EvolutionChapters 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

• BUT MORE THEN 99.9% OF ALL SPECIES THAT EVER LIVED ARE NOW EXTINCT

• 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 EXTINCTION-MARINE 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 ISOTOPES-RADIOACTIVE

• 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

• FOSSILS FOUND IN THE ROCK THAT ARE DATED ARE ASSUMED TO BE THE SAME AGE AS THE ROCKS

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 WHAT TYPE OF ROCK?

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 FOSSILShttp://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/es2901/es2901page01.cfm?

chapter_no=visualization

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 ORGANISMShttp://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 OTHER

• HAS CREATED RETHINKING OF SOME ANCESTRY OF ORGANISMS

CLADOGRAM-shows ancestral relationships, timelinehttp://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 AKA-PRINCIPLE OF USE AND DISUSE

• 3. ONCE A BODY STRUCTURE IS MODIFIED BY USE OR DISUSE THE MODIFICATION IS INHERITED AKA INHERITANCE OF AQUIRED CHARACTERISITICS

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 AFFECT

REPROD. CELLS OR OFFSPRING

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 WOULD SOON RUN OUT, PEOPLE WOULD DIE DUE TO DISEASE, WAR & OTHER DISASTERS”

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 POPULATION-VARIATIONS 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 ACCUMULATE & POPULATIONS CHANGE

Evolution happens by Natural Selection

How it works:Variation in a populationMore organisms are produced than can

fit in the environmentStruggle to survive – against

environment and each otherOrganisms that are well suited to their

environment survive (survival of the fittest)

Organisms not well suited dieWell 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 MOTHShttp://bcs.whfreeman.com/thelifewire/content/chp23/2302001.html

• BLACK MOTHS WERE EASY TO SEE AND WERE EATEN BY PREDATORS

• AFTER THE INDUSTRIAL REVOLUTION-LICHEN 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 INCREASED

• THE BLACK MOTHS HAD ADAPTED TO THE ENVIRONMENT

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?• FITNESS!

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?

SpeciesA 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

• • OVER TIME THEY BECOME DIFFERENT SPECIES

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 DRIFThttp://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 variationMutations cause variationsMeiosis causes variation as genes are given to gametes.Natural selection works on an

organisms phenotype

Example of Speciation

Darwin’s finches13 species on Galapagos IslandsDifferent 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 occursSharing the same island – coexistence,

evolution, extinction

• http://www.britannica.com/EBchecked/topic-video/66391/16514/Galapagos-finches-have-evolved-many-adaptations-that-allow-them-to

http://www.youtube.com/watch?v=l25MBq8T77w

The End