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EVOLUTION & NATURAL SELECTION
Figure 13.16
PEPPERED MOTH
PEPPERED MOTH ON TREE
VARIATION OF COLOR IN THE POPULATION
VARIATION !!!!
• Variation within species means some individuals will have traits better equipped to deal with life’s selective pressures
2 peppered moths on a dark tree
✕
• Because nature (the bird) selected the favorable trait (in this case, color) we call it…
NATURAL SELECTION
NATURAL SELECTION – LETS SPECIES BECOME BETTER FIT TO THEIR ENVIRONMENT AS THEY RESPOND TO SELECTION PRESSURES
ALL LIFE ON EARTH IS UNDERGOING NATURAL SELECTION ALL THE TIME
• BUGS• TREES
• PEOPLE• ANIMALS• JELLYFISH
• ETC…
ARTIFICIAL SELECTION
• ARTIFICIAL SELECTION = mankind choosing favorable traits (NOT NATURE choosing) to fit our desires
NATURE SELECTING + TIME = EVOLUTION
• If we say evolution is occurring we need evidence. One such evidence is comparing anatomy (or body parts) of different kinds of life.
• Similar body parts = closely related
• Different body parts = distantly related
Comparative Anatomy
Comparative anatomy - the comparison of body structure
Figure 13.11
3 Homologous Structures . . (Related)
3A
nalo
gous
st
ruct
ures
NOT RELATED
Comparative Anatomy
–Homologous (as in the same)• Is the similarity in structures due to common ancestry.
–Analogous (as in analogy)•Similar only in function NOT common ancestry
• CLASS WORK• “Why have certain bacteria become resistant
to antibiotics?”
THIS BONE FLUTE IS 11,400 YEARS OLD
•Q: If we weren’t there to see it how do we know how old
something is?
•A: Carbon 14 dating (C14)
–Carbon 14 dating = Counting the amount of C14 in an old object•Used to establish age of object
•Done by counting “half lives”Half life = the amount of time
necessary for an unstable atom to go back to half stable (C14 HL= 5,700yrs)
This is the atom carbon
6 protons +
6 neutrons12
This is Carbon 12 or (C12)
This is the atom carbon
6 protons +
7 neutrons13
This is Carbon 13 or (C13)
7
This is the atom carbon
6 protons +
8 neutrons14
This is Carbon 14 or (C14)
8
HOW C14 IS MADE•The sun’s rays hit the atmosphere at a consistent and measurable rate since the Earth has been here.
The effect the suns rays have on the atmosphere is also consistent and measurable
Both carbon and neutrons are in the atmosphere. When neutrons get smacked with this solar radiation they stick to the normal carbon
HOW C14 GETS INTO ANY LIFE FORM
• •C12 is stable •C13 is unstable (radio active)•C14 is really unstable (radio active)•AND unstable C14 really wants to decay back down to stable C12
•HOW CARBON 14 DATING WORKS
•http://www.youtube.com/watch?v=31-P9pcPStg
This pie represents 100% of all the C14 in a living organism
C14
After 5,700 years, exactly half of the C-14 is left while the rest decays back
into C12
C14 C12
THIS IS 1 HALF LIFE
After another 5,700 years exactly half of the last half of C-14 is left.
Leaving 1/4
C14 C12
THIS IS __ HALF LIVES2
After another 5,700 years
THIS IS __ HALF LIVES3
C14 C12
After another 5,700 years
THIS IS __ HALF LIVES4
C12C14
•Since we know how much C14 is in a living animal…and
•We know the exact rate that C14 decays…
• we can determine how old an artifact / bone is from measuring
the amount of C14 left in it
Carbon 14 CHART
Half lifeYears old
(total)Fraction of C14
remaining
1 5,700 1/2
2 11,400 1/4
3
417,100 1/8
22,800 1/16
Figure 14.17b
The clam shell being dug up (#3) has 1/32 the amount of C14 we expected to find in a living clam.
Q: How many years old is it?
Half lifeYears old
(total)Fraction of C14
remaining
1 5,700 1/2
2 11,400 1/4
3
4
5
17,100 1/8
22,800 1/16
1/3228,500
Figure 14.17a
Q: SO WHAT FRACTION OF C14 WAS LEFT IN THE FLUTE?
A: ¼
This flute is 11,400 years old
Grouping Species: The Basic Concept
–Taxonomy is the branch of biology that names and classifies species.• It makes sense of all life by organizing like with like
•EARTH IS 4.5 Billion Years Old•LIFE IS 3.5 BYO
Figure 1.8
ALL LIFE
Domain
Kingdom
Prokaryote(NO TRUE NUCLEUS)
Eukaryote(TRUE NUCLEUS)
BacteriaArchaea
PlantaeFungi
AnimaliaProtista
kingdom FUNGI
order Yeast mold mushrooms
– Bacteria and Archaea are both in the prokaryotic domain.
Figure 1.9.1
Figure 1.9.2
– Eukaryotes includes at least four kingdoms:• Plantae• Fungi• Animalia• Protists
– (Multiple kingdoms)
Figure 1.9.2
Eukaryotes can look like all these
• WHICH GROUP IS THE SMALLEST (OR MOST SPECIFIC)? –KINGDOM–GENUS–SPECIES–CLASS
• WHICH GROUP IS THE BIGGEST (OR LEAST SPECIFIC)? –KINGDOM–GENUS–SPECIES–CLASS
