Transcript Evolution Theory by Natural selection - KCI-SBI3U

Evidence for Evolution (Cont’d)
1.
2.
3.
4.
5.
6.
The Fossil Record
Biogeography
Anatomy
Embryology
Molecular Biology
Artificial Selection (last class)
Watch this: http://www.youtube.com/watch?v=faRlFsYmkeY
3. Anatomical Evidence
Homologous Body Structures
• Helps biologists group animals according
to how recently they shared a common
ancestor
• Dolphins look more like fish but their
homologies show they are mammals.
They have lungs rather than gills and
obtain oxygen from air, not water. (evolved
from land mammals, not fish)
Homologous Body Structures
• similar structures inherited from a
common ancestor that have different
functions in modern species
humerus
Similar
in
ulna
number
radius
and
arrange
-ments metacarpals
phalanges
Analogous Body Structures
• Structures of organisms that are not from a
common ancestor but perform similar functions
These wings are for flying but
have different structures
Homology
vs.
Analogy
Homology: traits inherited by two different organisms from a common ancestor
Analogy: similarity due to convergent evolution, not common ancestry
Vestigial organs
- remains of a structure that was once functional (e.g.
human tailbone)
• The presence of the organ does not affect its ability to
survive and reproduce, so natural selection does not
eliminate it
• demonstrates evidence of change over time
Cave fish with no eye
Pig feet- toes never touch the
ground
Vestigial organs: evolutionary baggage
Vestigial Structures
• Examples: wings on flightless birds,
human coccyx and appendix
The appendix, for
instance, is believed to
be a remnant of a larger,
plant-digesting structure
found in our ancestors.
4. Evidence from Embryology
• All vertebrates embryos develop
similarly
• Similar genes that define their
basic body plan
• We have ‘tails’ as embryos
Which is the
human embryo?
PIG FETUS
Answer: All of
them except the
one above,
which is a pig.
5. Evidence from Molecular Biology
• All organisms use
DNA and RNA to
transmit genetic
information
• ATP is an energy
carrier in all
organisms.
• Similar amino acid
sequences in proteins
Human and Chimp Karyotype
idiogram
BIOCHEMICAL EVIDENCE
DNA, Amino Acids, Cytochrome C, hemoglobin are similar
in related organisms
Comparative hemoglobin structure
Human Macaque
8
Dog Bird
Frog
Lamprey
32 45
67
125
0 10 20 30 40 50 60 70 80 90 100 110 120
Number of amino acid differences between
hemoglobin (146 aa) of vertebrate species and that of humans
STSE- A Chickenosaurus ?!
Hans Larsson,
Canada
Research Chair
in MacroEvolution at
Montreal's
McGill
University
"If I can demonstrate clearly that the potential for dinosaur
anatomical development exists in birds, then it again proves
that birds are direct descendants of dinosaurs."
http://www.ted.com/ta
lks/lang/en/jack_h
orner_building_a_
dinosaur_from_a_
chicken.html
To ponder: Adaptation?
• http://www.youtube.com/watch?v=NOjFA4V_Ks4
Uhm, what
evidence
would falsify
my evolution
theory?
Think about it
kids.
Homework
• Read pg. 296-302
• Pg. 303 #4-7
• Pg. 303 #1 and 2
Consolidation
• Summarize the various kinds of evidence
for evolution (i.e., that all living organisms
descended from a common ancestor)
• Remember: Population evolve;
Individuals do not