Download Theory of Evolution Unit

Evidence for Evolution
1.
2.
3.
4.
5.
Fossils
Geography
Embryology
Anatomy
Molecular
Fossil Evidence
1. Fossils are traces of
organisms that existed in
the past
2. Fossils found in deeper
layers of rock are older
than the top layers
3. More primitive organisms
in deeper layers
4. Fossil record updated as
new fossils are found
(fossils record a historical
sequence of change)
Fossils
1. Top layer
a. Newer
b. Younger
c. Most forms alive today
d. Most complex species
2. Bottom layer
1. First formed
2. Older
3. Least complex species
3. Same layers = Same age
Geography Evidence
1. Different environments favor different traits;
the result is local adaptation
2. Scientists study biogeography, the study of
organism distribution around the world
Embryology Evidence
1. Larvae of many
organisms similar
2. Vertebrate embryos
have some similarities
a. Embryonic gill slits in
fish, birds, reptiles, and
mammals
Anatomy Evidence
A. Three Types:
1. Analogous structures
2. Homologous structures
3. Vestigial structures
Anatomy Evidence
1. Analogous Structures
a. Parts that evolved independently and yet serve
the same function.
b. Supports convergent evolution.
c. Example: Wings of birds and insects…. Both are
used for flight but evolved on different paths.
Anatomy Examples
• Analogous Structure Examples
Analogous Structures
• Examples
Anatomy Evidence
2. Homologous structures
2. Physical characteristics in different organisms
that are similar because it was inherited from a
common ancestor.
3. Add to notes: ancestral structures have been
modified to new functions.
a. Examples: forearm of humans, penguin and
bats.
Anatomy Evidence
• Homologous Structures Examples
Anatomy Evidence
3. Vestigial Structures
a. Physical characteristics in organisms that appear
to have lost their original function as a species
has changed over time.
b. Sometimes only remnants remain
c. Add to notes: remnants of past important
features from ancestor
d. Examples: appendix and coccyx in humans, the
“hip bones” in pythons and whales.
Anatomy Evidence
• Vestigial Structures Examples
Molecular Evidence
1.
Universal genetic code
a. 20 amino acids found in
organisms
b. DNA sequence analysis shows
that the more closely related
organisms are, the more DNA
they share
c. More traits in common= more
proteins the same = similar
RNA = similar DNA= share a
common ancestor
Human % shared genes
Chicken = 60%
cow 80%
Fruit fly = 60 %
cat 90 %
Mouse = 75%
chimpanzee 96-98%