Transcript Notes: Evolutionary Theory

Evolution
1. Evolution = change in population over time
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A. Results in:
1. new types of organisms
2. extinction of other organisms: 99% of all
types of organisms that ever lived are now
extinct.
B. Fact or Theory
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1. It is scientific fact that evolution has occurred
through the history of life.
2. Theory of evolution explains how evolution takes
place including mechanisms and processes.
II. Formation of Evolutionary Theory
A. Jean Baptiste Lamark
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1. Hypothesis (1809):
a. A change in the environment causes changes
in the needs of organisms living in that
environment, which in turn causes changes in
their behavior.
b. Altered behavior leads to greater or lesser use
of a given structure or organ; use would cause
the structure to increase in size over several
generations, whereas disuse would cause it to
shrink or even disappear. This rule Lamarck
called the "First Law" in his book Philosophie
zoologique.
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c. Lamarck's "Second Law" stated that all
such changes were heritable.
2. Flaw: Body building or Violin Virtuoso Issue:
3. Disproved by August Weismann with mouse tail
experiment. He docked the tails of mice over 22
generations without cutting any tails of new born
mice.
B. Darwin’s Theory = Natural Selection = living things
that are best suited to their environment will
survive.
 1. Darwin’s Voyage: Aboard the HMS Beagle as a
naturalist. Sailed the world collecting data.
Spent much time on the Galapagos Islands.
Made maps, did geological studies, and studied
plants and animals of different regions.
2. Darwin’s Influences:
 a. Charles Lyell – geologist that reasoned that
geological forces are very slow uniform
processes therefore the earth must be very old.
 b. Thomas Malthus – economist stated when
populations exceeds its resources disasters will
limit the growth of the population.
3. The Origin of Species = wrote 20 years after
his voyage. Explained his theory.
 a. There is variation within pollutions.
 b. Some variations are favorable
 c. More young are produced in each generation
than can survive.
 d. Those that can survive and reproduce are those
with favorable variations.
 e. Over enormous spans of time, small changes
accumulate, and populations change.
C. Stephen Jay Gould – punctuated equilibrium
 1. Interpret the gaps in the fossil record as
representing times when the evolutions of
species take place.
 2. Long periods of stability in species population
and then a brief period of rapid genetic change.
III. Changes in Living Things
A. Adaptations = a trait that makes an organism
better able to survive in an environment.
B. Mutations = A change in the DNA/genetic code
 1. Source of new traits that help organisms survive
 2. Natural events may be helpful, harmful, or have
no effect at all.
 3. Mutations are the reason for variation
IV. Evidence for Evolution
A. Fossil Record
 1. Imprint of a leaf, footprint, organism trapped in
ice or sap, skeleton
 2. Usually formed in sedimentary rock layers.
 3. Younger layers are those found on top of deeper
older layers
 4. The number of fossil species still alive decreases
as the rock age increases.
B. Comparative Anatomy: Similarities in the
anatomy or structure of organisms used to
help determine their ancestry.
 1. Homologous structures: Characteristics that are
similar because they were inherited from a
common ancestor. Examples: Bones in the
forelimbs of humans, bat, bird, and whale.
 2. Vestigial structures: Inherited but unused
structures. Examples your appendix and tail
bones, hip bones in snakes and certain whales.
 3. Analogous structures: Structures that are similar
in purpose but not inherited from a common
ancestor. Examples: wings in birds and
butterflies.
C. Comparative Embryology: Embryos of related
organisms develop in very similar ways.
Examples: Reptiles, birds and mammals have gill
pouches at a certain stage in embryonic
development.
D. Comparative Biochemistry: Different species of
animals have a similar chemical make up.
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1. Dependence on water
2. all life is based on C, H2, N, O, & P
3. The genetic code is made up of the same
genetic alphabet
4. Similarities between genes.