
4. What was Lamarck’s view?
- Inheritance of acquired characteristics
- Evolution within an organism’s lifetime – use & disuse
- Examples – Blacksmith, giraffe
5. What was Darwin’s view?
- Environment supplies selective pressure—struggle for
existence
- REPRODUCTION of the fittest
- Studied Galapagos finches
Figure 22.6 Beak variation in Galápagos finches
(a) Cactus eater. The long,
sharp beak of the cactus
ground finch (Geospiza
scandens) helps it tear
and eat cactus flowers
and pulp.
(c) Seed eater. The large ground
finch (Geospiza magnirostris)
has a large beak adapted for
cracking seeds that fall from
plants to the ground.
(b) Insect eater. The green warbler
finch (Certhidea olivacea) uses its
narrow, pointed beak to grasp insects.
Chapter 22: Descent with Modification: A Darwinian
View of Life
1. What do you know about evolution?
2. What is evolution?
3. What is paleontology?
4. What was Lamarck’s view?
- Inheritance of acquired characteristics
- Evolution within an organism’s lifetime – use & disuse
- Examples – Blacksmith, giraffe
5. What was Darwin’s view?
- Environment supplies selective pressure—struggle for
existence
- REPRODUCTION of the fittest
- not SOTF
- Studied Galapagos finches
- 1859 – The Origin of Species – 2 main points
- Descent with Modification from common ancestor
- Natural selection is the mechanism of evolution
Figure 22.7 Descent with modification
Sirenia
Hyracoidea (Manatees
(Hyraxes) and relatives)
Elephas Loxodonta Loxodonta
cyclotis
maximus africana
(Africa)
(Asia)
(Africa)
Chapter 22: Descent with Modification: A Darwinian
View of Life
1. What do you know about evolution?
2. What is evolution?
3. What is paleontology?
4. What was Lamarck’s view?
5. What was Darwin’s view?
6. Summarizing Darwin’s view
- Natural selection = differential reproductive success
- Natural selection occurs through interactions between
the environment and the variability among individual
organisms in a population
Figure 22.9 Variation in a population
Figure 22.11 Camouflage as an example of
evolutionary adaptation
(a) A flower mantid
in Malaysia
(b) A stick mantid
in Africa
Chapter 22: Descent with Modification: A Darwinian
View of Life
1. What do you know about evolution?
2. What is evolution?
3. What is paleontology?
4. What was Lamarck’s view?
5. What was Darwin’s view?
6. Summarizing Darwin’s view
- Natural selection is differential reproductive success
- Natural selection occurs through interactions between
the environment and the variability among individual
organisms in a population
- The product of natural selection is the adaptation of a
population of organisms to their environment
7. What is artificial selection?
- Selective breeding to encourage the occurrence of
desirable traits
Figure 22.10 Artificial selection
Terminal
bud
Lateral
buds
Brussels sprouts
Cabbage
Flower
cluster
Leaves
Cauliflower
Kale
Stem
Flower
and
stems
Broccoli
Wild mustard
Kohlrabi
Chapter 22: Descent with Modification: A Darwinian
View of Life
1. What do you know about evolution?
2. What is evolution?
3. What is paleontology?
4. What was Lamarck’s view?
5. What was Darwin’s view?
6. Summarizing Darwin’s view
7. What is artificial selection?
8. What is the evidence for evolution?
- Homologous structures – similar structures with
different functions show signs of evolution from a
common ancestor, may be vestigial organs
Figure 22.14 Mammalian forelimbs: Homologous structures
Human
Cat
Whale
Bat
Chapter 22: Descent with Modification: A Darwinian
View of Life
1. What do you know about evolution?
2. What is evolution?
3. What is paleontology?
4. What was Lamarck’s view?
5. What was Darwin’s view?
6. Summarizing Darwin’s view
7. What is artificial selection?
8. What is the evidence for evolution?
- Homologous structures – similar structures with
different functions show signs of evolution from a
common ancestor, may be vestigial organs
- Comparative embryology
- Pharyngeal gill slits
- Post-anal tail
Figure 22.15 Anatomical similarities in vertebrate embryos
Pharyngeal
pouches
Post-anal
tail
Chick embryo
Human embryo
Chapter 22: Descent with Modification: A Darwinian
View of Life
1. What do you know about evolution?
2. What is evolution?
3. What is paleontology?
4. What was Lamarck’s view?
5. What was Darwin’s view?
6. Summarizing Darwin’s view
7. What is artificial selection?
8. What is the evidence for evolution?
- Homologous structures – similar structures with
different functions show signs of evolution from a
common ancestor, may be vestigial organs
- Comparative embryology
- Pharyngeal gill slits
- Post-anal tail
- Molecular biology
Figure 22.16 Comparison of a protein found in diverse vertebrates
Species
Percent of Amino Acids That Are
Identical to the Amino Acids in a
Human Hemoglobin Polypeptide
100%
Human
Rhesus monkey
95%
Mouse
87%
Chicken
69%
Frog
Lamprey
54%
14%
Chapter 22: Descent with Modification: A Darwinian
View of Life
1. What do you know about evolution?
2. What is evolution?
3. What is paleontology?
4. What was Lamarck’s view?
5. What was Darwin’s view?
6. Summarizing Darwin’s view
7. What is artificial selection?
8. What is the evidence for evolution?
- Homologous structures – similar structures with
different functions show signs of evolution from a
common ancestor, may be vestigial organs
- Comparative embryology
- Pharyngeal gill slits
- Post-anal tail
- Molecular biology
- Biogeography – geographical distribution of species
Fig. 22.17 Different geographic regions, different mammalian “brands”
NORTH
AMERICA
Sugar
glider
AUSTRALIA
Flying
squirrel
Chapter 22: Descent with Modification: A Darwinian
View of Life
1. What do you know about evolution?
2. What is evolution?
3. What is paleontology?
4. What was Lamarck’s view?
5. What was Darwin’s view?
6. Summarizing Darwin’s view
7. What is artificial selection?
8. What is the evidence for evolution?
- Homologous structures
- Comparative embryology
- Molecular biology
- Biogeography – geographical distribution of species
- Fossils
Figure 22.18 A transitional fossil linking past and present