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Evolution
Chapters 13 and 14
CHARLES DARWIN
1809-1882
• TRIP ON THE BEAGLE
• 1830’S BEAGLE
• TOURED AROUND THE WORLD
• SPENT TIME ON THE GALAPAGOS
ISLANDS-OFF THE COAST OF ECUADOR
• TRIP LASTED 5 YEARS
• COLLECTED MANY SAMPLES, SPECIMENS
AND SENT THEM HOME
• KEPT A JOURNAL OF HIS OBSERVATIONS
FOR THE ENTIRE TRIP
• DARWIN’S OBSERVATIONS ON HIS TRIP
• HE SAW MUCH DIVERISTY IN ANIMALS
AND PLANTS AND FOUND FOSSILS OF
THINGS NO LONGER LIVING
• HE REALIZED THERE ARE AN ENORMOUS
AMOUNT OF SPECIES ON EARTH
• TODAY’S ESTIMATE-3-20 MILLION
• DARWIN WONDERED:
• WHERE DID ALL THESE SPECIES COME FROM
AND WHY DID SOME DISAPPEAR?
• MORE OBSERVATIONS OF DARWIN
• HE SAW MANY WAYS THAT ORGANISMS
SURVIVED AND REPRODUCED
• HE CALLED THIS FITNESS - PHYSICAL
TRAITS & BEHAVIORS WHICH ENABLE
ORGANISMS TO SURVIVE/REPRODUCE IN
THEIR ENVIRONMENT
• DARWIN WONDERED:
• HOW DID THESE ORGANISMS DEVELOP
STRUCTURES THAT GAVE THEM THIS
FITNESS?
• WHY WERE THERE SO MANY
TECHNIQUES TO SURVIVAL?
• DARWIN RETURNS HOME
• HE BECAME VERY POPULAR DUE TO ALL
THE SPECIMENS, SAMPLES HE SENT
BACK
• HE BECAME FRIENDS WITH CHARLES
LYELL, A GEOLOGIST
• THE AGE OF THE EARTH
• IN THE 18TH AND 19TH CENTURY
SCIENTISTS HYPOTHESISED THAT THE
EARTH IS VERY OLD, & CHANGED VERY
SLOWLY DUE TO NATURAL FORCES-WIND,
RAIN, ETC.
• SCIENTISTS SAW THAT THE EARTH MOVED &
SHIFTED
• SOME ROCK LAYERS BURY OTHERS & PUSH
APART THE SEA FLOOR
• THEY FOUND FOSSILS THAT RESEMBLED
ORGANISMS STILL ALIVE, BUT OTHERS DID
NOT
• THIS INFLUENCED DARWIN’S THINKING
ABOUT EVOLUTION
• CHARLES LYELL
• STATED, “THE EARTH MUST BE VERY OLD SINCE
GEOLOGICAL FORMATIONS ARE SLOW &
GRADUAL”
• “SCIENTISTS MUST EXPLAIN PAST EVENTS AS
PROCESSES THEY CAN OBSERVE. THIS IS HOW
THE SCIENTIFIC METHOD WORKS.”
• Charles Lyell – Principles of Geology
• A book that emphasized the great age of
earth and the principles of
uniformitarianism
• Uniformitarianism – the geological structure
of the earth resulted from cycles of
observable processes and that these same
processes operate continuously through time
• Ex. Sediment deposition in rivers
• These ideas influenced Darwin and he saw
how the same principles could apply to
organisms
• IN 1859, DARWIN’S “THE ORIGIN OF
SPECIES” IS PUBLISHED
• THIS IS 30 YRS. AFTER HIS TRIP ON THE
BEAGLE – IT WAS A RADICAL IDEA FOR THE
TIME
•
http://www.pbs.org/wgbh/evolution/darwin/index.html
• DARWIN’S BOOK CONTAINED 5 KEY
CONCEPTS
• 1.MODERN ORGANISMS ARISE
THROUGH EVOLUTION
• 2. EACH SPECIES COMES FROM A
PRECEDING ONE, THEY HAVE A
COMMON ANCESTOR. COMMON
DESCENT
• 3. FITNESS COMES FROM ADAPTATION
• 4. SUCCESSFUL ADAPTATION ALLOWS
ORGANISMS TO SURVIVE & REPRODUCE
• 5. ADAPTATION IS ANY CHARACTERISTIC
THAT INCREASES AN ORGANISM’S
FITNESS
• DO NOW
• 1. HOW LONG WAS DARWIN GONE ON
HIS TRIP?
• 2. WHAT WAS THE NAME OF HIS BOOK?
• 3. HOW DID DARWIN DEFINE FITNESS?
• Geologic Time Scale
• The geologic time scale is used by scientists
to map the timing and relationships
between events that have occurred during
the history of the Earth.
• It combines estimates of the age of
geological formations as provided by
radiometric dating techniques with the
direct evidence of sequences and events in
the rock record as assembled by geologists.
GEOLOGICAL TIME SCALE
GEOLOGICAL TIME-KEY EVENTS
• 3.6 B.Y.A.-1ST CELLS
• 580 M.Y.A.-AQUATIC PLANTS-ALGAE
• 360 M.Y.A.-BONY FISH, AMPHIBIANS,
INSECTS
GEOLOGICAL TIME-KEY EVENTS
• 245 M.Y.A.-PERMIAN EXTINCTIONMARINE ANIMALS
• 144 M.Y.A. JURASSIC-AGE OF THE
DINOSAURS
• 65 M.Y.A.-CRETACEOUS-EXTINCTION OF
DINOSOURS
GEOLOGICAL TIME-KEY EVENTS
• 65 M.Y.A –RADIATION (SPREADING) OF
MAMMALS
• 39 M.Y.A. –PRIMATES EMERGE
• 7 M.Y.A.-APELIKE ANCESTORS APPEAR
• 2.5 M.Y.A.-HUMANS APPEAR
• But how do scientists know when
certain things happened or when
certain organisms lived???
RELATIVE DATING-NOT DATING YOUR COUSIN!
• GEOLOGISTS IN THE PAST NOTICED THAT
CERTAIN TYPES OF ROCK COULD ALWAYS
BE FOUND IN THE SAME VERTICAL ORDER
• AGE OF ROCK CAN BE ESTIMATED BY THE
POSITION IN THE ROCK LAYERS
• OLDER LAYERS AT THE BOTTOM, NEWER
ON TOP
RELATIVE DATING
• Relative Dating – technique to date
fossils relative to other fossils in the
rocks
• Law of Superposition – successive layers
of rock or soil were deposited on top of
one another by wind or water
– lowest layers are the oldest
– top layers are the youngest
RADIOACTIVE DATING-YOU HAVE A GLOW ABOUT
YOU!
http://www.pbs.org/wgbh/evolution/library/03/3/l_033_01.html
• THE AGE OF ROCK CAN BE DETERMINED BY
THE ELEMENTS IT IS COMPOSED OF
• MANY ELEMENTS ARE ISOTOPESRADIOACTIVE
• THE ATOMS DECAY OVER TIME-SO…
RADIOACTIVE DATING CONT.
• WHEN THE ATOMS DECAY THIS CHANGES
THEIR CHEMICAL IDENTITY
• RADIOACTIVE DECAY CAN BE MEASURED
AS HALF LIFE
• HALF LIFE IS THE TIME IT TAKES FOR HALF
THE ATOMS TO DECAY
URANIUM 238/POTASSIUM 40
• URANIUM TURNS INTO LEAD AS IT
DECAYS - - HALF LIFE OF 4.5 BILLION
YEARS
• POTASSIUM TURNS INTO ARGON AS IT
DECAYS – HALF LIFE OF 1.3 BILLION
YEARS.
• SCIENTISTS CAN DETERMINE ROCK AGES
USING RATIOS
C14, CARBON DATING FOR ONCE LIVING
ORGANISMS
• C14 CARBON – HALF LIFE OF 5770 YEARS
• CARBON CAN EXIST AS RADIOACTIVE C14
OR NON RADIOACTIVE C12
• IN 5770 YEARS ½ THE C-14 TURNS INTO
• N-14
C14, CARBON DATING
• THEY CAN THEN DETERMINE THE AGE
OF THESE CELLS
• THIS METHOD IS ONLY GOOD FOR ITEMS
< 60,000 Y.O.
• OFTEN DATE PRE-HISTORIC HUMANS
USING THIS METHOD
DO NOW
• 1. C14 DATING IS GOOD FOR ITEMS
THAT ARE > 1MILLION YEARS OLD, True
OR False?
• 2. WHEN URANIUM DECAYS IT
BECOMES_______?
• 3. WHAT IS THE DEFINITION OF HALF
LIFE?
• 4. MOST FOSSILS ARE MADE FROM
RELATIVE DATING OF FOSSILS
• IF A FOSSIL IS IN A TOP LAYER-IT MUST BE?
• IF A FOSSIL IS IN A BOTTOM LAYER IT MUST
BE?
• CAN EXACT AGE BE DETERMINED WITH THIS
METHOD?
The fossil record shows that change
followed change on earth.
Fossils
• Found in the rocks
• Preserved ancient remains of organisms
• Some fossils looked like organisms that were
alive – others did not
• The fossil record shows animals that were
preserved by being buried in the rocks, tar pits
or tree sap
• Sedimentary rock-layers of sediment cover up
the animals and preserve the remains
FOSSIL RECORD-INFORMATION OF PAST FORMS OF LIFE
• TELLS OF MAJOR CHANGES IN THE
GEOLOGICAL RECORD OF EARTH
• SEA CREATURES IN ARIZONA,-COASTLINE
CHANGES
• GIANT FERNS IN N. AMERICA-WARMER
CLIMATE
• WHAT DOES A PALEONTOLOGIST STUDY?
FORMATION OF FOSSILS
http://www.pbs.org/wgbh/evolution/library/04/3/l_043_01.html
• MOST ARE FOUND IN SEDIMENTARY
ROCK-SEDIMENT FORMS WHEN SAND &
SILT FROM WATER SETTLE TO THE
BOTTOM OF A BODY OF WATER
• ANIMALS & PLANTS THAT DIE IN THE
WATER ARE COMPRESSED INTO ROCK BY
PRESSURE FROM THE WATER.
• FOSSIL FORMATION
• http://www.classzone.com/books/earth
_science/terc/content/visualizations/es2
901/es2901page01.cfm?chapter_no=vis
ualization
FORMATION OF FOSSILS
• BONES & TEETH MAY BE PRESERVED ON
LAND BY SHIFTING SAND, MUD OR
VOLCANIC ASH.
• FOOTPRINTS OR SOFT TISSUE CAN BE
PRESERVED IF THEY FILL WITH DUST OR
ASH. THEY ARE THEN COVERED BY
OTHER MATERIALS & HARDEN
FORMATION OF FOSSILS
• PETRIFICATION CAN OCCUR WHEN REMAINS
ARE COVERED WITH WATER
• DISSOLVED MINERALS FROM THE WATER
REPLACE THE DECAYING TISSUES & HARDEN
Petrified wood
GAPS IN THE FOSSIL RECORD
• WHY ARE THERE GAPS?
• CONDITIONS TO FORM FOSSILS NOT PRESENT
• SOME TISSUES ARE TOO SOFT TO FORM
FOSSILS-JELLY FISH, WORMS
• EROSION DESTROYS FOSSILS
• FOSSILS CAN BE BURIED AND NOT FOUND
DO NOW
• 1. Which make better fossils, bone or
footprints?
• 2. Why are there gaps in the fossil record?
• 3. Which is the cast & which one is the mold of
a fossil below?
COMPARISON OF LIVING ORGANISMS
http://www.pbs.org/wgbh/evolution/library/04/2/l_042_02.html
• EMBRYOLOGY
• CHARACTERISICS LOST IN ADULTHOOD
ARE SEEN IN EMBRYOS
• ALL VERTEBRATE EMBRYOS HAVE GILL
POUCHES-NECK FOLDS
• IN FISH DEVELOP INTO GILLS
• IN HUMANS-TRACHEA
• INHERITANCE FROM A FISH-LIKE
ANCESTOR
EMBRYOLOGY
• THE COMMON ANCESTOR OF THESE
ORGANISMS PASSED ON A SINGLE GENETIC
PATTERN OF DEVELOPMENT
• MUTATIONS PASSED ON CHANGES TO THE
ADULT ANIMAL TO CREATE THE DIFFERENCES
IN ADULTHOOD
• TODAYS GENES FOR EMBRYO DEVELOPMENT
HAVE CHANGED LITTLE FROM THE PAST.
CONSERVED GENES
COMPARATIVE ANATOMY
• HOMOLOGOUS STRUCTURES -SIMILAR
STRUCTURES DUE TO A COMMON
ANCESTOR
• FORELIMBS
COMPARATIVE ANATOMY
• ANALOGOUS STRUCTURES -LOOK
SIMILAR BUT ARE USED FOR DIFFERENT
PURPOSES.
•
• NOT FROM A COMMON ANCESTOR
COMPARATIVE ANATOMY
• VESTIGIAL STRUCTURES -INHERITED
FROM AN ANCESTOR BUT UNUSED
An organism with a vestigial feature
probably shares common ancestor with
an organism that has a functional
version of the same feature
COMPARATIVE BIOCHEMISTRY
• GENETIC MATERIAL EXISTS IN EVERY LIFE
FORM
• ORGANISMS W/A RECENT COMMON
ANCESTOR HAVE SIMILAR GENETIC
MAKEUP.
• COMPARISON OF THE GENETIC
SEQUENCES CAN SHOW HOW CLOSELY
RELATED ORGANISMS ARE TO EACH
CLADOGRAM-shows ancestral relationships, timeline
http://www.pbs.org/wgbh/evolution/change/family/
OLD SCHOOL THINKING
NEW SCHOOL
OLD SCHOOL
NEW SCHOOL
Evolution
• The process by which modern
organisms have descended from
ancient organisms
A CHANGE IN A POPULATION OVER TIME
EARLY EXPLANATION FOR EVOLUTIONARY
CHANGE
• TO EXPLAIN FOSSILS, EARLY SCIENTISTS
HYPOTHESIZED THAT CATASTROPHES
OCCURRED
• AFTER EACH CATASTROPHE NEW LIFE WOULD
DEVELOP
• WERE THEY INCORRECT IN THIS LOGIC?
• I. JEAN BAPTIST LAMARCK
1744-1829
Jean Baptiste Lamarck
• A FRENCH NATURALIST, IN CHARGE
OF THE INVERTEBRATES AT THE
HISTORY MUSEUM IN PARIS IN THE
EARLY 1800’S
• One of the first to notice that:
• 1. living things change over time
• 2. organisms are adapted to their
environment
THREE ASSUMPTIONS (INCORRECT) OF
LAMARCK’S THEORY
• 1. ORGANISMS WILL ALWAYS TRY
TO IMPROVE & BECOME ADVANCED
• 2. THE EFFORT TO IMPROVE
CAUSES THE MOST USED
STRUCTURES TO EVOLVE WHILE
OTHER PARTS ARE WASTED AKAPRINCIPLE OF USE AND DISUSE
• 3. ONCE A BODY STRUCTURE IS
MODIFIED BY USE OR DISUSE THE
MODIFICATION IS INHERITED AKA
BUT……
 Lamarck paved the way for Darwin
 First to come up with a theory
 Brought attention to how organisms change
II. AUGUST WEISMANN 1834-1914
AUGUST WEISMANN
• DISPROVED LAMARCK THEORY ON
INHERITED CHARACTERISTICS DUE TO
USE/DISUSE
• CUT OFF THE TAILS OF 22 GENERATIONS
OF MICE
• WHAT WOULD LAMARCK PREDICT?
• ALL MICE WERE BORN WITH TAILS
• AQUIRED CHARACTERISTICS ARE NOT
INHERITABLE
• CHANGES IN INDIVIDUALS DO NOT
Ideas that helped shape Darwin’s
theory of Evolution
1. Principles Of Geology by Lyell
Earth is old
Lots of time is needed for evolution
Geological phenomena could transform
the face of earth over time
If earth could change then life could
change
2. Farmers – Artificial Selection
 Domesticated organisms vary a great deal
 Inheritable variations
 Variation happened or not
 Selectively bred for traits
Artificial Selection
Intervention of humans ensures that only
individuals with the more desirable traits
reproduce
B. THOMAS MALTHUS 1766-1834
• CLERGYMAN WHO WROTE ABOUT
ECONOMICS WHO WROTE ESSAY
“PRINCIPLE OF POPULATION”
• HE SAID “THE HUMAN POPULATION WAS
GROWING SO FAST THAT RESOURCES
THOMAS MALTHUS CONT.
http://www.pbs.org/wgbh/evolution/library/02/5/l_025_01.html
• PLANTS & ANIMALS PRODUCE FAR MORE
OFFSPRING THEN CAN SURVIVE
• HE SUGGESTED THAT LOWER CLASS FAMILY
SIZE BE REGULATED SO THEY CAN NOT
PRODUCE MORE THEN THEY CAN SUPPORT
IV. MAJOR COMPONENTS OF DARWIN’S
NATURAL SELECTION THEORY
• 1844 DARWIN WROTE HIS THEORY ON
EVOLUTION-CALLED IT NATURAL
SELECTION
• THERE ARE 5 POINTS TO HIS THEORY
• 1. VARIATION IN POPULATIONVARIATIONS ARE PASSED ON FROM
PARENT TO OFFSPRING
IV. MAJOR COMPONENTS OF DARWIN’S
NATURAL SELECTION THEORY
• 2. INFLUENCE BY FARMERS/BREEDERS
SOME VARIATIONS ARE FAVORABLE-IF
FAVORABLE IT IMPROVES THE
ORGANISMS ABILITY TO LIVE &
REPRODUCE
DARWIN’S INFLUENCE FROM MALTHUS &
LYELL
• 3. MORE YOUNG ARE PRODUCED THAN
CAN SURVIVE-ONLY A FEW LIVE LONG
ENOUGH TO REPRODUCE
• 4. THOSE THAT SURVIVE & REPRODUCE
HAVE FAVORABLE ?-A LARGER & LARGER
PORTION OF THE NEXT GENERATIONS
WILL INHERIT THESE FAVORABLE
VARIATIONS
• 5. GRADUALISM-OVER A LARGE
AMOUNT OF TIME, SMALL CHANGES
Evolution happens by Natural Selection
How it works:
Variation in a population
More organisms are produced than can
fit in the environment
Struggle to survive – against environment
and each other
Organisms that are well suited to their
environment survive (survival of the
fittest)
Organisms not well suited die
Well suited organisms go on to reproduce
and pass on their well suited traits
(Adaptations)
Overtime this will slowly change a species
V. NATURAL SELECTION IN PEPPERED MOTHS
KETTLEWELL’S OBSERVATION
• BEFORE THE INDUSTRIAL REVOLUTION IN
ENGLAND IN THE LATE 1700’S, THE
FOREST WERE COVERED IN SPOTTED
LICHEN
• SPOTTED MOTHS COULD BLEND INTO
THE BARK COVERED WITH LICHEN
PEPPERED MOTHS
http://bcs.whfreeman.com/thelifewire/content/chp23/2302001.html
• BLACK MOTHS WERE EASY TO SEE AND
WERE EATEN BY PREDATORS
• AFTER THE INDUSTRIAL REVOLUTIONLICHEN STARTED TO TURN BLACK FROM
THE SOOT
• BLACK MOTHS WERE NOW HARDER TO
SEE SO…
• SOON THE SPOTTED MOTH POPULATION
STARTED TO DECLINE & BLACK MOTHS
PEPPERED MOTHS CONTINUED
• 1950’S H.B.D KETTELWELL
HYPOTHESIZED THAT SOMETHING IN
INDUSTRIAL REGIONS CAUSED THE
DARK GRAY MOTH TO BE MORE
SUCCESSFUL THAN LIGHT GRAY MOTHS.
• WHAT WAS IT?
• THE DARK GRAY MOTHS’ ABILITY TO
BLEND INTO THEIR HABITAT AND AVOID
PREDATION.
• DARWIN WOULD CALL THIS?
DO NOW
• 1. Who worked in the invertebrate collection
at a museum in Paris?
• 2. List one of his principles of evolution
• 3. Who wrote a book on economics that
influenced Darwin?
• 4. What did August Weisman do as an
experiment?
• 5. What caused the Peppered Moth’s
population to change?
Species
 A group of similar looking organisms that
breed with one another and produce fertile
offspring in their natural environment
VI. POPULATION GENETICS
• SCIENTISTS STUDY GENETIC TRAITS IN A
POPULATION OVER TIME
• POPULATION OF THE SAME SPECIES CAN BREED
SO THEY SHARE A GENE POOL-COMBINED
GENETIC MAKEUP OF ALL MEMBERS IN A
POPULATION
• REMEMBER-GENES COME IN TWO ALLELES, IN
A GENE POOL EACH ALLELE REPRESENTS A
TRAIT
POPULATION GENETICS
CONTINUED
• THE NUMBER OF TIMES AN ALLELE OCCURS IN
A GENE POOL COMPARED TO THE NUMBER OF
TIMES OTHER ALLELES OCCUR IS CALLED-THE
RELATIVE FREQUENCY OF THAT ALLELE
RELATIVE FREQUENCY AN EXAMPLE
• SUPPOSE HALF A POPULATION OF PLANTS HAS
AN ALLELE OF T FOR TALL HEIGHT, THEN THE
RELATIVE FREQUENCY FOR THE TALL ALLELE IS
50%
• SCIENTISTS LOOK AT ALLELE FREQUENCY
CHANGES IN A POPULATION AS BIOLOGICAL
EVOLUTION
VII. DEVELOPMENT OF NEW
SPECIES
• NICHE-ROLE AN ORGANISM PLAYS IN IT’S
ENVIRONMENT. NO TWO SPECIES CAN
OCCUPY THE SAME NICHE OVER A LONG TIME
PERIOD
• COMPETITION CAUSES ONE TO ADAPT OR
LOOSE OUT
• ONES WITH FAVORABLE TRAITS SURVIVE &
REPRODUCE PASSING ON THEIR TRAITS
THE PROCESS OF SPECIATION
• REPRODUCTIVE ISOLATION-WHEN
SPECIES ARE SEPARATED NEW SPECIES
CAN EVOLVE
• HOW? geographic separation-rivers,
mts., earthquakes
• • CAN RESULT IN DIFFERENT BREEDING
TIMES, BEHAVIOR
• • THE GENE POOL BECOMES CHANGED
OVER TIME DUE TO DIFFERENCES IN
ADAPTATION TO GEOGRAPHIC CHANGE
THE PROCESS OF SPECIATION
• ADAPTIVE RADIATION-ONE SPECIES
GIVES RISE TO NEW ONES
• WHEN ADAPTIVE RADATION OCCURS A
NUMBER OF SPECIES CAN MOVE AWAY
FROM THE ORIGINAL AREA-DIVERGENT
EVOLUTION. EX. LIMBS IN VERTEBRATES
HAVE CHANGED INTO DIFF. SHAPES
• IF SPECIES ARE SIMILAR IN THEIR
APPEARANCE & BEHAVIOR –COVERGENT
EVOLUTION. WINGS OF BATS & BIRDS
GENETIC DRIFT
http://www.wadsworthmedia.com/biology/0495119814_starr/big_picture/ch16_bp.swf
• AN ACCIDENTAL CHANGE IN GENE
FREQUENCY-CATASTROPHES
• FIRE DESTROYS WHITE FLOWERS AND LEAVES
MORE RED-CHANCE
• THE ALLELE FOR RED FLOWERS INCREASES IN
THE GENE POOL
14-3 Genetics and Evolutionary Theory
Darwin did not know anything about
genetics
Genes are the source of variation
Mutations cause variations
Meiosis causes variation as genes are
 given to gametes.
Natural selection works on an
organisms phenotype
Example of Speciation
Darwin’s finches
13 species on Galapagos Islands
Different beaks, different food, different
habitat
How the speciation of finches
occurred
Founding male and female find their
way to – Island A
Separation of populations – a couple
of birds get to – Island B
Changes in the gene pool occur as the
birds adapt to their unique
environments
Reproductive isolation occurs
Sharing the same island – coexistence,
• http://www.britannica.com/EBchecked/topicvideo/66391/16514/Galapagos-finches-haveevolved-many-adaptations-that-allow-them-to
http://www.youtube.com/watch?v=l25MBq8T
77w
The End