Download File

Theory of Evolution
Evidence of Evolutionary Change
Vocabulary Words
1. Evolution- change over time; the process by which modern
organisms have descended from ancient organisms.
2. Fossil- preserved remains or traces of ancient organisms.
3. Homologous structures- structures that are similar in
different species of common ancestry.
4. Vestigial structure- structure that is inherited from ancestors
but has lost much or all of its original function
5. Analogous Structures- Body parts that share a common
function but not structure
6. Biogeography- The study of where organisms live now and
where they and their ancestors lived in the past
Where did Darwin get his
ideas?
Darwin made several observations when formulating
his theory of evolution. These observations were
based on the following concepts:
1.
2.
3.
4.
5.
The Fossil Record
Biogeography
Comparative Anatomy
Comparative Embryology
Molecular Biology (Genetic Code)
The Fossil Record
• Fossils are evidence of deceased organism from their
preserved remains retained by the earth
• There are several layers of the earth which fossils are found in
• Law of Superposition:
What about the
fossils changes as
we dig deeper
into the layers of
the earth?
Biogeography
Pangaea was the time when the continents were all connected
as one large land mass
Due to plate tectonics, this united large landmass
progressively separated into several continents
The separation of the landmass also separated populations of
organisms
Biogeography: the study of where organisms live now and
where they and their ancestors lived in the past
Comparative Anatomy
What do a chicken and a human have in common?
What do a shark and a dolphin have in common?
You probably first thought to compare physical
structures of each species
Comparative anatomy compares the physical,
anatomical structures of species to understand their
ancestral relationship
Homologous structures:
Structures that are shared
by related species and
have inherited from a
common ancestor
Human
Cat
Whale
Bat
Each of these organisms have similar bone structures that modified
through evolution, yet still resemble descent from a common ancestor
Comparative Anatomy Cont’d
Bats and bee’s both have wings
Is there a major difference between the wings of a bird
and the wings of a bee?
Do they do the same thing for each organism?
Structures that are similar in unrelated species are
called Analogous Structures
• They do not have common ancestry… so why do
you think they have similar structures?
• What can studying analogous structures tell us
about the evolution of certain animals?
Vestigial Structures
• Some homologous structures have lost most or all of its
function but still are present in some organisms
• For example, our appendix does not serve a significant
function in our bodies
• Vestigial Structures: structures inherited from ancestors
but have lost much or all of its original function due to
selection pressures.
Watch Hank Green’s Vestigial structures video
Comparative Embryology
According to Comparative Embryology, All vertebrate
embryos follow a common developmental path due to
their common ancestry
How does this support the theory of evolution?
Lizard
Turtle
Pig
Human
Molecular Biology
Recent evolutionary research is heavily focused on
studying ancestry at the molecular level
• Genes
• DNA
• Molecules
We can now compare the patterns found in the
genetic code and homologous molecules in different
species to help understand the missing links in
evolutionary evidence
A Common Genetic Code
All living organisms are governed by the same GENETIC
CODE which is based on the sequence of bases found in
DNA molecules
DNA is composed of sequences
of 4 different nucleotide based
Guanine (G)
Adenine (A)
Tyrosine (T)
Cytosine (C)
The sequences and amounts
of where these bases occur
differentiate proteins within
organisms
NOVA- Bird Brains
Investigate how molecular biology can help
understand the evolutionary relationship between
two organisms such as Humans and Birds
Watch Bird Brains
Complete Bird Brains Activity
Bird Brains Follow Up Activity
• The protein Cytochrome C is found in many different
species
• Different species have different DNA sequences which
produce different sequences and amounts of amino acids
within proteins
• Find the differences in the cytochrome C protein of
several organisms, comparing it to the Human
Cytochrome C protein
• PREDICT: which organism do you think will be more
closely related to humans based on this molecular
evidence?