Download Figure 22.0 Title page from The Origin of Species

Chapter 22 - Descent With Modification
Title page from The Origin of Species
published 1859
Charles Darwin -
wrote – Origin of Species by
Means of Natural Selection
- naturalist
- sailed on the Beagle, survey ship, 22 years old
- collected specimens: plants and animals
- he found fossils different from modern species
- Darwin was influenced by Lyell’s Principles of
Geology and thought that the earth was more
than 6000 years old
* - He observed adaptations of plants and animals
that inhabited many diverse environments
Linnaeus (classification)
Hutton (gradual geologic change)
Lamarck (species can change)
Malthus (population limits)
Cuvier (fossils, extinction)
Lyell (modern geology)
Darwin (evolution, natural selection)
Wallace (evolution, natural selection)
American Revolution
French Revolution
U.S. Civil War
1800
1900
1750
1850
1795 Hutton proposes his theory of gradualism.
1798 Malthus publishes “Essay on the Principle of Population.”
1809 Lamarck publishes his hypothesis of evolution.
1830 Lyell publishes Principles of Geology.
1831–1836 Darwin travels around the world on HMS Beagle.
1837 Darwin begins his notebooks.
1844 Darwin writes essay on descent with modification.
1858 Wallace sends his hypothesis to Darwin.
1859 The Origin of Species is published.
Historical Ideas
Taxonomy - Linnaeus:
naming and classifying the diverse forms of life “for the greater
glory of God”: kingdom, phylum, class, order, family, genus, species
paleontologist, fossils, recognized that extinctions occurred
he argued it must have been due to catastrophism
Paleontology – Cuvier:
Gradualism - Hutton: geologist: profound change in the Earth’s features,
slow and continuous
Uniformitarianism - Lyell :
geologist, geologic processes have not changed throughout
Earth’s history rates of building and eroding same now as in
past
Evolution - Lamark : 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
Populations - Malthus :
studied populations
human suffering was due to populations
Natural Selection - Darwin :
Inheritance - Mendel :
2 ideas: 1. descent with modification
2. natural selection through adaptation
parents pass traits to offspring
Acquired traits are not inherited
The Voyage of HMS Beagle
- discovered that most of the animal species on the Galapagos lived nowhere else
in the world but they resemble species on the South American mainland
- Darwin studied Finches (birds)
adaptation
-In reassessing his observations, Darwin perceived
to the
environment and the origin of new species as closely related processes
(a) Cactus-eater
(c) Seed-eater
(b) Insect-eater
In the Darwinian view,
the history of life is
like a tree with
branches representing
life’s diversity
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
•
Darwin then described four observations of nature and from these drew two
inferences
Observation #1: Members of a population often vary greatly in their traits
Observation #2: Traits are inherited from parents to offspring
Observation #3: All species are capable of producing more offspring than the
environment can support
Observation #4: Owing to lack of food or other resources, many of these offspring
do not survive
•
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
Observation #1: Members of a population often vary greatly in their traits
•
individuals
populations evolve over time
Note that ______________do
not evolve; ______________
•
Natural selection can only increase or decrease heritable traits in a population
•
Adaptations
________________
vary with different environments
•
edits or _________
selects for
Natural selection does not create new traits, but ________
traits already present in the population
•
selected for
The local environment determines which traits will be __________________
or
selected against
_________________ in any specific population
Fig. 22-12b
(b) A stick mantid
in Africa
Fig. 22-12a
Observation #2:
Traits are inherited
from parents to
offspring
(a) A flower mantid
in Malaysia
The Evolution of Drug-Resistant HIV
•
selects for viruses resistant to these
The use of drugs to combat HIV _______________
drugs
•
reverse transcriptase to make a DNA version of
HIV uses the enzyme ________________________
its own RNA genome
•
The drug 3TC is designed to interfere and cause errors in the manufacture of
DNA from the virus
•
variation
Some individual HIV viruses have a ______________
that allows them to
produce DNA without errors
•
greater reproductive success
These viruses have a _______________________________
and increase in
number relative to the susceptible viruses
•
developed resistance to 3TC
The population of HIV viruses has therefore _____________________
•
The ability of bacteria and viruses to evolve rapidly poses a challenge to our
society
Fig. 22-14
The Evolution of Drug-Resistant HIV
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
•
provides evidence of the extinction of species, the origin of
The fossil record __________________
new groups, and changes within groups over time
•
transitions
The Darwinian view of life predicts that evolutionary __________________
should leave signs in the fossil record
•
Paleontologists have discovered fossils of many such transitional forms
A transitional fossil linking past and present
Vestigal structures historical remnants of structures
that had important functions in
ancestors
ex. snakes – pelvis, leg bones
Fig. 22-16ab
The transition to life in the sea
(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)
Homologous structures: anatomical signs of descent with modification
new species descend from
ancestral species
anatomical homologies
Homologous structures - similarity in characteristics resulting from common ancestors
Homologies
– ex. forelimb: human, cat, whale, bat
- anatomical
- embryological – ex. pharyngeal pouches in throat – all vertebrates have
- molecular
– all use same genetic material (DNA)
Analogous structures – body parts resemble one another - evolved independently
ex. fins/body shape: sharks, penguins, porpoise
all are adaptations for
swimming
Fig. 22-18
Pharyngeal
pouches
Post-anal
tail
Chick embryo (LM)
Human embryo
Homologies and “Tree Thinking”
•
evolutionary tree of life can explain
The Darwinian concept of an ___________________
homologies
•
relationships among
Evolutionary trees are hypotheses about the __________________
different groups
•
Evolutionary trees can be made using different types of data, for example,
anatomical and DNA sequence data
_______________________________________________
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
•
independently adapt
Analogous traits arise when groups ____________________________
similar environments
to _______________________
in similar ways
•
ancestry
Convergent evolution does not provide information about _____________
Fig. 22-20
Sugar
glider
NORTH
AMERICA
AUSTRALIA
Flying
squirrel