15.2 Evidence of Evolution
Evidence of Evolution
Section 15.2
Fossil Record Practice
Fossil Record
· tells us the age of the fossil,
where it lived, and what
the environment was like
when it was alive
· more primitive species in
bottom (older) layers
· more complex species in
the upper (newer) layers
· shows how species have
changed over time
Homologous Structures
· features that are similar in structure but appear in
different organisms and have different functions
· suggests common descent (ancestor)
F
E
D
C
B
A
1. What major change in environment occurred
after layers D and E?
2. What inferences can you make about lifeforms
when layer A was deposited?
3. If radioactive dating dates the rocks in layer C
as 450 million years old, what can you infer
about the age of the fossils in layer C? Layer B?
Layer D?
Analogous Structures
· structures that perform similar function but are
NOT similar in origin
· organisms do NOT share a common ancestor
Structural Patterns
· some organisms have structures that seem to lack
useful function, or no longer have a useful function
· vestigial structures - underdeveloped or unused
structures
ex. appendix, snake hip bones, goosebumps
15.2 Evidence of Evolution
1 Which type of structure suggests a
common ancestor?
2 Fins of a fish and flippers of whale look
similar, but evolved separately. They
are an example of
A
analogous
B
vestigial
A
analogous structures
C
homologous
B
vestigial structures
D
reciprocal
C
homologous structures
D
reciprocal structures
3 Whale hip bones are an example of
A
analogous structures
B
vestigial structures
C
homologous structures
D
reciprocal structures
Embryology
· embryos look
similar in early
development
· similar features
in very different
organisms suggests
evolution from a
distant common
ancestor
ex. gill slits
DNA and Macromolecules
· DNA analysis - the more
related two organisms are
the more DNA they share in
common
· related organisms have
proteins with similar amino
acid sequences...similar
DNA
human hemoglobin and
gorilla hemoglobin vary
by 1 amino acid
Geography
· island species resemble
species on nearest
mainland
· species move or migrate
· develop adaptations to
their new environment
ex. Darwin's finches
15.2 Evidence of Evolution
Adaptation
· a feature that allows an
organism to better
survive in its environment
· can lead to genetic
change in a population
over time
· increases an organism's
fitness
ex. camouflage, mimicry
4 MATA: An adaptation...
A
allows an organism to better
survive in its environment
B
causes mutations
C
D
Fitness
· ability to survive and reproduce
can lead to genetic changes over
time
increases fitness
5 MATA: Which of the following suggests a
common ancestor?
A
embryology
B
homologous structures
C
similar proteins
D
analogous structures