Download AIM: How do comparative studies help trace evolution?

AIM: How do comparative studies help
trace evolution?
How do we know we are related
to chimps & gorillas?
COMMON ANCESTOR
Comparative Studies2
• Study of similarities between living
things.
• Provides evidence of a common
origin (ancestor)
Why do scientists do
comparative studies?3
To observe how closely organisms
are related to each other and see
evolutionary patterns
COMPARATIVE STUDIES4
• Who are we closely related to?
• Who are we distantly related to?
Types of Comparative Studies
• Anatomy
• Embryology
• Biochemistry
DNA and Proteins
Comparative Anatomy6
• What is anatomy?
• What do you think comparative
anatomy studies?
• Study of structural similarities
and differences in living things
HOMOLOGOUS STRUCTURES
• Do you see any similarities between these
organisms?
• How are they similar? How are they different?
Homologous Structures - similar
structures, different form & function.
Shows evolutionary relationships (they
are related).
(7)
VESTIGIAL STRUCTURES8
The appendix and the
tail bone are both
VESTIGIAL
structures. What do
they have in
common?
Vestigial structure- no
longer functions the
way it was meant to
VESTIGIAL STRUCTURES
Why would an organism possess
organs with little or no function?
Hind leg
in whales
They are remnants of structures that
may have had important functions in
ancestral species, but no clear function
in modern descendants.
ANALOGOUS STRUCTURES9
• What do these two images have in
common?
Insect Wing
Analogous Structures- similar form and
function, different internal structures.
Does not show evolutionary relationships
Divergent vs. Convergent Evolution:
Divergent Evolution- the pattern of
evolution in which species that were
once similar to an ancestral species
become increasingly different.
Divergent vs. Convergent Evolution:
Convergent Evolution- the pattern of
evolution in which distantly related
organisms evolve similar traits.
When do each of these types of
evolution occur?
Divergent Evolution occurs when
populations change as they adapt to
different environmental conditions.
Once related species now look different
Convergent Evolution occurs when
unrelated species occupy similar
environments in different parts of the
world. Unrelated species now look the
same.
Which is the gorilla, fish and
rabbit?
Comparative Embryology13
• In Comparative Embryology,
related organisms show similar
embryonic development
Comparative Biochemistry
Comparative Biochemistry compares the
DNA or Amino Acids of an organism in order
to find relationships among living things.
The more
similar the DNA
and Amino
Acids, the more
closely the two
organisms are
related.
Common Ancestor
• This evidence leads to the idea of:
• COMMON ANCESTRY
• All species living and extinct were
derived from common ancestors.
The Results of Genetic Variation:
1)Structural Change- the physical
features of an organism.
2)Functional Change- molecular or
biochemical changes affect how an
organism works. Changes in DNA often
lead to functional changes.
3)Behavioral Change- many of the
specific behaviors today have become
common because they have resulted in
greater reproductive success.