Transcript Organisms throughout time

Organisms throughout
time
Adaptation, heredity, natural
selection and evolution
Adaptation
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An adaptation is an inherited or set
of traits that makes an organism
better suited to its environment.
Adaptations occur over long periods of
time.
An organisms body shape and location
of its brain are adaptations.
Body symmetry
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Symmetry gives a clue as to the
evolutionary development and complexity of
the organism.
Higher animals, like humans, have bilateral
symmetry, meaning the right and left halves
of the organism are mirror images of each
other.
Other organisms, such as starfish, have
radial symmetry, meaning they are
symmetric about a central axis.
These organisms are usually not well
adapted for movement.
Plant adaptations
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Plants cannot move so they must grow in
such a way to maximize the amount of light
and water they absorb.
Some may have shallow roots that spread
out a long way or have long roots that get
water from very deep under ground.
The Venus Fly Trap has adapted itself to
eating meat in order to get the nutrients it
needs.
Heredity
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Heredity is the passing of traits from one
offspring to another.
Traits are an aspect of an organism that
can be described or measured, such as eye
color, hair color, etc.
Traits are transmitted from parents to
offspring in DNA.
The inheritance of certain traits is what
helps to determine survival in the
environment.
Eventually only those organisms with the
“better” traits will exist.
Natural selection
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Natural selection is the differences in
survival and reproduction among members
of a population.
“survival of the fittest.”
– Only the organisms best suited to the
environment survive and reproduce.
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Factors are obtaining food, shelter, light,
water.
Organisms constantly compete for these
resources
Factors involved in
natural selection
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Variation among individuals in a
population.
Heredity of variable characteristics, such
as fur color or size
Tendency of population size to increase.
“struggle for survival.”
Difference in inherited characteristics that
are passed from generation to generation.
Evolution
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Natural selection is the main reason for
evolution.
Evolution is the gradual change in an
organisms appearance over time.
Charles Darwin is the scientist that
developed the theory of evolution.
Did his research on the Galapagos Islands.
Wanted to explain differences in organisms
he saw there.
Darwin’s analysis
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There is a lot of variation among species
of an organism. No two organisms are
exactly alike.
Population size tends to increase because
of reproduction.
Population size can’t go unchecked or it
would outgrow food supply and living
space.
Huge increases in population seldom
occur, most populations stay around the
same size for long periods of time.
Homework
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Knowing what you have learned about
natural selection and adaptation, how
and why do you think that giraffes
have such long necks? Explain using
examples.