Biology 1A Sept 22, 1998
Lecture 7 - Evolution
Page Contents :
Overview of Lecture:
The diversity of life is the result of evolution.
Evolution is descent with modification through time.
Charles Darwin proposed natural selection as the mechanism of evolution.
Evolution since Darwin.
Overview of Lab:
(A bullet indicates a handout.)
- Patterns in Evolution.
I. The diversity of life is the result of evolution.
A. Life has been, and is, very diverse
II. Evolution is descent with modification through time.
1. Reprise: Five Kingdoms
B. This diversity is the result of evolution
a. What are species?
b. How many species are there?
1. Evolution is "change through time".
C. Evidence for evolution
2. Evolution has occurred over a vast span of time
3. Species can change over time
4. Composition of species can change over time.
5. Species can go extinct.
1. Fossils provide evidence of evolution
a. A fossil is any evidence of life preserved in the geologic record.
2. Other lines of evidence
b. Fossil evidence indicates that life has changed over time.
c. Transitional fossils possess a mix of traits from two currently separate groups.
a. embryonic development
b. shared morphological features
c. DNA sequences
d. distributions of organisms on Earth
A. Evolution - some common misconceptions
III. Charles Darwin proposed natural selection as the mechanism of evolution.
1. Darwin never used this word
B. is - constantly happening and still going on
a. wasn't in "Origin of Species"
2. Darwin never referred to "survival of the fittest"
b. meant "progress" in Darwin's time, so he purposely avoided it, since evolution is NOT "progress"
c. Great Chain of Being - idea of levels of perfection; a philosophical and religious idea, NOT a scientific idea.
a. social idea published by Herbert Spenser
b. hotly debated in Darwin's time
c. probably influenced capitalism, imperialism, communism, and totaliarianism, but is NOT a scientific idea.
1. Evolution is not an existential concept, but can be observed.
C. descent - offspring tend to look like parents
2. Is evolution "only a theory"?
a. theory versus hypothesis in science.
3. Even before Darwin, scientists appreciated that change had occurred.
b. Evolution is a theory, repeatedly tested and supported by the evidence.
c. some supporting observations
D. with modification
1. Children aren't exact copies of their parents
E. through time
a. There is natural variation in populations
2. Interaction with the environment removes some of the variation
b. This variation results from mutation
c. Variation is the raw material of evolution
d. Populations evolve, individuals cannot.
a. Example: Peppered moths and industrial melanism
3. The result of modification is adaptation.
b. This is selection
c. Note: Selection acts on phenotypes, NOT genotypes
1. Most evolution happens over spans of time that are hard to comprehend.
2. geologic time
1. Genetically determined characteristics of organisms change with time.
2. This change is directed by natural selection.
A. Charles Darwin, England (1809-1882)
IV. Evolution since Darwin.
1. Studied theology, but loved biology and natural history
B. Observations and ideas that contributed to Darwin's Theory
2. 1831-1836 Voyage of HMS Beagle
3. 1859 "On the Origin of Species"
1. Biological richness of tropical forests
C. Why is Darwin's work so important?
3. Oceanic islands
5. Charles Lyell's "Principles of Geology"
a. Rocks have changed over time.
6. Thomas Malthus -- "prodigality of nature"
b. These changes occur according to observable laws.
7. artificial selection
A. We now know a LOT more than Darwin did; his theory has been expanded accordingly.
B. 1920s-1930s : Modern Synthesis incorporated understanding of genetics into evolutionary theory
C. Scales of evolution
1. microevolution - change at or below the level of a species; results from a change in allele frequency in a population
D. Rates of Evolution
2. macroevolution - evolution above the level of species
1. punctuated equilibrium
3. Both concepts probably valid; rate may change over time
|adaptation|| || ||
||geologic time|| || ||
|Archaeopteryx|| || ||
||gradualism|| || ||
|artificial selection|| || ||
||Great Chain of Being|| || ||
||prodigality of nature|
|biogeography|| || ||
||hypothesis|| || ||
|creationism|| || ||
||industrial melanism|| || ||
|descendant|| || ||
||living fossil|| || ||
|diversity|| || ||
||macroevolution|| || ||
||survival of the fittest|
|evolution|| || ||
||mass extinction|| || ||
|extinction|| || ||
||microevolution|| || ||
|fossil|| || ||
||mutation|| || ||
- What are species? What is the number of species estimated to exist today?
- What is diversity and where does it come from?
- What is evolution?
- What is microevolution? What are some examples of observed microevolution?
- What is macroevolution? What are some examples of macroevolution?
- Can extinct species have living descendants? Do they have to?
- Do species that exist today have to have evolved from other species that exist today?
- What is extinction? How is this different from a mass extinction?
- What is a fossil? Are petrified eggs fossils? preserved trackways? preserved burrows? preserved fungal spores? preserved riverbeds?
- Why is Archaeopteryx such an important disovery?
- Besides fossils, what other lines of evidence support the idea of biological evolution?
- Has evolution ever been observed? Has the theory of evolution been tested? How?
- What is the Great Chain of Being, and why is it not part of evolutionary theory?
- Who published the idea of "survival of the fittest"? Is this concept part of evolutionary theory? Why or why not? Do you think it has influenced evolutionary ideas? How?
- Who published the idea of the "prodigality of nature"? Is this concept part of evolutionary theory? Why or why not? Do you think it has influenced evolutionary ideas? How?
- Who published the idea that the Earth itself has changed over time according to observable laws? Is this concept part of evolutionary theory? Why or why not? Do you think it has influenced evolutionary ideas? How?
- Can an individual evolve to better suit its environment? Why or why not?
- What must exist in a population before evolution can occur?
- What is an adaptation? What is a "preadaptation"?
- Explain what happened to the peppered moths in England at the time of the Industrial Revolution? Is this an example of evolution?
- What is geologic time, and why is it important?
- How did the distribution of living organisms on Earth influence Darwin's concept of evolution?
- Why is Darwin's work so important?
- What additions have been made to evolutionary theory since Darwin published "On the Origin of Species"?
- What is creationism? Is creationism science? Why or why not?
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