EVOLUTION & NATURAL SELECTION. Figure 13.16 PEPPERED MOTH

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