2006-2007

Insect eaters

Bud eater

Seed eaters

Cactuseater

Warbler

finch

Tree

finc

hes G

round finches

A. Proposed a way how evolution works

1. How did creatures change over time?

2. By natural selectionB. Collected a lot of

evidence to support his ideas

1. 1809-18822. British naturalist

Robert FitzroyRobert Fitzroy

A. Darwin invited to travel around the world

• 1831-1836 (22 years old!)• made many observations of nature• mission of the Beagle was to chart

South American coastline

B. Explored Galapagos Islands• 500 miles off coast of Ecuador

Recently formed volcanic islands. Most of animals on the Galápagos live nowhere else in world, but they look like species living on South American mainland.

800 km west of Ecuador

Many of Darwin’s observations made him wonder… Why?Many of Darwin’s observations made him wonder… Why?

Why were these creatures found only on the Galapagos Islands?

present day Armadillos

Evidence showed that Evidence showed that creatures had changed creatures had changed over timeover time

ancient Armadillo

Darwin asked:Darwin asked:

Why should extinct Why should extinct armadillos & modern armadillos & modern armadillos be found on armadillos be found on same continent?same continent?

present day Sloth

Darwin asked:Darwin asked:

Why should Why should extinct sloths & extinct sloths & modern sloths be modern sloths be found on the same found on the same continent?continent?

(extinct) Giant ground sloth

Evidence showed that Evidence showed that creatures had changed creatures had changed over timeover time

Darwin found...different shells on Darwin found...different shells on tortoises on different islandstortoises on different islands

Darwin asked:Darwin asked:

Is there a relationship Is there a relationship between the between the

environment & what an environment & what an animal animal

looks like?looks like?

He He thoughtthought he he

found many found many

different kinds...different kinds...

Darwin was amazed to find out:

All 14 species of birds were finches…But there is only one species of finch on the mainland!

QuickTime™ and aPhoto - JPEG decompressor

are needed to see this picture.Finch? Sparrow?

Woodpecker? Warbler?

Darwin asked:Darwin asked:

If the Galapagos finches If the Galapagos finches came from the mainland, came from the mainland, why are they so different why are they so different

now?now?

Darwin found: The differences between species of finches were associated with the different food they ate.

different beaks are inherited variations

serve as adaptationsthat help birds compete for food

these birds survive & reproduce

pass on the genes for those more fit beaks

over time nature selected for different species with different beaks

Warbler finch

Woodpecker finch

Small insectivorous

tree finch

Largeinsectivorous

tree finch

Vegetarian tree finch

Cactus finch

Sharp-beaked finch

Small groundfinch

Mediumground finch

Large groundfinch

Insect eaters

Bud eater

Seed eaters

Cactuseater

Warbler

finch

Tree

finc

hes G

round finches

variationnatural selection for best survival & reproduction

A. Darwin’s conclusions 1. Variations in beaks

in original flock adaptations to foods available on islands

2. Natural selection for most fit over many generations finches were selected for specific beaks &

behaviors

3. Offspring inherit successful traits over many generations finches were selected for specific

4. Separate into different species

LaMarck• evolution by acquired

traits creatures developed traits

during their lifetime give those traits to their

offspring

• example in reaching higher

leaves giraffes stretch their necks & give the acquired longer neck to offspring

• not accepted as valid

Giraffes that already

have long necks survive better

Leave more offspring that inherit long necksvariationselection & survival

reproduction & inheritance of

more fit traits

A. Fossil record Shows change over time

B. Anatomical record Comparing body structures

1. homology & vestigial structures2. embryology & development

C. Molecular record Comparing protein & DNA

sequencesD. Artificial selection

Human caused evolution

Layers of rock contain fossils new layers cover older ones creates a record over time

fossils show a series of organisms have lived on Earth over a long period of time

the Earth is oldthe Earth is old

Life is oldLife is old

Life on Earth has changedLife on Earth has changed

In 2006 fossil discovery of early tetrapod4 limbs

Missing link from sea to land animals?

Land Mammal

?

??

Where are the

intermediate

fossils?Where are the

intermediate

fossils?

Ocean Mammal

Complete seriesof transitional

fossils

We found the fossil — no joke!

Fossil of Archaeopteryx lived about 150 mya links reptiles & birds

Today’s organisms descended from ancestral species

Today’s organisms descended from ancestral species

Animals with different structures on the surfaceAnimals with different structures on the surface

But when you look under the skin…But when you look under the skin…

It tells an evolutionary story of common ancestorsIt tells an evolutionary story of common ancestors

The same bones under the skinlimbs that perform different functions

are built from the same bones

How could thesevery different animals

have the same bones?

Structures that come from the same origin

Homo = same logous = information

Forelimbs of human, cats, whales, & bats are homologous

same structureon the inside

same development in embryo different functionson the outside

evidence of common ancestor

Don’t be fooled by these! look similar

on the outside same function different structure &

development on the inside

different origin no evolutionary relationship

Solving a similar problem with a similar solutionSolving a similar problem with a similar solution

How is a birdlike a bug?

Dolphins: aquatic mammal Fish: aquatic vertebrate

both adapted to life in the sea

not closely related

3 groups with wings• Does this mean they have a

recent common ancestor?

Flight evolved 3 separate times — evolving similar solutions to similar “problems”

Flight evolved 3 separate times — evolving similar solutions to similar “problems”

NO!

They justcame up with the

same answer!

Why do these pairs look so similar?

Monarch malepoisonous

Viceroy maleedible

fly bee moth bee

Which is the fly vs. the bee?Which is the moth vs. the bee?

Hind leg bones on whale fossils

Why would whales have pelvis & leg bones if they were always sea creatures?

Why would whales have pelvis & leg bones if they were always sea creatures?

Because they used to

walk on land!

Structures on modern animals that have no function•remains of structures that were

functional in ancestors•evidence of change over time some snakes & whales have pelvis bones & leg bones of walking ancestors

eyes on blind cave fish

human tail bone

Development of embryo tells an evolutionary story • similar structures during development

all vertebrate embryos have a “gill pouch” at one stage of development all vertebrate embryos have a “gill pouch” at one stage of development

Comparing DNA & protein structure• everyone uses

the same genetic code! DNA

100 20 30 40 50 60 70 80 90100110120

LampreyFrogBirdDogMacaqueHuman

328 45 67 125

compare common genes compare common proteins

compare common genes compare common proteins

number of amino acids different from human hemoglobinnumber of amino acids different from human hemoglobin

Closely related species are branches on the tree — coming from a common ancestorClosely related species are branches on the tree — coming from a common ancestor

How do we know natural selection can change a population?• we can recreate a similar process• “evolution by human selection”

“descendants” of wild mustard“descendants” of wild mustard

Humans create the change over timeHumans create the change over time

“descendants” of the wolf“descendants” of the wolf

…and the examples keep coming!

Unexpected consequences of artificial selection

Pesticide resistancePesticide resistance

Antibiotic resistanceAntibiotic resistance

Spray the field, but…•insecticide didn’t kill all individuals variation

•resistant survivors reproduce

•resistance is inherited•insecticide becomes less & less effective

2006-2007