Download The Theory of Evolution

The Theory of Evolution
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I. The theory of Evolution by
Natural Selection
A. Darwin Proposed a Mechanism
for evolution
1. The theory of evolution has
developed through decades of
scientific observations and
experimentation.
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C. Darwin developed his idea
(don’t have to write all this, just
listen)
1. Darwin had a hard time in
school.
2. His father was a wealthy doctor and
wanted him to become a doctor or a
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3. Darwin ditched classes and spent
most of his time outdoors.
4. At 16 Darwin was sent away to
study medicine.
5. Darwin skipped lectures to collect
specimens.
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7. Darwin did get a degree in
theology but he liked science
better.
8. Darwin was bored so at 22 he set on
the HMS Beagle a boat that would
change his life forever.
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D. Science before Darwin’s voyage
1. Before Darwin most scientists and
non-scientists thought that each species
was a divine creature, unchanging and
existing as it originally created.
2. In 1809 the scientist Jean Baptist
Lamarck proposed how evolution occurs.
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3. He thought that things evolved
with the use/disuse theory.
4. According to Lamark that these
traits were then passed on to the
offspring.
5. We now know this is WRONG
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E. What Darwin saw during his
voyage
1. He saw different animals with
different characteristics on the
Galapagos Islands.
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F. Darwin sought a Reasonable
Explanation for Evolution
1. When Darwin returned his voyage
at age 27, he continued his lifelong
study of plants, animals and geology.
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2. Thomas Malthus
helped Darwin out
when he wrote the
human populations
are able to increase
faster than the food
supply.
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3. Examples: Tree seeds- Lots but
not all of them will develop into a
tree.
4. A population consists of all the
individuals of a species that live
together in one place at one time.
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5. Darwin realized that Malthus’s idea
about the human population apply to all
species.
6. Individuals that have physical or
behavioral traits that better suit their
environment are more likely to survive and
reproduce than those that do not have such
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traits.
7. Darwin called this process natural
selection.
8. Darwin suggested that organisms
differ from place to place because their
habitats present different challenges.
9. The changing of species that results in its
better-suited environment is called
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adaptation.
10. Darwin also noticed that
organisms more closely resemble
those living in nearby.
11. Darwin published his ideas in
1859. His book was called, “On the
Origin of Species by Means of Natural
Selection.”
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http://carrot.mcb.uconn.edu/~olgazh/photogal/galapagos/santa_cruz/
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G. Darwin’s Ideas have been
updated
1. Natural selection causes
change WITHIN populations.
2. We now know that genes are
responsible for inherited traits.
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3. Natural selection causes the
frequency of certain alleles in a
population.
4. The environment differs from place
to place.
5. Isolation is the condition in which
two populations of the same species
cannot breed with one another.
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6. As the two isolate populations of
the same species become more
different over time, they may
eventually be unable to breed with
one another.
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7. Over long periods of time,
events such as climate changes
and natural disasters result in some
species becoming extinct.
8. Which means they disappear
permanently.
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II. Evidence of Evolution
A. Fossils Provide an objective
record of evolution
1. Most scientists agree on the
following three things:
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a. Earth is about 4.5 billion years
old.
b. Organisms have inhabitant
Earth for most of its history.
c. All organisms living today
evolved from earlier, simpler life
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2. Paleontologists study fossils to
compare the past verse the
present.
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B. Biological Molecules contain a record of
evolution
1. If species have changed over time, then
the genes that determine their characteristics
should also have changed.
2. As species evolved, one change after
another should have become part of their
genetic instructions through mutations.
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3. Therefore a species proteins
and nucleic acids would show these
changes.
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C. Anatomy and Development
suggest common ancestry
1. Comparisons of the anatomy
(structures) of different types of
organisms often reveal basic
similarities in body structures, even
though their functions may be very
different.
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2. Sometimes bones are present in
an organism but are reduced in size
and either have no use or have a
less important function . These
structures are called vestigial
structures.
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3. Homologous structures are
structures that share common
ancestry. Same structure different
function.
4. Example: A whale flipper and a
human have the same structure but
different function.
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5. Analogous structures are
structures that DO NOT share
common ancestry. They have the
same function but different
structure.
6. Example: A bird wing and a
butterfly wing both fly but they
have different bones.
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7. The
evolutionary
history of
organisms is also
seen in the
development of
embryos
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D. Does evolution occur in spurts?
1. There are two theories of how
evolution occurs.
2. Gradual change over a long
period of time leads to species
formation called gradualism.
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3. Rapid change in species is
separated by periods of little or no
change is called punctuated
equilibrium.
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III. Examples of evolution
A. Natural Selection changes the
makeup of population
1. Cause and effect. Everything
that has a cause in nature will have
an affect.
2. Example- kettlewell and his
moths.
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B. Overview of natural selection
1. All species have genetic
variation
2. The environment presents
many different challenges to an
individual’s ability to reproduce.
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3. Organisms tend to produce more
offspring than their environment can
support, thus the animal must survive
to live.
4. Individuals that are able to cope
with the challenges of their offspring
tend to leave more offspring than those
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less suited.
5. The traits of the individuals best
suited to a particular environment
tend to increase in a population
over time.
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C. Industrial
melanism
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D. Beaks of finches
1. Beaks of finches evolved to
what the finch is eating.
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E. The formation of New Species
Begins with Small Changes
1. Species formation occurs in a
series of stages.
2. The accumulation of differences
between gropes is called divergent.
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3. Within populations, divergence leads
to the formation of new species. This is
called speciation.
4. Over time, populations of the same
species that differ genetically because
of adaptations to different living
conditions become what biologists call
ecological races.
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F. Maintaining new species
1. What keeps new species
separate? Why are even closely
related species usually unable to
interbreed?
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2. See page 293 on frog mating
months.
3. Reproductive isolation is the inability
of formerly interbreeding groups to
mate or produce fertile offspring.
4. Species formation is continuously
being documented.
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THE END
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