Transcript Evolutionary Theory

Evolutionary Theory and
Evidence
Evolution Notes Part 1
Evolutionary Theory
• What is
evolution?
• Change over time
• The process by which modern
organisms have descended
from ancient organisms
The theory of Evolution
• Evolution is known as the gradual change
in the characteristics of a species over
time.
• A species is a group of organisms whose
members look alike and successfully
reproduce among themselves.
Early Ideas on Earth’s Animals
• Aristotle believed that species were fixed
creations arranged by their complexity
• This idea lasted 2000 years
Contributor’s to Darwin’s thinking
include:
Hutton – theory of geological change (gradualism)
changes in earth due to slow continuous processes
Thomas Malthus- struggle for existence (resources)
Jean-Baptiste Lamarck – Stated that changes are adaptation to environment acquired
in an organism’s lifetime
Also stated that changes were passed to offspring (Inheritance of Acquired Traits)
Law of use and disuse – organisms could change size or shape of organs by using
them or not using them.
- if a body part were used; it got stronger
- if a body part was not used it deteriorated
Contributor’s to Darwin’s thinking
include:
Jean-Baptiste LamarckTendency toward perfection- organisms are continually
changing and acquiring features that help them live
more successfully in their habitat
Ex: Bird ancestors wanted to fly, so they tried until wings
developed.
Charley Lyell- uniformitarianism
geologic processes still changing earth
Georges Cuvier- Species extinction (catastrophism)
evidence Fossils
species disappear due to a catastrophic event to
earth’s crust
Charles Darwin
• Who was
Charles
Darwin?
• What did he
study?
• British naturalist who traveled
around the world on the H.M.S.
Beagle
• Observed living things, making
observations and collecting
evidence that led to his
proposed hypothesis about
how life changes over time
Charles Darwin
• What was the name of • On the Origin of
the book he wrote
Species established
and what was it
evolution by common
about?
descent as the
dominant scientific
explanation of
diversification in
nature.
Darwin’s Theory
• What are the
main points
of Darwin’s
theory?
1.
2.
3.
4.
5.
Organisms vary from each other and
the variety is inherited
Organisms produce more offspring
than can survive
Since more organisms are produced
than can survive, they compete for
limited resources
Each organism has different
advantages and disadvantages in the
struggle for existence
Species alive today are descended with
modification from ancestral species
Evidence for Evolution
• What
1. Fossils – remains or traces of
evidences are
organisms, some of which no
there for
longer exist.
evolution?
Evidence for Evolution
a. Fossils also provide evidence for
evolution. Fossils are the remains of onceliving things that are preserved in Earth’s
rocks.
Evidence for Evolution
b. Fossils have found that many simpler life
forms exist early in Earth’s history.
c. The oldest fossils found are bacteria that
lived 3.8 billion years ago.
Evidence for Evolution
Molecular
2. Comparative biochemistry –
• What
DNA and proteins that show
evidences are
similar structures are also
there for
evidence of common ancestry
evolution?
Evidence for Evolution
a. All living things contain similar DNA,
RNA, and proteins.
b. By comparing DNA sequences of two
organisms, scientists can determine whether
or not the organisms are closely related.
c. The relationship can then be used to
construct evolutionary pathways.
How many amino
acid sequence
differences
between humans
and:
•Horse?
•Tuna?
•Monkey?
• 1. Why can it be said that proteins behave
like molecular clocks?
• 2. What would account for the one or two
differences among two species DNA?
• 3. If the amino acid sequence is similar,
will the DNA sequence also be similar
Evidence for Evolution
• Other kinds of evidence that support
organic evolution are adaptations.
– Anatomical
– Physiological
– Behavioral
Evidence for Evolution
Anatomical
3. Homologous structures – body parts
• What
that have different mature forms but
evidences are
develop from the same embryonic
there for
tissues – evidence of descent from a
evolution?
common ancestor
Evidence for Evolution
Anatomical
A. Homologous structures
have different function
but the SAME structures.
These similarities
indicates that the
organisms probably had
a common (the SAME)
evolutionary origin.
Evidence for Evolution
Anatomical
B. Analogous structures have body parts
that are similar in function but different in
structure. These indicate that the organisms
had different yet related ancestors.
Evidence for Evolution
Anatomical
• What
4. Similarities in embryology –
evidences are early stages of embryonic
there for
development show similarities
evolution?
that suggest common ancestry
Embryology
a. The study of the development of embryos
is the field of embryology.
b. Studies of certain embryos indicate
evolution from a common ancestor.
Evidence for Evolution
Anatomical
• What
5. Vestigial structures – traces of
evidences are
homologous organs that are
there for
very small and no longer used
evolution?
by the modern organism
Functionless Structures ??
• Some body structures, such as the human
appendix and the eyes of cave fish, have
reduced forms. We call these vestigial
structures.
• These structures support the theory of
evolution because they show structural
changes over time.
Evidence for Evolution
Anatomical
What
evidences are
there for
evolution?
6. Some adaptations involve changes
in the structure of body parts:
mimicry and camouflage.
a. Mimicry enables an organism to
copy the appearance of another
species.
b. Camouflage is a structural
adaptation that enables an
organism to blend in with its
surroundings.
MIMICRY
CAMOUFLAGE
Evidence of Evolution
Physiological Adaptations
7. Some adaptations are physiological or
changes in an organisms 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. Take a look at
organisms that have been exposed to
antibiotic and pesticides. The organisms
that survive have become selected 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. 