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Evolution
Ms. Bosinski/ Mrs. Newlove
Evolution
• Evolution-The process by which species
change over time, or become extinct.
• Species-All the organisms that can interbreed
and produce fertile offspring, and look roughly
alike.
• Extinction-When all members of a species have
died and that species no longer exists.
Jean Lamarck
• BEFORE Charles Darwin, Jean Lamark
came up with ideas of how evolution
worked.
• His theories have been proven FALSE.
He believed that organisms could
CHANGE to fit the environment
(Use/Disuse), and that those traits could
be passed on to offspring
Charles Darwin
• Lived in England
• When he was young, he took a voyage on
the H.M.S. Beagle
• They sailed into the Pacific Ocean, to the
Galapagos, and Darwin discovered several
new species, including species of finches
that were found no where else.
• This led him to think about why the finches
on the Galapagos would be different than
those in England.
Darwin
• Basically, Darwin said that living
populations change over time because of
changes in their environment.
• Certain individuals are ‘selected’ to breed
because they are better adapted to the
change in the environment.
• He called this process, ‘natural selection’
Evolution- Some terms
• Adaptation-A trait that an organism has
which helps it to survive its environment.
• Natural Selection-The natural change in
environment which will determine which
traits are useful and which are not; those
traits will be passed on to succeeding
generations.
Darwin’s Theory Includes:
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Overproduction (Too many offspring)
Competition (Struggle for resources)
Variations (Not all members are the same)
Adaptations (Some have favorable
characteristics)
• Natural Selection (The best suited will
survive/ Survival of the Fittest)
• Speciation (Eventually a new species
could form)
THE IMPORTANCE OF
VARIETY…..
• If the environment changes, it is likely that
SOME organisms of a species will survive
if there is more VARIETY!!
• The more DIVERSITY there is in a
population the more stable that population
is.
MUTATIONS
• The source of variations can be traced
back to MUTATIONS, which change the
genetic information (DNA, Genes, or
Chromosomes)
• MOST mutations are HARMFUL, but
some can be helpful, as in the dark
peppered moth!
Peppered Moth
• The peppered moth comes
in two colors: white and
black
• The white color is favored
by natural selection,
because the bark of the
trees that the moth rests on
is white. This makes it
hard to be spotted by birds.
Peppered Moth
• However, when the factories in England
started up, the bark of the trees often was
covered in soot. This made the bark of the
trees black. Scientists started seeing the
moth population change from almost all
white to almost all black.
Peppered Moth
• If this had happened long enough, the
moth may become a new species.
Evidence-Observations
• Evidence of Evolution
• Fossils-Fossils can be imprints, casts,
molds, or petrified parts of animals and
plants that lived thousands to millions of
year ago.
• Fossils form in
sedimentary rocks
which form in water
History of Life on Earth
• The pattern seems to be from simpler
forms to more complex forms
• Several mass extinctions of large numbers
of species have caused rapid evolution to
occur, eg. 65 million years ago, and the
Permian Mass Extinction
Evidence-Observation
• Homologous Structures – Have SIMILAR
STRUCTURE, but DIFFERENT functions
Evidence of Evolution
• Comparative Embryology- Some
organisms look VERY similar in the early
stages of development.
Evidence
• DNA!
• Scientists have compared the DNA of
many organisms, and organisms that have
similar structures often have very similar
DNA.
• Humans and Chimpanzees have 98% the
same DNA
How does Evolution Work?
• Genetics!
• Each species has a natural variation,
because of different alleles. When
something in the environment changes,
some traits may provide an advantage,
those traits, and therefore genes, are
passed on to the next generation.
So…
• The genes which code for traits which help
the organism survive are going to be
passed on.
• Those that are not helpful are not going to
be passed on, but eliminated from the
gene pool.
• Over many generations, a new species
can form.
The Rate of Evolution
For some species, the
rate of evolution has
been SLOW, as in the
HORSESHOE CRAB
which has changed
very little over 300
million years.
However, HORSES
have evolved a lot over
60 million years.
Evolution Videos
• Structural Adaptations of Australian
Wildlife
• http://youtu.be/wEDxThDINgQ
• How Evolution Works
• http://youtu.be/xkwRTIKXaxg
• Finches on the Galapagos
• http://youtu.be/l25MBq8T77w
• Natural Selection & Adaptations
• http://youtu.be/kjgNT0rBy_8