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Activating Strategy• Create a caption for this picture based on what

you know about evolution

AP Lesson #61

EQ: What evidence helps support

Charles Darwin and Evolution?

What evidence supports evolution?

• Fossil record

• Anatomical record

• Molecular record

• Artificial selection

How is the fossil record evidence of evolution?

• Layers of sedimentary

rock contain fossils

– fossils show a succession of

organisms over a long period of time

– Indicates transitional

species

– Provides evidence

that today’s organisms descended

from ancestral

Fossil Record Evolutionary change in horses

Millions of years ago

50

100

150

200

250

300

350

400

450

500

550

60 55 50 45 40 35 30 25 20 15 10 5 0

Equus

HyracotheriumMesohippus

Merychippus

Nannippus

Bo

dy

siz

e (

kg

)

2

?

?

?

?Where are the

transitional

fossils?

Land Mammal

How does anatomy show evolutionary relationships?

• Homologous structures

– similarities in characteristics resulting from common ancestry

What do homologous structures indicate?

• Similar structure and development but different

functions

• Evidence of close evolutionary relationship

– recent common ancestor

Do all similar structures mean a close

evolutionary relationship?

• NOPE!

• Analogous structures

– similar external form (function)

• Separate evolution of structures

– different internal structure & development

– no evolutionary relationship

Solving a similar problem with a similar solution

Solving a similar problem with a similar solution

So then what type of evolution is this?

• Convergent evolution

– evolved similar “solution” to similar “problems”

What is parallel evolution?• Type of convergent evolution where organisms fill

similar ecological roles in similar environments

• Similar adaptations were selected

– not closely related

marsupial mammals

marsupial mammals

placental mammals

placental mammals

3

Parallel types across continentsNiche Placental Mammals Australian Marsupials

BurrowerMole

Anteater

Mouse

Lemur

Flyingsquirrel

Ocelot

Wolf Tasmanian “wolf”

Tasmanian cat

Sugar glider

Spotted cuscus

Numbat

Marsupial mole

Marsupial mouse

Anteater

Nocturnalinsectivore

Climber

Glider

Stalkingpredator

Chasingpredator

What about structures that organisms have but don’t use?

• Vestigial Organs– structures that serve little or no function today but

were functional in ancestral species

– deleterious mutations accumulate in genes for non-critical structures without reducing fitness

How is embryology evidence of evolution?

• Comparative embryology

– Similar embryological development in closely

related species

How can molecular genetics support evolution?

0 25 50 75 100 1250

25

50

75

100

Millions of years ago

Horse/donkey

Sheep/goat

Goat/cow

Llama/cow

Pig/cow

Rabbit/rodent

Horse/cow

Human/rodent

Dog/cow

Human/cow

Human/kangaroo

Nu

cle

oti

de s

ub

sti

tuti

on

s

• Comparing DNA & protein

structure (universal)

– compare common genes

• cytochrome C(respiration)

• hemoglobin (gas exchange)

Closely related species have sequences that are more similar than distantly related species

Closely related species have sequences that are more similar than distantly related species

Comparative Hemoglobin Structure

100 20 30 40 50 60 70 80 90 100 110120

LampreyFrogBirdDogMacaqueHuman

328 45 67 125

Number of amino acid differences betweenhemoglobin (146 aa) of vertebrate species and that of humans

Number of amino acid differences betweenhemoglobin (146 aa) of vertebrate species and that of humans

4

How does artificial selection occur?

• Insecticide &

drug resistance

– insecticide didn’t kill all individuals

– resistant survivors

reproduce

– resistance is inherited

– insecticide becomes less & less effective

Summarizing Strategy• Evolution Acrostic

– Create a sentence for each letter in the word that has something to do with what you learned today.

E

V

OL

UT

IO

N

Assessment

• HW: Chapter 22.3 wkst