Download Evolution PPT

The Theory of
Evolution
The theory of Evolution

Evolution is known as the gradual change
in the characteristics of a species over
time.
The theory of Evolution

A species is a group of organisms whose
members look alike and successfully
reproduce among themselves.
The Theory of Evolution

Charles Darwin is considered to be the
founder of modern evolutionary theory.
The Theory of Evolution

On the Origin of Species established
evolution by common descent as the
dominant scientific explanation of
diversification in nature.
Natural selection is a mechanism
for changes in populations that
occur when organisms with
favorable adaptations survive,
reproduce, and pass on traits to the
next generation.
Evidence for Evolution
All living things contain similar DNA, RNA,
and proteins.
 By comparing DNA sequences of two
organisms, scientists can determine
whether or not the organisms are closely
related.
 The relationship can then be used to
construct evolutionary pathways.

Evidence for Evolution

Fossils also provide evidence for
evolution. Fossils are the remains of
once-living things that are preserved in
Earth’s rocks.
Evidence for Evolution
Fossils have found that many simpler life
forms exist early in Earth’s history.
 The oldest fossils found are bacteria that
lived 3.8 billion years ago.

Evidence for Evolution

A paleontologist is someone who studies
fossil evidence
Which layer is Oldest?
Evidence for Evolution

Other kinds of evidence that support
organic evolution are adaptations. These
adaptations can be either:
Anatomical
 Physiological

Anatomical

Homologous structures
have different function
but the SAME structures.
These similarities
indicates that the
organisms probably had
a common ancestor
Anatomical

Analogous structures have body parts
that are similar in function but different in
structure. These indicate that the
organisms had different ancestors.
Anatomical

Some adaptations involve changes in the
structure of body parts: mimicry and
camouflage.

Mimicry enables an organism to copy the
appearance of another species.
MIMICRY
Anatomical

Some adaptations involve changes in the
structure of body parts: mimicry and
camouflage.

Camouflage is a structural adaptation that
enables an organism to blend in with its
surroundings.
CAMOUFLAGE
Vestigial Structures
Some body structures, such as the human
appendix and the eyes of cave fish, have
no function.
 These structures support the theory of
evolution because they show structural
changes over time.

Take a Look!!
Embryology
The study of the development of embryos
is the field of embryology.
 Studies of certain embryos indicate
evolution from a common ancestor.

Physiological Adaptations

Some adaptations are physiological or
changes in an organism’s metabolic
processes.

Keep in mind that all things are made up of
cells and the organelles are structurally and
functionally similar in most organisms.
Physiological Adaptations

Organisms are constantly changing to
adapt to their environment. Organisms
that have been exposed to antibiotics and
pesticides have become “selected” to
survive because they are physiologically
more resistant.
Imagine that there are 10
bacteria growing on your
hand.
You use Germ-x to clean your
hand everyday.
After 4 days, there are still 3
bacteria on your hands that have
survived.
Is there anything special about
these bacteria?
Yes..they have something about
their DNA that has made them
different and strong enough to
survive.
So now what will happen?
Those 3 that are “resistant” will
undergo Mitosis.
And after a week, your hands will be
covered with tons of bacteria that
are ALL resistant to Germ-X. 