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UNIT 10 “EVOLUTION”
Section 10.1 Early Ideas About Evolution 280-283
Scientist involved in Theory of Evolution
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Linnaeus: Proposed that species could arise through hybridization. Ex. Grapefruit,
Peppermint, Tangelo, Limequat
Buffon: Stated that many species shared common ancestors and was one of the first to
propose that Earth was older than 6000 years old
Erasmus Darwin: Believed that all living things somewhere had a common ancestor.
Also stated that the more complex organisms originated from less complex organisms
Lamarck: Evolution moves towards perfection and complexity. Also believed that
changes in physical traits could be passed on. Ex: If I lost my hand my child wouldn’t
have a hand, Giraffes (Many of his ideas have been dismissed)
Theories of Geologic Change
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Catastrophism: Major natural catastrophes (floods & volcanoes) caused many of the
changes we see in nature.
These major events shaped landforms and caused mass extinctions
Allowed for organisms to move from different locations to new locations
Gradualism: Idea of James Hutton. Thought that the changes on Earth occurred very
slowly and took a VERY long time. The idea is a Geological idea but can be applied to
Evolution of organism
Uniformitarianism: Idea of Lyell, thought that the processes that shaped Earth are
uniform through time. He combined some of the ideas of Lyell and Hutton. His ideas had
a great influence on Charles Darwin
10.2 Darwin’s Observations 284-285
MAIN IDEA
Darwin observed variation among island
species
SUPPORTING DETAILS
- Variation is the difference in the
physical traits of an individual from
those of other individuals in the same
group
- Can happen in members of same
species or different species
- Seen in Galapagos Island with Finches
and Tortosies
Darwin realized species could adapt to their
environment
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Darwin observed fossil and geological
evidence of an ancient Earth
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Species can adapt to their environment
This allows species to better survive in
their habitat
This can lead to genetic change over
time
Glyptodon fossils in Argentina
Showed evidence that Earth should be
more than 6000 years old
Shells of marine organisms in Andes
Mts. also helped to support Lyell’s
ideas
Section 10.3 Theory of Natural Selection 286-291
Artificial Selection: Process by which humans change a species by breeding for certain traits.
Ex: Race Horses
Heritability: Ability of a trait to be passed from one generation to the next
Struggle for survival: As long as resources are available populations grow. Malthus
What is Natural Selection?
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Individuals with inherited beneficial adaptations produce more offspring on average.
Environment is a selective agent
Advantage is for the present not the past or for the future
Breeds aren’t perfect at the beginning they continue to change as the process occurs
4 Main Principles of Natural Selection
- Variation: This is the basis for natural selection. Heritable differences
- Overproduction: Produces competition for resources
- Adaptation: Variation that allows individuals to survive better against its competitors
- Descent with Modification: Adaption that many individuals have that allows an individual to
thrive. Traits will be passed along as long as environment is the same. Genetic change
Section 10.4 Evidence of Evolution 292-296
Main Idea: Evidence of common ancestry among species comes from many sources
Fossils: Allow us to think about age, location, and the environment was like at a specific time
1700’s geologist looked at fossils in rock layers; the deeper layers had fossils that looked
different.
This showed modification through time.
Geography: Different ecosystems, different plants, climates, and predators allow different
species to thrive.
The geography of a location may allow a different species to thrive.
The connection between geography and living things is called biogeography
Embryology: Study of developing organisms
Helped to show Darwin the idea of common descent b/c embryos of different organism all look
the same
Which image is a human, turtle, fish, and bird
Anatomy:
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Homologous Structures- features that are similar in structure but have different functions
in different organisms. Ex: Human hand and bat wing
Vestigial Structures- Remnants of organs or structures that has a use in early ancestors.
Ex. Appendix of human, wings of an ostrich
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Analogous Structures- Structure that perform a similar function but are not similar in
origin Ex. Wings of a bat and wings of a fly