Evidence for Evolution

Evidence Supporting EvolutionEvidence Supporting Evolution

Fossil recordFossil record• shows change over timeshows change over time

Anatomical recordAnatomical record• comparing body structurescomparing body structures

homology & vestigial structureshomology & vestigial structures embryology & developmentembryology & development

Molecular recordMolecular record• comparing protein & DNA sequencescomparing protein & DNA sequences

Artificial selectionArtificial selection• human caused evolutionhuman caused evolution

Fossil RecordFossil Record Layers of rock contain fossils Layers of rock contain fossils

• new layers cover older onesnew layers cover older ones creates a record over timecreates a record over time

• fossils show a series of organisms have lived fossils show a series of organisms have lived on Earth on Earth

over a long period of timeover a long period of time

Fossils Tell A StoryFossils Tell A Story

the Earth is oldthe Earth is old

Life is oldLife is old

Life on Earth has changedLife on Earth has changed

Fossil of Fossil of ArchaeopteryxArchaeopteryx lived about 150 myalived about 150 mya links reptiles & birdslinks reptiles & birds

Today’s organisms Today’s organisms descended from descended from

ancestral speciesancestral species

Today’s organisms Today’s organisms descended from descended from

ancestral speciesancestral species

Evolution of BirdsEvolution of Birds

Land Mammal

?

???

Where are the

intermediate

fossils?Where are the

intermediate

fossils?

Ocean Mammal

Someone’s idea of a joke!

But the joke’s on them!!

Complete seriesof transitional

fossils

We found the fossil — no joke!

Evolution from Sea to LandEvolution from Sea to Land 2006 fossil discovery of early tetrapod2006 fossil discovery of early tetrapod

• 4 limbs4 limbs Missing link from sea to land animalsMissing link from sea to land animals

Anatomical RecordAnatomical Record

On the outside, animals may look different. , But when you look under the skin…

It tells an evolutionary story of common ancestors

Anatomical RecordAnatomical Record

The same bones under the skinThe same bones under the skin• limbs that perform limbs that perform different functionsdifferent functions are built are built

from the from the same bonessame bones

How could these different

organisms have the same bones?

Homologous StructuresHomologous Structures Structures that come from the same Structures that come from the same

originorigin homo- = samehomo- = same -logous = information-logous = information

Forelimbs of human, cats, whales, & bats Forelimbs of human, cats, whales, & bats • same structuresame structure

on the insideon the inside

• same development in embryo same development in embryo • different functionsdifferent functions

on the outsideon the outside

• evidence of common ancestorevidence of common ancestor

But Don’t Be Fooled By These…But Don’t Be Fooled By These…

Analogous structuresAnalogous structures• look similarlook similar

on the outsideon the outside

• same functionsame function• different structure & developmentdifferent structure & development

on the insideon the inside

• different origindifferent origin• no evolutionary relationshipno evolutionary relationship

How is a bird like a bug?

Analogous StructuresAnalogous Structures Dolphins: Dolphins: aquatic mammalaquatic mammal Fish: Fish: aquatic vertebrateaquatic vertebrate

• both adapted to both adapted to life in the sealife in the sea

• not closely relatednot closely related

Watch the tail!

Convergent evolutionConvergent evolution 3 groups with wings3 groups with wings

• Does this mean they have a Does this mean they have a recent common ancestor?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!

Convergent evolution led to Convergent evolution led to mimicrymimicry Why do these pairs look so similar?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?

Vestigial organsVestigial organs

Hind leg bones on whale fossilsHind 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!

Comparative embryologyComparative embryology Development of embryo tells an Development of embryo tells an

evolutionary story evolutionary story • similar structures during developmentsimilar 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

3. Molecular record3. Molecular record

100 20 30 40 50 60 70 80 90 100 110 120

LampreyFrogBirdDogMacaqueHuman

328 45 67 125

Comparing DNA & protein structureComparing DNA & protein structure• everyone uses the same genetic code! everyone uses the same genetic code!

DNADNA

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

Building “family” treesBuilding “family” treesClosely related species are branches on the tree — Closely related species are branches on the tree — coming from a common ancestorcoming from a common ancestorClosely related species are branches on the tree — Closely related species are branches on the tree — coming from a common ancestorcoming from a common ancestor

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

4. Artificial selection4. Artificial selection

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

Selective BreedingSelective BreedingHumans create the change over timeHumans create the change over time

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

Artificial Selection gone bad!Artificial Selection gone bad!

Unexpected Unexpected consequences of consequences of artificial selectionartificial selectionPesticide resistancePesticide resistance

Antibiotic resistanceAntibiotic resistance

Insecticide resistance Insecticide resistance

Spray the field, but…Spray the field, but…• insecticide didn’t insecticide didn’t

kill all individualskill all individuals variationvariation

• resistant survivors resistant survivors reproducereproduce

• resistance is inheritedresistance is inherited• insecticide becomes less & insecticide becomes less &

less effectiveless effective

Any Questions??Any Questions??

Niche 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

Parallel EvolutionParallel Evolution

marsupial mammal

placental mammal

filling similar roles in nature, filling similar roles in nature, so have similar adaptationsso have similar adaptationsfilling similar roles in nature, filling similar roles in nature, so have similar adaptationsso have similar adaptations

not closely relatednot closely related

Vestigial organsVestigial organs Structures on modern animals that have no Structures on modern animals that have no

functionfunction• remains of structures that were functional in remains of structures that were functional in

ancestorsancestors

• evidence of change over timeevidence of change over time some snakes & whales have pelvis bones & leg some snakes & whales have pelvis bones & leg

bones of walking ancestorsbones of walking ancestors eyes on blind eyes on blind

cave fishcave fish human tail bonehuman tail bone