Title: Evolution
1Evolution
A. What is Evolution?
1. Several definitions
video 1
video 2
a. descent with modification (Darwin)
b. change in gene frequencies within a population
c. All the changes that have transformed life on
earth from its earliest beginnings to the immense
diversity existing today
2Evolution
A. Historical Development
1. Jean Baptiste Lamarck
a. French biologist proposed a theory of
evolution in 1801
b. Lamarcks Theory
i. Organisms strive to improve themselves need
ii. Most used structures develop and less used
structures are lost use and disuse
iii. Offspring inherited the acquired
characteristics of parents
History
3Evolution
A. Historical Development
1. Jean Baptiste Lamarck
2. August Weismann
a. Disproved Lamarck ideas by chopping of the
tails of mice
b. What?
History
4Evolution
A. Historical Development
1. Charles Darwin
a. Study theology at Cambridge
b. 1831 appointed naturalist aboard the ship HMS
Beagle
i. mission was to create maps for the British Navy
c. Darwin took surveys and collected samples of
plants, animals, rocks, and fossils
History
5Evolution
A. Historical Development
1. Charles Darwin
d. Most famous observations Galapagos Islands
where he spent 2 months
e. Eventually sailed around the world 1831-1835
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video 2
History
6Evolution
A. Historical Development
1. Charles Darwin
f. Wrote a 200 page thesis in 1844 outlining his
theory but he did not publish
WHY?
g. Alfred Wallace came to similar conclusions as
Darwin in 1858 from observations collected in
another area of the world
h. Darwin agreed to a joint presentation with
Wallace to the same scientific body.
History
7Evolution
A. 5 ideas of Darwins Theory
1. Overpopulation
a. Organisms produce more young than will survive
b. example
Fly eggs 250 eggs by one female in one laying
Baby sea turtles
Praying Mantis young from one cocoon
8Evolution
A. 5 ideas of Darwins Theory
1. Overpopulation
2. Variation
a. There exists in a population a large amount of
variation
9Evolution
A. 5 ideas of Darwins Theory
1. Overpopulation
2. Variation
3. Struggle for existence
a. What do organisms struggle for?
i. Lion attack
b. Carrying Capacity how many individuals can
the environment support
i. example deer in CVNP
4. Survival of the
strongest
fittest
a. Those that survive are the best adapted
10Evolution
A. 5 ideas of Darwins Theory
b. Individuals that survive reproduce and pass on
favorable traits
c. Fittest those that reproduce most successful
i. Differential reproductive success
5. Natural Selection
a. Environmental pressures select for the best
adapted
b. Animated example DDT and flies
11Evolution
B. People who helped Darwin
1. Thomas Malthus
a. minister, economist
b. Wrote Essay on Populations
c. Predicted that population would grow faster
than food supply
d. Lead to Darwins idea of struggle for existence
12Evolution
B. People who helped Darwin
1. Charles Lyell
a. geologist
b. Wrote Principles of Geology
c. Proposed the idea of Uniformitarianism
i. Geological processes are constant through time
ii. Challenged the prevailing thought that the
earth was young
iii. Darwin needed large periods of time for
natural selection to work
iv. Uniformitarinism provided Darwin the time
element needed for his theory
13Evolution
B. People who helped Darwin
1. Charles Lyell/
Uniformitarianism
14Evolution
Natural Selection
How Evolution Works
Overpopulation
Genetic Variation
Struggle for Existence
Differential Reproductive Success
Selection occurs based on
- the interaction of the environment and the
existing population variations
- the more severe the environmental pressure, the
more severe the selection process
15Evolution
Natural Selection
- the environment shapes or refines organisms
adaptations
Environmental Pressures
- resources food, water, shelter
- climate cold, hot, wet, dry
- predation how does one survive?
16Evolution
Evidences
A. Anatomical
1. Fossils
a. Remains or traces left in rock strata (layers)
by previous organisms (video becoming a fossil)
b. Preserved in rocks, bogs, tar amber, ice
c. Types of preserved samples imprints,
castings, and amber
17Evolution
Evidences
A. Anatomical
1. Fossils
d. Transitional records
i. Classic example the horse
e. Famous fossils
18Evolution
Evidences
A. Anatomical
1. Fossils
e. Famous fossils