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Transcript
History of the Earth
How old is the earth?
• The earth is approximately 4.6 Billion
years old
• Scientists believe that life originated
in the oceans between 3.9 & 3.4
billion years ago.
• How do we know that?
• Paleontologists
– are scientists who study ancient life
• They study Fossils- Evidence of an
organism that lived long ago
Evidence of Evolution
A.
Evidence from Fossils
1. Types: Imprints, molds (impressions),
casts (filled impression), tracks, hard
parts, actual remains.
2. Dating Fossils
a) Absolute Dating1) Radioactive isotopes- C-14 dating
b) Relative Dating
1) Sediments are layed down in
strata
2) Lowest layers are oldest
3) A fossil's position in
undisturbed rock gives its age
relative to other fossils.
The Fossil Record
a) Creates the Geologic
Time Scale
b) Oldest fossils found are
3.5 billion years old and
are prokaryotic cells
(bacteria).
c) Fossils show earth's
changes (Organisms,
Climate, Environment)
Biogeography- geographical distribution of species.
• What frame of time do we put the
earth in?
• Divided into 4 major Eras
–1. Precambrian
–2. Paleozoic
–3. Mesozoic
–4. Cenozoic
Precambrian Era
• Accounts for 87% of the Earth’s History.
• There were photosyntheic organism, and
eukaryotic organisms.
• By the end there were multicellular
eukaryotes such as sponges and jelly
fishes.
Paleozoic Era
• Lasted until 248 million years ago.
• Fishes appeared in the waters, and there
is evidence of ferns and early seeded
plants.
• By the end about 90% of marine species
and 70% of the land species disappeared.
Mesozoic Era
• About 248 Million years ago
• Divided into 3 periods:
– Triassic Period- 1st dinosaurs
– Jurassic Period- 1st birds
– Cretaceous Period- 1st flowering plants
Mass Extinction
• The mass extinction of the dinosaurs
marked the end of the Cretaceous Period
about 65 million years ago.
• Not only dinosaurs, but more than 2/3rd of
all living species became extinct.
Mass Extinction
• Some scientists propose that a large meteorite
collision caused the extinction.
• The collision would have filled the atmosphere
with thick toxic dust that changed the climate to
one in which many species could no longer
survive.
• There is evidence of a large crater in the waters
off eastern Mexico.
Cenozoic Era
• Began about 65 million years ago.
• This is the Era we live in today!
• The modern human species appeared
perhaps as recently as 200,000 years ago.
Make a time line of earth’s history:
1. Turn to page 374-375
2. Using a meter stick construct a time line
of earth’s history
3. 1 meter = 1 billion years
4. 1 centimeter = 10 million years
5. 1 millimeter = 1 million years
6. Follow the instructions and construct
your timeline
UNIT XII – EVOLUTION
Test Friday 3-4
THE THEORY OF EVOLUTION
(pp. 369-386)
The theory of evolution is one of the most
fundamental concepts in Biology. Evolution
Is defined as _________
in a
changes
__________________over
time. The
population of organisms
scientist considered to be the founder of
modern evolutionary theory is
______________.
Charles Darwin
A. History of Evolutionary
Theory
During the 1700s, several scientists
began challenging the idea of a
world in which changes did not
occur. These scientists and their
hypotheses were very important to
Darwin’s work.
A. History of Evolutionary
Theory
Geologists (Hutton & Lyell) first
1. Gradualism - __________________
older
suggested that the planet was much ______
than previously thought; began to find
changes were slowly, but
evidence that _______
constantly taking place.
A. History of Evolutionary
Theory
2. Malthus – Published an essay that had a
huge impact on Darwin. Proposed that
organisms over
____ - reproduce; in other words,
reproduce at a _____
greater rate than resources
can supply
A. History of Evolutionary
Theory
3. Lamarck
Lamarck was one of the first scientists to propose
changes in
a mechanism for evolution; that is, the _______
population
time
a _________
of organisms over _____.
His major
hypotheses included:
3. Lamarck
Cont.
Tendency Toward Perfection – Stated that
organisms were continually changing in
more successfully
order to live
________________.
3. Lamarck
Cont.
size
Use and Disuse – Changes in ____
and/or ______
shape of a structure in an
organism was a response to use or disuse.
grew bigger
Structures used extensively ________
and structures used less frequently
got smaller
__________.
Acquired Traits
Inheritance of ________
Acquired Traits
B. Charles Darwin
(1809 – 1882)
1. Darwin’s History
Darwin’s data was collected on a 5-year
journey around the world on the USS
Beagle
______. He made observations and
collected data throughout the journey.
He used this data to propose a
hypothesis
________ to explain the diversity he saw.
1. Darwin’s History
Cont.
The area that had the greatest impact on
Galapagos Islands due
Darwin was the _________
to the differences he saw in the same
animals living on different islands.
Galapagos
2. Darwin’s Observations
• Members of a population often vary greatly in
traits
their _____.
parents to offspring
• Traits are inherited from __________________.
more
• All species are capable of producing _____
offspring than environment
_____________________
can support
food or other resources,
• Due to a lack of ______
many of the offspring will
_______________.
not survive
3. Darwin’s Theories
Based on his observations and the
hypotheses of other scientists:
• Organisms with favorable ____
traits tend to
reproduce thereby leaving
survive and _________;
more descendents than other individuals
• This will result in an accumulation of these
offspring changing the
traits in the ________,
genetic
original _______make-up
of the population
4. Darwin’s Legacy
• Did not publish his findings for years
• Alfred Wallace – formed identical
hypotheses
___________
based on his research.
Sent his manuscript to Darwin, and finally
Darwin was persuaded to publish his own
conclusions
Origin of Species
• Released “______________”,
still
considered one of the greatest scientific
studies ever
III. THE PRINCIPLES OF
EVOLUTIONARY THEORY
A. Evolution occurs because of natural
selection - a mechanism for change that
occurs when organisms with favorable
_________
characteristics for a particular environment
______, reproduce
________, and pass these
survive
offspring
characteristics on to ________.
III. THE PRINCIPLES OF
EVOLUTIONARY THEORY
B. The ability of an organism to survive
and reproduce in its environment is
fitness
known as ________________.
III. THE PRINCIPLES OF
EVOLUTIONARY THEORY
C. Fitness is based on _____________.
adaptations
An adaptation is any trait that aids in the
survival
reproduction of an organism.
_______ and ___________
on a cactus,
Examples of adaptations are thorns
____________
___________________________________
camouflage
, antibiotic resistance in bacteria
III. THE PRINCIPLES OF
EVOLUTIONARY THEORY
D. As organisms ________
survive and adapt,
speciation may occur. Speciation is
_________
the formation of new species - a group of
breed
similar organisms that _______
with one
fertile offspring….
another and produce ___________
that
is, babies that can make babies
___________________________.
III. THE PRINCIPLES OF
EVOLUTIONARY THEORY
E. The failure of an
adapt
organism to _____
to changes in its
environment will
ultimately lead to its
_________
extinction
because of
natural selection
_______________.
IV. EVIDENCE FOR EVOLUTION
A. Fossils – Fossils are
preserved bones and traces of organisms
______________________________________
Fossils provide a record of earlier life and evidence
that evolution has occurred.
B. Biogeography – Variations are seen in the
environment
same types of animals based on their__________.
In addition, there are some organisms that live in
very different locations but they have similar
characteristics because ____________________
their environment are similar;
for
example, climate, food, etc.
______________________.
Copyright Pearson Prentice Hall
IV. EVIDENCE FOR EVOLUTION
C. Homologous Structures – Scientists use
anatomical studies of different organisms for
evidence of evolutionary relationships. For
example, appendages that are very similar in
structure, but differ in function are known as
homologous structures. Examples of
____________
homologous structures are
arm of human, flipper of dolphin,wing of bat
_____________________________________.
IV. EVIDENCE FOR EVOLUTION
D. Vestigial Structures - A structure that is
reduced in function in a living organism, but may
have been used by an ancestor is known as a
vestigial structure. A structure may become
_______
vestigial when an organism changes in form or
behavior. Examples are wings
______________
of ostrich
eyes
on cave fish, human appendix
_______________________________.
IV. EVIDENCE FOR EVOLUTION
E. Embryology – Similarities in the
structures of developing ________
embryo of
different organisms are considered to
be proof of a close evolutionary
relationship.
IV. EVIDENCE FOR EVOLUTION
F. DNA Sequencing – Scientists use
DNA studies to determine the
evolutionary relationship between
organisms. The more similar the DNA,
the
closer the evolutionary relationship
_______________________________
V. MECHANSIMS FOR
EVOLUTION
Evolution does not occur in an
individual; instead it refers to
heritable
changes that occur in a
________________
__________ over time. There must be
population
genetic
mechanisms available for ________
changes to occur:
V. MECHANSIMS FOR
EVOLUTION Cont.
A. Mutation – A mutation is a
change
in DNA
______________.
Although mutations
harmful sometimes
are most often _______,
the resulting change in _________
phenotype may
be beneficial to an organism under
certain conditions.
In jaguars, the mutation is dominant hence
black jaguars can produce both black and
spotted cubs, but spotted jaguars only produce
spotted cubs when bred together.
V. MECHANSIMS FOR
EVOLUTION Cont.
gametes
If the change occurs in the ________,
this change will be passed onto the
offspring of that organism. A positive
mutation that provides a survival
advantage is known as an _________.
adaptation
V. MECHANSIMS FOR
EVOLUTION Cont.
B. Diploidy – Most organisms are
diploid, which
means _______________________.
double set of chromosomes
This allows
for increased genetic variation in a
population.
Heterozygote Advantage – Seen in
malaria
sickle cell allele and _________.
_______________
Recombination – Leads to increased
genetic variation as a result of
_____________
crossing over during __________
prophase I
of _______.
meiosis
V. MECHANSIMS FOR
EVOLUTION Cont.
C. Gene Flow – Gene flow occurs when
organisms from one community migrate to
alleles
another. This introduces new _________
population which can lead to a
into the _________
change in the genetic make-up of the
population.
V. MECHANSIMS FOR
EVOLUTION Cont.
D. Genetic Drift – This describes a
situation in which change in a
population is magnified because the
population size is very ______.
small
Causes of genetic drift include
V. MECHANSIMS FOR
EVOLUTION Cont.
Bottleneck effect – large portion of
population ______________________
destroyed in disaster
Founder effect – segment of
population moves to new ________
habitat
Simple
illustration
of founder
effect. The
original
population
is on the
left with
three
possible
founder
populations
on the right