Ch 15 evolution 1 8-2013
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Transcript of Ch 15 evolution 1 8-2013
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