Transcript Evolution: Adaptation

Evidence for
Evolution
I. Evidence for Evolution
A. Fossils
B. Molecular Evidence
C. Homologous structures
D. Vestigial structures
E. Mimicry
F. Camouflage
A . Fossils
1. Shows that
life is old
and has
changed over time
2. Illustrates
evolutionary change
over past 4 billion
years
Fossils
B. Molecular Evidence for
Evolution
1. When comparing DNA or amino acid
sequences, the species with the most
similar DNA are most closely related.
2. Number of Differences in Partial
Hemoglobin DNA Sequences
Frog
Chicken
Goat
Cow
Chimp
Human
Frog
-
13
10
10
10
10
Chicken
-
-
6
7
5
5
Goat
-
-
-
1
1
1
Cow
-
-
-
-
2
2
Chimp
-
-
-
-
-
0
Human
-
-
-
-
-
-
2. Number of Differences in
Partial Hemoglobin DNA
Sequences Cont.
a. Humans are most closely related to chimpanzees
• differences in hemoglobin DNA sequence
0__
__
b. Humans are least related to frogs
• differences in hemoglobin DNA sequence
•
10
C . Homologous Structures
1. Same structure in different organisms
that may have evolved to have different
functions.
2. They all have the same structure from a
common ancestor.
3. Example
a. Same types of bones
•
•
•
•
•
•
Humerus (upper arm)
Radius (lower arm)
Ulna (lower arm)
Carpals (wrist)
Metacarpals (hand)
Phalanges (fingers)
b.
C.
4. . Analogous Structures
a. Have the same function but not the same structure and did
not evolve from a common ancestor.
• Organisms that live in the same environment may
evolve similar adaptations
• Organisms with similar adaptations may evolve from
different ancestors
b. Examples:
• Sharks and Dolphins
• Wings (birds, bats, butterflies)
4. Analogous Structures Cont.
Sharks and dolphins are NOT closely related
(Dolphins are more closely related to humans than sharks)
Evolved similar adaptations because they live in a similar environment
Analogous Structures
b.
Wings of butterflies, bats, and
birds have same function – flight.
Evolved the ability to fly from
different ancestors.
D. Vestigial structures
• Are structures that were used in a common ancestor, but are
disappearing over time in current species because they are no
longer needed
• Examples:
• Appendix in humans
• Wisdom teeth in humans
• Hip bone in whales
E. Mimicry 1. Looking like another species that may pose a threat to
predators
2. Examples:
Mimicry Examples a.
Coral Snake - Venomous
King Snake – not venomous
Mimicry Examples b.
Monarch and Viceroy
Monarch Butterfly (poisonous) and Viceroy Butterfly (not
poisonous)
F. Camouflage 1. Looking similar to the
environment to avoid predators
2. Examples:
Camouflage Example a.
Camouflage Example b. Bird
Camouflage Example c. Frog
Camouflage Example
d. Walking stick
Camouflage Example
e. Praying Mantis
Camouflage