Transcript Theory of Evolution

Theory of Evolution
Charles
Darwin
1831 - Sailed on HMS Beagle
The voyage lasted 5 years
Gathered evidence about
species and how they change
Evidence
South America: Darwin
found fossils of extinct
armadillos that closely
resembled the armadillos
living in the area.
A collection of Glyptodons -- giant armadillo-like
fossils
http://abcnews.go.com/Technology/Science/story?id=6815330&page=2
Evidence
Galapagos Island and coast
of South America had
animals and plants that
were similar to one another
but also different in ways.
Darwin surmised that S.A.
animals migrated and then
changed (over time).
http://abcnews.go.com/Technology/Science/story?id=6815330&page=3
Descent with Modification
Evolution:
Descent with modification
from a common ancestor.
There must be a change in
gene frequency OVER
TIME.
Time is KEY
Evolution???
•
Beetles on a diet
•
Imagine a year or two of drought
in which there are few plants that
these beetles can eat.
•
All the beetles have the same
chances of survival and
reproduction, but because of food
restrictions, the beetles in the
population are a little smaller than
the preceding generation of
beetles.
•
http://evolution.berkeley.edu/evosite/evo101/IIIADescent.shtml
Evolution???
•
Beetles of a different color
•
Most of the beetles in the
population (say 90%) have the
genes for bright green coloration
and a few of them (10%) have a
gene that makes them more
brown.
•
Some number of generations
later, things have changed: brown
beetles are more common than
they used to be and make up
70% of the population.
Population:
All the individuals of a
species that live together in
one place at one time.
Ex: Alligators in the
Everglades
http://www.google.com/imgres?imgurl=http://www.animalwebguide.com/Alligator1.jpg&imgrefurl=http://www.animalwebguide.com/Alligator.htm&usg=__iIeUOzX6AWt62BkR893nxHD9
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Natural
Selection:
Process by which
organisms change in
response to their
environment.
http://jrenseyblog.wordpress.com/2011/07/
Natural Selection cont’d
• Individuals that have physical or
behavioral traits that are better suited
their environment are more likely to
survive and reproduce than those that
do not have such traits.
Adaptation:
The changing of a species
that results in its being
better suited to its
environment.
http://www.johnehrenfeld.com/2009/05/be-careful-with-adaptation.html
List some examples of adaptations
•
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•
•
On the Origin of Species
• Darwin did not
publish his ideas on
evolution until 1859.
• He published On
the Origin of
Species by Means
of Natural Selection
Darwin’s ideas have been updated
• Genes are responsible
for inherited traits.
Darwin’s ideas have been updated
• Isolation leads to species
formation.
• Isolation: the condition in
which two populations of
the same species cannot
breed with one another.
• Populations of the same
species living in different
locations tend to evolve
differently.
http://williamcalvin.com/bk3/img/kaibab.gif
Kaibab Squirrel
Aberts Squirrel
Species:
Group of organisms that are
genetically similar and can
produce fertile offspring.
Darwin’s ideas have been updated
• Extinction leads to species
replacement.
• Climate changes & natural
disasters lead to extinction.
• Extinct: species
disappears permanently.
• Species that are better
suited to the new conditions
replace the old species.
http://hypebeast.com/image/2008/06/nike-plus-human-race-3.jpg
The Theory of Evolution is Supported by Four
Points
1. Variation exists within
the genes of every
population or species.
Some human
examples:
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The Theory of Evolution is Supported by Four
Points
2. In a particular
environment, some
individuals of a
population or species
better suited to survive
(as a result of variation)
and have more
offspring.
The Theory of Evolution is Supported by Four
Points
3. Over time, the traits that make certain individuals of
a population able to survive and reproduce tend to
spread in that population.
The Theory of Evolution is Supported by Four
Points
4. There is clear proof from fossils and many other
sources that living species evolved from organisms
that are extinct.
http://www2.estrellamountain.edu/faculty/farabee/biobk/BioBookEVOLII.html#Evidence%20for%20Evolution
QUESTIONS?