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1/2/2017
1
Descent With Modification:A Darwinian View of Life
Chapter 22
Objectives for Chapter: 22
1. Understand the following contributions made by the following as they relate to Darwin’s Theory of evolution.
Aristotle, Plato
Linnaeus
Cuvier
Hutton, Lyell
Lamarck, and Malthus
Alfred Wallace
2. Know the main observations and related inferences that Darwin suggested to explain natural selection as a mechanism for evolutionary change.
3. Know the main steps that make up Darwin’s theory of evolution.
4. Know the main aspects of Darwin’s voyage that influenced his theory: including South American flora and fauna, Galapagos Islands, Finches, tortoises
What is Evolution?
A change in the gene pool of a population in
response to various stimuli exhibited by a
species over time.
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Geologist Theories
Hutton – 1795
Gradualism
Cuvier – 1815
Catastrophism
Lyell – 1830
Uniformitarianism
Catastrophism
Naturalist’s Theories
Carolus Linneaus
1707-1778
Thomas Malthus – 1798
Principles of populations
Alfred Wallace – 1858
Theory of Natural Selection
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Jean Baptist Larmark
Theory of Inheritance of Acquired
Characteristics - 1801
Change is made by what
the organisms wants or need
and then is passed down
to offspring.
WRONG !!!
Why?????
Charles Darwin
1809-1882
English Naturalist
At age 22 set sail on H.M.S. Beagle
for South America – Galapagos
Islands.
Wrote The Origin of Species
Three major findings: Fossils,
Geographical Patterns and
Similarities among the Oceanic
Islands.
The Voyage that Changed Everything
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What leads to the change of
organisms?
Artificial Selection
Man selects the desired traits
Dogs
Horses
Pigeons
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What leads to the change of
organisms?
1. Over reproduction
Many organisms produce
more than the environment
can accommodate.
Carrying Capacity – the #
of individuals a given area
will hold.
What leads to the change of
organisms?
2. Variation among species.
Some due to genetic changes called mutations.
Most due to genetic diversity!
What leads to the change of
organisms?
3. Limited resources
Food
Shelter
Territory
Mates
Water
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What leads to the change of
organisms?
4. Competition
Fast
Strong
Smart
Hide
Bluff
Make noise
What leads to the change of
organisms?
5. Reproductive
Success
Able to make
offspring and pass
their genes on to the
next generation.
The Origin of the Species convinced most
biologists that species are the products of
evolution.
What was missing in Darwin’s explanation was an
understanding of inheritance that could explain
how chance variations arise in a population while
also accounting for the precise transmission of
these variations from parents to offspring.
Although Gregor Mendel and Charles Darwin were
contemporaries, Mendel’s discoveries were
unappreciated at the time, even though his principles of
heredity would have given credibility to natural
selection
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•The finches of the Galapagos Islands diversified after an initial colonization from the mainland to exploit different food sources on different islands.
Theory of Natural Selection
Those individuals that possess superior physical, behavioral, or other attributes are more likely to survive than those that are not so well endowed.
“Survival of the Fittest”
Those best able to reproduce!
Biodiversity
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Pocket Mice
Biological diversity is something to relish and
preserve, but it can also be a bit overwhelming.
Evidence of Evolution
Fossil Record
Earliest 3.5
Billion yrs. Old
Cell type?
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Comparative Anatomy
Homologous Structures
Same origin, close to same structure with a different function.
Examples
Comparative Anatomy
Analogous
Structures
Same function
different structure.
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Comparative Anatomy
Vestigial Organs
Structures that serve no purpose
Often homologous with other organs useful in other species
Examples- eye on cave fish
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Molecular Biology
*Sequencing of lettering
of DNA
*Biochemical
Cytochrome C
Blood Proteins
Amino Acids
Development
Embryological
Development
Gene Expression
Most embryos develop
almost identically