• For this ppt, have the moth simulation ready

• Have blind spot test ready

Chapter 22Evidence for Evolution

• How has evolution risen in status to the level of THEORY, the same level as gravity or plate tectonics?

• Through repeated observations from many areas of life sciences.

Evolution Objectives

• If given the statement, “There is little evidence for evolution,” be able to respond using measurable evidence.– Fossil evidence– Anatomical Evidence– Molecular Evidence

• Describe the contributions of Charles Darwin and explain how Hutton and Lyell informed Darwin’s understand of Evolution

Evidence of Evolution

• What is probably the first evidence that living things have changed over time?

• What additional clues have been added since then?

Beaks as Evidence pg 457

• Darwin saw finches on the Galapogos Islands (and tortoises… and armadillo fossils in South America, and lots more).

• What did he notice about these finches?• “ …from an original paucity of birds in this

archipelago, one species has been…modified for different ends.” Can someone rephrase this?

• Are you able to see things in a different way than they have traditionally been seen?

Grants’ Modern Observations Support Darwin’s Hypthesis

• The Grants did measurable experiments to measure characteristics such as beak size.

• Details on following slide

Figure 23.2

1976(similar to theprior 3 years)

1978(after

drought)

Ave

rag

e b

eak

dep

th (

mm

)

10

9

8

0

Figure 22.2

1809

1798

1812

1795

1830

17901809 183136

1844

18591870

Lamarck publishes hishypothesis of evolution.

Malthus publishes“Essay on the Principle

of Population.”

Hutton proposeshis principle of

gradualism.

Charles Darwinis born.

Darwin travels around the world on HMS

Beagle.

The Galápagos Islands

Darwin writes his essay on descent with modification.

On the Origin of Species is published.

While studying species in the Malay Archipelago, Wallace (shown in 1848)sends Darwin his hypothesisof natural selection.

1858Cuvier publishes his extensive studies of vertebrate fossils.

Lyell publishesPrinciples of Geology.

Geology informs Darwin

• Geologists James Hutton and Charles Lyell perceived that changes in Earth’s surface can result from slow continuous actions still operating today

• Lyell’s principle of uniformitarianism states that the mechanisms of change are constant over time

• This view strongly influenced Darwin’s thinking

Industrial Melanism

• Industrial Revolution and the Peppered Moth

• How does this relate to the Clean Air Act?

• See peppered moth simulation

• What types of selection can you attribute this to?

Figure 53.22

The Plague

Hu

man

po

pu

lati

on

(b

illio

ns)

8000BCE

4000BCE

2000CE

1000BCE

2000BCE

3000BCE

1000CE

0

7

6

5

4

3

2

1

0

Industrial Melanism

• Industrial Revolution and the Peppered Moth

• How does this relate to the Clean Air Act?

• See peppered moth simulation

• What types of selection can you attribute this to?

Selection Ponderables

• Does selection act directly on genotypes or phenotypes?

• Which is more likely to be selected against, deleterious mutations that are dominant or those that are recessive? Why?

• Can selection create perfect organisms?– (Human’s backs are evolved from 4-legged

ancestors and not fully compatible w upright posture, so many older people have backpain)

• Blind Spot Test- (See Class Set Handout)

Fossil Evidence

• How can the age of fossils be determined?– Relative Dating– Absolute Dating

Figure 22.3

Sedimentary rocklayers (strata)

Younger stratumwith more recentfossils

Older stratumwith older fossils

Fossil Evidence

• We found orange juice with 1/8 of its original 32P in the lab cabinets during cleanup. 32P has a half-life of about 14 days.

How long had the orange juice been there?

• That is 3 half-lives, so about 3 x 14= 42 days. Drink Up!

Anatomical Evidence

• Homologous structures– Structures that have different functions but

arrived from same body part.– Human arm, bat wing, porpoise flipper

Figure 22.15

Humerus

Radius

Ulna

Carpals

MetacarpalsPhalanges

Human Cat Whale Bat

Homolgous Structures

Figure 22.20

Other even-toedungulates

Hippopotamuses

†Pakicetus

†Rodhocetus

†Dorudon

Livingcetaceans

Commonancestorof cetaceans

Millions of years ago

70 Key60 50 40 30 20 10 0 Pelvis TibiaFemur Foot

Phylogenetic Tree

Did you know there are pelvic bones in snakes? In whales? Why?

They are vestigial structures

What vestigial structures do humans have?

Appendix

Ankle bone of cetaceans – page 465

• What are cetaceans?

• Mammal group including whales, dolphins, and porpoises.

• Fossils of Pakicetus show that it had an ankle bone with characteristics like that of an even toed ungulate (deer or pig).

Figure 22.19

Most mammals Cetaceans and even-toed ungulates

(a) Canis (dog) (b) Pakicetus (c) Sus (pig) (d) Odocoileus (deer)

Embryological Evidence

• Findings from Development– “Ontogeny recapitulates phylogeny”.– Developing embryo tells a story

• gill pouches, tail, fur (lanugo)

Figure 22.16

Pharyngealpouches

Post-analtail

Chick embryo (LM) Human embryo

Embryological Evidence

http://www.exploratorium.edu/exhibits/embryo/embryoflash.html

Which Embryo is Which? Click Link:

Darwinian Prediction

• Darwin found an orchid whose reproductive organs were 30 cm deep inside the flower.

• Darwin postulated that a pollinator would be found with a 30 cm proboscis.

• It took 40 years, guess what scientists found!...

Darwinian Prediction

• Xanthopan morganii praedicta– The Hawk Moth

– Guess the length of the proboscis?

– Notice its last name?

– What kind of logic?

• Inductive or deductive?

• What our new understanding of genetics tell us about our model of evolution?

Molecular Record

• The more amino acid (or DNA base pair) differences, the greater the evolutionary distance.

• The ‘trunk’ of the tree represents similar traits or molecules (depending on how tree was made). Each branch represents a divergence.

Convergent Evolution

• Two separate groups (branches on evolutionary tree) display similar characteristics.

• Analogous Structures

• Ex: Placental mammals often have a marsupial “cousin”: wolf / tasmanian “wolf”.

Evolution of Drug-Resistant Bacteria

• The bacterium Staphylococcus aureus is commonly found on people

• One strain, methicillin-resistant S. aureus (MRSA) is a dangerous pathogen

• S. aureus became resistant to penicillin in 1945, two years after it was first widely used

• S. aureus became resistant to methicillin in 1961, two years after it was first widely used

• We will discuss in class next quarter.

Island Evolution

• An ideal location to study evolution. Organisms can be seen that are similar to the mainland species that they are nearest, but with traits adapted to a specific island.

Illustrative Examples

• Number of heart chambers in animals

• Opposable thumbs

Many apes, oppossums, koalas, pandas. Some birds have opposable digits, as did some dinosaurs.

• Absence of legs in some sea mammals– Whale’s have a pelvic bone, even though they

have no legs.

Species that lack diversity are at risk for extinction

• Can you think of examples?

• Corn- Corn Rust Disease• Potatoes- Irish Potato Famine changed history• California condors- prone to epidemic disease• Prairie chickens- once numbering in the millions-

now only about 60 left in the wild• Tasmanian Devil- We will read up on this

Evolution Objectives

• If given the statement, “There is little evidence for evolution,” be able to respond using measurable evidence.– Fossil evidence– Anatomical Evidence– Molecular Evidence

• Describe the contributions of Charles Darwin and explain how Hutton and Lyell informed Darwin’s understand of Evolution