EvolutionEvolution

A Unifying Theory of Biology

A Unifying Theory of Biology

I have a strong faith; I can’t believe in this Evolution thing, right?

Wrong!– Religion deals with faith issues and

supernatural forces– Science deals with nature and natural forces

• Evolutionary Theory is science not religion– Science will never prove OR disprove the

existence of God, or any supernatural being. By definition, it can’t!

I have a strong faith; I can’t believe in this Evolution thing, right?

Wrong!– Religion deals with faith issues and

supernatural forces– Science deals with nature and natural forces

• Evolutionary Theory is science not religion– Science will never prove OR disprove the

existence of God, or any supernatural being. By definition, it can’t!

Why is Evolution Controversial Anyway?

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

What is science?What is science?

• Deals exclusively with the natural world and how it operates

• Explains observed events in terms of natural phenomena

• Is an ongoing process of observation about how the world operates

• Collects and organizes information in a systematic way

• Explanations (hypotheses) are “testable” and subject to verification and disproof

• Explanations may be altered or rejected according to available evidence

• Deals exclusively with the natural world and how it operates

• Explains observed events in terms of natural phenomena

• Is an ongoing process of observation about how the world operates

• Collects and organizes information in a systematic way

• Explanations (hypotheses) are “testable” and subject to verification and disproof

• Explanations may be altered or rejected according to available evidence

Yeah, we once believed this…Yeah, we once believed this…• The Earth is stationary• The Universe, including the Sun, revolves around the Earth

– Disproved by Copernicus• The Earth is flat

– Disproved by Galileo• Flies arise spontaneously (spontaneous generation)

– Disproved by Pasteur• Man can’t fly

– Disproved by the Wright Brothers• Atoms can’t be broken down

– Rutherford, Thompson, Chadwick• Space travel is science fiction

– Disproved by the Soviet Union• No personal application for computers…

Why? These fit what was known at the time!

• The Earth is stationary• The Universe, including the Sun, revolves around the Earth

– Disproved by Copernicus• The Earth is flat

– Disproved by Galileo• Flies arise spontaneously (spontaneous generation)

– Disproved by Pasteur• Man can’t fly

– Disproved by the Wright Brothers• Atoms can’t be broken down

– Rutherford, Thompson, Chadwick• Space travel is science fiction

– Disproved by the Soviet Union• No personal application for computers…

Why? These fit what was known at the time!

What is a Scientific Law?What is a Scientific Law?

• A Scientific Law is:– A statement that describes what nature does

under certain conditions– Explains an action or set of actions– Very often mathematical– Like a slingshot!

• Put a rock in the band, the one moving part, pull it back and the rock will fly out at a predictable angle and speed depending on how far back the band is pulled. It will work the same way every time.

• A Scientific Law is:– A statement that describes what nature does

under certain conditions– Explains an action or set of actions– Very often mathematical– Like a slingshot!

• Put a rock in the band, the one moving part, pull it back and the rock will fly out at a predictable angle and speed depending on how far back the band is pulled. It will work the same way every time.

What is a Scientific Theory?What is a Scientific Theory?

• A Scientific theory is:– A synthesis of related natural phenomena– A scientifically accepted principle

• supported by evidence • used to provide an explanation of observed facts • used as a basis for future discussion or investigation

– A system of ideas held as an explanation of a group of facts or phenomena

– An explanation that encompasses general laws, principles, or causes of what is known or unknown

– Very often non-mathematical– Very complex and dynamic

• A Scientific theory is:– A synthesis of related natural phenomena– A scientifically accepted principle

• supported by evidence • used to provide an explanation of observed facts • used as a basis for future discussion or investigation

– A system of ideas held as an explanation of a group of facts or phenomena

– An explanation that encompasses general laws, principles, or causes of what is known or unknown

– Very often non-mathematical– Very complex and dynamic

Scientific Theories Continued….Scientific Theories Continued….

• Scientific theories are verified many times by many researchers.

• Scientific theories are accepted as true by the scientific community as a whole.

• Scientific theories are verified many times by many researchers.

• Scientific theories are accepted as true by the scientific community as a whole.

Some Current Scientific Theories

• Atomic Theory • Big Bang Theory • Cell Theory• Theory of Evolution• Gravity Theory• Germ Theory of Disease• Theory of Relativity• Plate Tectonics Theory• String Theory• Quantum Theory• Unified Field Theory

Some Current Scientific Theories

• Atomic Theory • Big Bang Theory • Cell Theory• Theory of Evolution• Gravity Theory• Germ Theory of Disease• Theory of Relativity• Plate Tectonics Theory• String Theory• Quantum Theory• Unified Field Theory

Scientific Theories are…Scientific Theories are…• Like a car!

– A car is a very complex mixture of parts that function together to get people from one place to another. Parts and systems may be modified from year to year for improvements, but the overall function of the car stays the same.

• Components of a theory can be changed without changing the overall truth of the theory as a whole.

• Like a car!– A car is a very complex mixture of parts that

function together to get people from one place to another. Parts and systems may be modified from year to year for improvements, but the overall function of the car stays the same.

• Components of a theory can be changed without changing the overall truth of the theory as a whole.

Isn’t Evolution Just a Theoryhttp://www.youtube.com/watch?

v=85diEXbJBIk

And where do hypotheses fit in to all this???

And where do hypotheses fit in to all this???

• A hypothesis is:– An educated guess based on observation– An explanation of a single event or

phenomenon based on what is observed but not yet proved

– Supported or refuted by experimentation or continued observation

• A hypothesis is:– An educated guess based on observation– An explanation of a single event or

phenomenon based on what is observed but not yet proved

– Supported or refuted by experimentation or continued observation

The Story in the Rocks…The Story in the Rocks…How do scientists know the Earth’s Age?

• Rocks exist in strata or layers• Strata can be dated according to radioactive decay

– Radioactive emissions are constant and can be measured using the half-life of an element which decays into another element

– Different elements have different lengths of half life varying from 4.5 billion years (U-238) to 5730 years (C-14)

– Radioactive emissions are not affected by external factors

• Amounts of the parent material are compared to amounts of the daughter material

How do scientists know the Earth’s Age? • Rocks exist in strata or layers• Strata can be dated according to radioactive decay

– Radioactive emissions are constant and can be measured using the half-life of an element which decays into another element

– Different elements have different lengths of half life varying from 4.5 billion years (U-238) to 5730 years (C-14)

– Radioactive emissions are not affected by external factors

• Amounts of the parent material are compared to amounts of the daughter material

But There’s More!But There’s More!• Rocks also explain historical Oxygen levels

– Geochemists use isotope geochemistry– Compare rate of isotope accumulation (varies with amount of O2

or CO2 in atmosphere)– Can read:

• Oxygen levels• Air and ocean temperatures• Extent and timing of ice ages

• These changes correspond with changing organism types– Organisms influence Environment– Environment influences Organisms

• Combining this knowledge with fossils and fossil residue (pollen levels) allows recreation of past landscapes!

• The Present is the Key to the Past!– Natural forces now changing the face of the Earth operated in

the past in the same way (Principle of Uniformitarianism)

• Rocks also explain historical Oxygen levels – Geochemists use isotope geochemistry– Compare rate of isotope accumulation (varies with amount of O2

or CO2 in atmosphere)– Can read:

• Oxygen levels• Air and ocean temperatures• Extent and timing of ice ages

• These changes correspond with changing organism types– Organisms influence Environment– Environment influences Organisms

• Combining this knowledge with fossils and fossil residue (pollen levels) allows recreation of past landscapes!

• The Present is the Key to the Past!– Natural forces now changing the face of the Earth operated in

the past in the same way (Principle of Uniformitarianism)

• Geologists divide Earth’s history into Eons, Epochs and Periods

• These divisions correspond to rock strata

• Names vary according to locality

• http://www.enchantedlearning.com/subjects/Geologictime.html

• http://www.pbs.org/wgbh/evolution/change/deeptime/index.html

• Geologists divide Earth’s history into Eons, Epochs and Periods

• These divisions correspond to rock strata

• Names vary according to locality

• http://www.enchantedlearning.com/subjects/Geologictime.html

• http://www.pbs.org/wgbh/evolution/change/deeptime/index.html

Geologic TimeGeologic Time

Fossil RockFossil Rock

• http://www.youtube.com/watch?v=ClJ5lwl_wM0&list=PLvgILFwoRX2luskEUC5XKfzCjmaLnGUse&index=1

• http://www.youtube.com/watch?v=ClJ5lwl_wM0&list=PLvgILFwoRX2luskEUC5XKfzCjmaLnGUse&index=1

FossilsFossils

• Fossils are found in strata (Sedimentary Rock layers)– Similar fossils are found in

similar layers– More complex fossils are

found in ‘younger’ rock closer to the surface

• Fossils include: – Imprints (casts and molds)– bones– Wood– Actual remains

• Fossils are found in strata (Sedimentary Rock layers)– Similar fossils are found in

similar layers– More complex fossils are

found in ‘younger’ rock closer to the surface

• Fossils include: – Imprints (casts and molds)– bones– Wood– Actual remains

• Fossils formed only under specialized conditions– 0.1% of all organisms– Organism quickly covered with sediments– Anaerobic environment– Most often only hard parts survived– Replaced by dissolved minerals– Survive bending and folding by Earth’s processes– One bone in a billion

• Fossils formed only under specialized conditions– 0.1% of all organisms– Organism quickly covered with sediments– Anaerobic environment– Most often only hard parts survived– Replaced by dissolved minerals– Survive bending and folding by Earth’s processes– One bone in a billion

• Fossils show:– Anatomy

• can reconstruct past organisms

– Relationships between modern and ancestral forms

– Chronological order of organisms

• Simplest forms in oldest strata

• Similar organisms succeed one another in time and space

• Earliest forms are marine

– Environmental changes• Major extinctions

– Environmental stability

• Fossils show:– Anatomy

• can reconstruct past organisms

– Relationships between modern and ancestral forms

– Chronological order of organisms

• Simplest forms in oldest strata

• Similar organisms succeed one another in time and space

• Earliest forms are marine

– Environmental changes• Major extinctions

– Environmental stability

Stromatolites in Australia

Fossils show transitionsFossils show transitions

• Whale Evolution– Oldest ancestor, a

wolf-like mammal, moved from the land to the water

– Gradual changes over a long period of time produced our modern whale

• Whale Evolution– Oldest ancestor, a

wolf-like mammal, moved from the land to the water

– Gradual changes over a long period of time produced our modern whale

How Do We Know Evolution Works?

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

Plate Tectonics TheoryPlate Tectonics Theory• Large plates of land

float on molten rock– Convection currents

cause plate movement – Plate movements

result in earthquakes, volcanoes, mountains

• Large plates of land float on molten rock– Convection currents

cause plate movement – Plate movements

result in earthquakes, volcanoes, mountains

– Continents fit together like puzzle pieces

• continental shelves

– Continents fit together like puzzle pieces

• continental shelves

• The uplifting forces of the Earth caused the rock strata to tilt, while erosion exposed the layers which vary in composition and hardness.

• The uplifting forces of the Earth caused the rock strata to tilt, while erosion exposed the layers which vary in composition and hardness.

Mountain Building by uplifting.Mountain Building by uplifting.

• How fossils from the same organism are found on different continents– Glossopteris fern fossils

are found on four continents, including Antarctica

• The Geographical distribution of various species of organisms – Marsupials, found in

Australia and South America are linked through Antarctica

• How fossils from the same organism are found on different continents– Glossopteris fern fossils

are found on four continents, including Antarctica

• The Geographical distribution of various species of organisms – Marsupials, found in

Australia and South America are linked through Antarctica

Plate Tectonics Theory explains:Plate Tectonics Theory explains:

You Mean To Tell Me We’re All Related?You Mean To Tell Me We’re All Related?

Unity of Pattern• Genetic code

– One basic code for all organisms• Cells

– Same cellular organelles and cell cycle

• Structure– Limb patterns

• Function– Digestive system, nerve cells, etc.– Can research various organisms

and apply results to other organisms

• Reproductive processes– Meiosis → gametes

• Developmental processes– Fertilization– Mitosis– Embryonic development

Unity of Pattern• Genetic code

– One basic code for all organisms• Cells

– Same cellular organelles and cell cycle

• Structure– Limb patterns

• Function– Digestive system, nerve cells, etc.– Can research various organisms

and apply results to other organisms

• Reproductive processes– Meiosis → gametes

• Developmental processes– Fertilization– Mitosis– Embryonic development

Yes!

What Went Before (pre-history of Evolution)What Went Before (pre-history of Evolution)

• Comte de Buffon-stated that living things change through time (1700’s)– Therefore, the earth had

to be older than 6000 years (as it was commonly believed to be at this time)

– Did not state these views publicly, but buried them in a 44 volume natural history book series

• Comte de Buffon-stated that living things change through time (1700’s)– Therefore, the earth had

to be older than 6000 years (as it was commonly believed to be at this time)

– Did not state these views publicly, but buried them in a 44 volume natural history book series

• Jean Baptist Lamarck (1744-1829) (French Zoologist)– did not believe life never

changed– developed a hypothesis on

the inheritance of acquired characteristics

• evolution occurs when an organism uses a body part in such a way that it is altered during its lifetime and this change is then inherited by its offspring

– Lengthening necks of Giraffes

– was later proven wrong, but led to idea that all life is connected

• Jean Baptist Lamarck (1744-1829) (French Zoologist)– did not believe life never

changed– developed a hypothesis on

the inheritance of acquired characteristics

• evolution occurs when an organism uses a body part in such a way that it is altered during its lifetime and this change is then inherited by its offspring

– Lengthening necks of Giraffes

– was later proven wrong, but led to idea that all life is connected

More Pre-HistoryMore Pre-History• Evolution as an idea was proposed in early 1800’s• Sir Charles Lyell (Father of modern geology)-popularized

idea of uniformitariansm including that the Earth is much older than originally believed and changes continually

• Erasmus Darwin (Grandpa Darwin) wrote of Evolution before Charles was born

• Patrick Matthew writes about principles of natural selection in Navel Timber and Arboriculture in 1831– No one notices!

• Thomas Malthus suggested related concepts in Essay on the Principle of Populations– Mathematically, food supplies are unable to keep up with

population growth (suggesting competition and unequal survival)

• 1844-Anonymous publication of Vestiges of the Natural History of Creation –controversy abounds!

• Evolution as an idea was proposed in early 1800’s• Sir Charles Lyell (Father of modern geology)-popularized

idea of uniformitariansm including that the Earth is much older than originally believed and changes continually

• Erasmus Darwin (Grandpa Darwin) wrote of Evolution before Charles was born

• Patrick Matthew writes about principles of natural selection in Navel Timber and Arboriculture in 1831– No one notices!

• Thomas Malthus suggested related concepts in Essay on the Principle of Populations– Mathematically, food supplies are unable to keep up with

population growth (suggesting competition and unequal survival)

• 1844-Anonymous publication of Vestiges of the Natural History of Creation –controversy abounds!

Great Men think alike…Great Men think alike…• Alfred Russell Wallace

(1823-1913) (Naturalist)– Wrote a paper about natural

selection in 1858 (one year before Darwin published On the Origin of Species)

– Sent the paper to Darwin for his opinion

– Was part of a joint lecture on the topic along with Darwin the following year

– Did not receive credit for natural selection

• Darwin’s had much more research and natural history examples

• Alfred Russell Wallace (1823-1913) (Naturalist)– Wrote a paper about natural

selection in 1858 (one year before Darwin published On the Origin of Species)

– Sent the paper to Darwin for his opinion

– Was part of a joint lecture on the topic along with Darwin the following year

– Did not receive credit for natural selection

• Darwin’s had much more research and natural history examples

Who was Charles Darwin? Who was Charles Darwin?

• Born Feb 12, 1809• Father-physician, Mother-

daughter of Josiah Wedgwood (Wedgwood pottery)

• Lackluster academic performance

• Studied medicine (couldn’t handle blood!)

• Studied law (too dull!)• Studied and obtained a degree

in divinity (religion!)• Invited to sail on the HMS

Beagle at the age of 22

• Born Feb 12, 1809• Father-physician, Mother-

daughter of Josiah Wedgwood (Wedgwood pottery)

• Lackluster academic performance

• Studied medicine (couldn’t handle blood!)

• Studied law (too dull!)• Studied and obtained a degree

in divinity (religion!)• Invited to sail on the HMS

Beagle at the age of 22

Who Was Charles Darwin?

Sailing the Ocean BlueSailing the Ocean Blue• Five years (1831-1836) on the

HMS Beagle• Discovered many ancient,

giant fossils• Named new species• Geological investigations in the

Andes• Visited a lot of islands

– Species found nowhere else in the world

– Noticed adaptations for exploiting local resources

• Five years (1831-1836) on the HMS Beagle

• Discovered many ancient, giant fossils

• Named new species• Geological investigations in the

Andes• Visited a lot of islands

– Species found nowhere else in the world

– Noticed adaptations for exploiting local resources

Why Islands?Why Islands?Darwin Noticed:• Species that were physically similar occupied adjacent areas• Species were different from mainland species

Islands provide:• Isolation• Variable ecosystems and habitats within each Archipelago• Opportunity for physically similar organisms to:

– Live on same or nearby islands– Look and act in similar ways– Use different resources

• Resources vary according to island– Have different adaptations

• Extreme environmental changes– Organisms unable to escape

Darwin Noticed:• Species that were physically similar occupied adjacent areas• Species were different from mainland species

Islands provide:• Isolation• Variable ecosystems and habitats within each Archipelago• Opportunity for physically similar organisms to:

– Live on same or nearby islands– Look and act in similar ways– Use different resources

• Resources vary according to island– Have different adaptations

• Extreme environmental changes– Organisms unable to escape

Back in England…Back in England…• 1842-Darwin began to formulate his theory

– Darwin failed to note which finch came from which island– Six years required to sort through and order specimens

• 1844-Darwin puts notes and thoughts aside for a while– Fathered 10 children– Studied barnacles for 8 years, variations in pigeons, and earthworms– Pondered arguments for and against his theory

• 1858-Darwin receives a paper from Alfred Russel Wallace– Paper outlines a theory of natural selection very similar to Darwin’s– Prods Darwin into action and publication

• July 1, 1858-Darwin’s and Wallace’s theory unveiled; eventually credit is given to Darwin alone

• 1859-On the Origin of Species published– Biology hasn’t been the same since!

• 1842-Darwin began to formulate his theory– Darwin failed to note which finch came from which island– Six years required to sort through and order specimens

• 1844-Darwin puts notes and thoughts aside for a while– Fathered 10 children– Studied barnacles for 8 years, variations in pigeons, and earthworms– Pondered arguments for and against his theory

• 1858-Darwin receives a paper from Alfred Russel Wallace– Paper outlines a theory of natural selection very similar to Darwin’s– Prods Darwin into action and publication

• July 1, 1858-Darwin’s and Wallace’s theory unveiled; eventually credit is given to Darwin alone

• 1859-On the Origin of Species published– Biology hasn’t been the same since!

Other FactoidsOther Factoids• On the Origin of Species published 22 years

after the voyage of the Beagle.• Darwin struggled with his theory knowing it

would be controversial.• “Survival of the Fittest” coined in 1864 (five

years after Origins published) by Herbert Spencer in Principles of Biology– Never used by Darwin

• “Evolution” not used until 6th edition of On the Origin of Species– Darwin preferred “descent with modification”

• Inheritance understood, but not mechanism– No information about genes and DNA and how they

play a role in changes to species

• On the Origin of Species published 22 years after the voyage of the Beagle.

• Darwin struggled with his theory knowing it would be controversial.

• “Survival of the Fittest” coined in 1864 (five years after Origins published) by Herbert Spencer in Principles of Biology– Never used by Darwin

• “Evolution” not used until 6th edition of On the Origin of Species– Darwin preferred “descent with modification”

• Inheritance understood, but not mechanism– No information about genes and DNA and how they

play a role in changes to species

Evidence since Origins PublishedEvidence since Origins Published

• Additional fossils– Transitional species

• Natural experiments– Peppered moth (Biston

betularia) in England– Resistance in Bacteria– Weed/Pest Resistance

• Current Field Work– Galapagos Finches

• Genetics• DNA Sequencing

– Shows degree of relatedness

• Additional fossils– Transitional species

• Natural experiments– Peppered moth (Biston

betularia) in England– Resistance in Bacteria– Weed/Pest Resistance

• Current Field Work– Galapagos Finches

• Genetics• DNA Sequencing

– Shows degree of relatedness

The skulls of two pakicetid whales (Ichthyolestes on the left, Pakicetus on the right), flank the skull of a modern coyote.

Current Evolutionary StudiesCurrent Evolutionary Studies• Peter and Rosemary Grant

– Galapagos finches - Several decades• Measurable changes in beak size according to environmental

changes– http://www.pbs.org/wgbh/evolution/library/01/6/pdf/l_016_01.pdf

• William Rice and George Salt– Drosophila melanogaster – 35 generations

• Achieved two distinct fly populations adapted to different habitat conditions

• Richard Lenski– E. coli bacteria – Studied changes over 20,000 generations

All demonstrate that evolutionary change is very slow!– Thousands of generations required for speciation and

divergence into two species.

• Peter and Rosemary Grant– Galapagos finches - Several decades

• Measurable changes in beak size according to environmental changes

– http://www.pbs.org/wgbh/evolution/library/01/6/pdf/l_016_01.pdf

• William Rice and George Salt– Drosophila melanogaster – 35 generations

• Achieved two distinct fly populations adapted to different habitat conditions

• Richard Lenski– E. coli bacteria – Studied changes over 20,000 generations

All demonstrate that evolutionary change is very slow!– Thousands of generations required for speciation and

divergence into two species.

Top Common Misconceptions of Evolution

Top Common Misconceptions of Evolution

• There hasn’t been enough time for all this to happen– False! Modern geology has shown the earth to be ancient in

origin.

• Only microorganisms evolve– False! Many recent studies have shown macroorganisms

changing in response to the environment; that is, evolving!

• Man evolved from monkeys/apes– False! We share a common ancestor with characteristics of both

apes and humans. It was neither an ape or a human

• There hasn’t been enough time for all this to happen– False! Modern geology has shown the earth to be ancient in

origin.

• Only microorganisms evolve– False! Many recent studies have shown macroorganisms

changing in response to the environment; that is, evolving!

• Man evolved from monkeys/apes– False! We share a common ancestor with characteristics of both

apes and humans. It was neither an ape or a human

Theories that set the stageTheories that set the stage

• Catastrophism—natural disasters happen often during Earth’s history which shape landforms and causes species to become extinct (Cuvier)

• Gradualism—slow changes over long periods of time (Hutton)

• Uniformitarianism—geological processes that shape the Earth are uniform though time.(Lyell)

• Catastrophism—natural disasters happen often during Earth’s history which shape landforms and causes species to become extinct (Cuvier)

• Gradualism—slow changes over long periods of time (Hutton)

• Uniformitarianism—geological processes that shape the Earth are uniform though time.(Lyell)

What Allows Evolution to Work?What Allows Evolution to Work?• Organisms make up Species

– Organisms that can mate and produce fertile offspring

– Make up populations that live in different areas

• Mountain Lion (Puma, Cougar, Catamount)

• Florida Panther– tail crook, whorl of hair,

and white flecking – Considered a subspecies

– Individuals have variations

• Organisms make up Species– Organisms that can mate and

produce fertile offspring– Make up populations that live

in different areas• Mountain Lion (Puma,

Cougar, Catamount)• Florida Panther

– tail crook, whorl of hair, and white flecking

– Considered a subspecies

– Individuals have variations

Florida Panther(Puma concolor coryi)

Mountain Lion(Puma concolor)

But Wait! How do you explain Dogs?

But Wait! How do you explain Dogs?

• Dogs are the same species despite looking very different

• Variation has created reproductive isolation between the biggest and smallest dogs

• Intermediate forms bridge the gap

• Looks can be misleading!– DNA is mechanism– Variation is the key

• Dogs are the same species despite looking very different

• Variation has created reproductive isolation between the biggest and smallest dogs

• Intermediate forms bridge the gap

• Looks can be misleading!– DNA is mechanism– Variation is the key

So What Are Variations?So What Are Variations?

• Differences between individuals of a species– Caused by mutations– Can lead to speciation-

the formation of new species

• Occur in all sexually reproducing organisms

• Small or major

• Differences between individuals of a species– Caused by mutations– Can lead to speciation-

the formation of new species

• Occur in all sexually reproducing organisms

• Small or major

• Provide a survival advantage for an individual– Allows beneficial

genes to be passed on to offspring

• Must be passed on for change to occur in a population

• Provide a survival advantage for an individual– Allows beneficial

genes to be passed on to offspring

• Must be passed on for change to occur in a population

But…Where do they come from?But…Where do they come from?Remember: Variations must be passed on

for changes to occur in a population.

• Two major sources– Mutations

• Changes in DNA sequence• Beneficial, harmful, neutral• 1 per 1 billion per cell• Not always detectable

– Recessive– Introns

• Create new genetic material– Add to the gene pool (sum of all alleles in a population)

Remember: Variations must be passed on for changes to occur in a population.

• Two major sources– Mutations

• Changes in DNA sequence• Beneficial, harmful, neutral• 1 per 1 billion per cell• Not always detectable

– Recessive– Introns

• Create new genetic material– Add to the gene pool (sum of all alleles in a population)

You Mean To Tell Me We’re All Related?You Mean To Tell Me We’re All Related?

Unity of Pattern• Genetic code

– One basic code for all organisms• Cells

– Same cellular organelles and cell cycle

• Structure– Limb patterns

• Function– Digestive system, nerve cells, etc.– Can research various organisms

and apply results to other organisms

• Reproductive processes– Meiosis → gametes

• Developmental processes– Fertilization– Mitosis– Embryonic development

Unity of Pattern• Genetic code

– One basic code for all organisms• Cells

– Same cellular organelles and cell cycle

• Structure– Limb patterns

• Function– Digestive system, nerve cells, etc.– Can research various organisms

and apply results to other organisms

• Reproductive processes– Meiosis → gametes

• Developmental processes– Fertilization– Mitosis– Embryonic development

Yes!

Second Source:– Genetic Recombination

• Diploidy (adults have two copies of chromosomes)

– Shuffling of chromosomes

– Only 4 alleles produces 64 trillion combinations

• Crossing over– Within a gene sequence– Unequal redistribution of

genetic material

Second Source:– Genetic Recombination

• Diploidy (adults have two copies of chromosomes)

– Shuffling of chromosomes

– Only 4 alleles produces 64 trillion combinations

• Crossing over– Within a gene sequence– Unequal redistribution of

genetic material

So What is the Theory of Evolution Really About?

So What is the Theory of Evolution Really About?

Two main ideas:• Historical evolution of all

species– Common ancestor

• Natural Selection as the mechanism for evolution– characteristics that help an individual survive and

reproduce will be passed on to offspring

– Advantageous characteristics will replace less advantageous characteristics in a population

– Characteristics are called adaptations

Two main ideas:• Historical evolution of all

species– Common ancestor

• Natural Selection as the mechanism for evolution– characteristics that help an individual survive and

reproduce will be passed on to offspring

– Advantageous characteristics will replace less advantageous characteristics in a population

– Characteristics are called adaptations

Natural Selection explains byNatural Selection explains by

• Variation

• Adaptation

• Overpopulation

• Reproductive Isolation

• Descent with modifications

• Variation

• Adaptation

• Overpopulation

• Reproductive Isolation

• Descent with modifications

Artificial SelectionArtificial Selection• Breeding for specific, desirable

traits– Domesticated animals

• Dogs, cats• Cattle, sheep, pigs

– Domesticated plants• Corn, wheat

• Takes a long time– Hundreds of generations– Only works with certain plants

and animals• Can result in inbreeding and a

weakening of a species– Hip dysplasia

Inspired Darwin to think of Natural Selection– If people could do this,

couldn’t it happen on it’s own in nature?

• Breeding for specific, desirable traits– Domesticated animals

• Dogs, cats• Cattle, sheep, pigs

– Domesticated plants• Corn, wheat

• Takes a long time– Hundreds of generations– Only works with certain plants

and animals• Can result in inbreeding and a

weakening of a species– Hip dysplasia

Inspired Darwin to think of Natural Selection– If people could do this,

couldn’t it happen on it’s own in nature?

What are adaptations?What are adaptations?• Anything that helps

an organism survive and reproduce– Polar bear

• Hollow Hair

• Wooly Undercoat

• Feet

• Sense of smell

• Color

• Black Skin

• Anything that helps an organism survive and reproduce– Polar bear

• Hollow Hair

• Wooly Undercoat

• Feet

• Sense of smell

• Color

• Black Skin

– Cactus• Thorns

• Wax coating

• Roots

– Cactus• Thorns

• Wax coating

• Roots

How does Natural Selection Work?How does Natural Selection Work?• Process:

– Variations provide the raw material for change.• Genetic mutations expressed in phenotype

– Constant struggle for existence occurs among organisms.• Competition for resources

– Certain individuals survive and reproduce.• Survival of the fittest

– Genetic changes occur in a population• Change in the gene pool

– Organisms are better adapted to the environment.• Better able to compete

• Environmental changes affect populations– Natural and man-made disasters– Climate change

• Populations affect environment– overgrazing

• Process:– Variations provide the raw material for change.

• Genetic mutations expressed in phenotype– Constant struggle for existence occurs among organisms.

• Competition for resources– Certain individuals survive and reproduce.

• Survival of the fittest– Genetic changes occur in a population

• Change in the gene pool– Organisms are better adapted to the environment.

• Better able to compete• Environmental changes affect populations

– Natural and man-made disasters– Climate change

• Populations affect environment– overgrazing

How does Evolution Really Work?

What Else Allows Evolution To Work?

What Else Allows Evolution To Work?

• Reproductive Isolation– Maintains distinctness– Prevents interbreeding – Allows formation of

new species (speciation)

• Reproductive Isolation– Maintains distinctness– Prevents interbreeding – Allows formation of

new species (speciation)

Ways to Achieve Reproductive Isolation

Ways to Achieve Reproductive Isolation

• Prevent Mating – Geographical

• Live in different areas (Physical and Ecological Barriers)

• Formation of subspecies • Leads to speciation

– Behavioral• Different mating rituals

– Tree and Meadow Pipit– Physical

• Size difference

• Chromosome Incompatibility– Death of Offspring

• Leopard and Bullfrog→Embryos fail to develop

– Sterile Offspring• Horse + Donkey → Mule

• Prevent Mating – Geographical

• Live in different areas (Physical and Ecological Barriers)

• Formation of subspecies • Leads to speciation

– Behavioral• Different mating rituals

– Tree and Meadow Pipit– Physical

• Size difference

• Chromosome Incompatibility– Death of Offspring

• Leopard and Bullfrog→Embryos fail to develop

– Sterile Offspring• Horse + Donkey → Mule

Other Factors…Other Factors…

• More individuals are born than can survive

• Excess population growth drives competitive struggle for resources– More successful=more

surviving offspring– Less successful=fewer

surviving offspring

• More individuals are born than can survive

• Excess population growth drives competitive struggle for resources– More successful=more

surviving offspring– Less successful=fewer

surviving offspring

Mechanisms affecting PopulationsMechanisms affecting Populations

• Allele frequencies generally stay stable in a population– Population is in equilibrium

• Frequency can be changed– Mutation

• Expressed in phenotype

– Artificial or natural selection• Strong selection pressure=faster changes• Weak selection pressure=slow change

• Allele frequencies generally stay stable in a population– Population is in equilibrium

• Frequency can be changed– Mutation

• Expressed in phenotype

– Artificial or natural selection• Strong selection pressure=faster changes• Weak selection pressure=slow change

• Changes in allele frequency cont.– Migration– Random Change

• Genetic Drift– Affects small populations most (small gene pool)

• Natural Forces

– Nonrandom mating of individuals• Sexual Selection

• Changes can lead to Reproductive Isolation– Speciation

• Changes in allele frequency cont.– Migration– Random Change

• Genetic Drift– Affects small populations most (small gene pool)

• Natural Forces

– Nonrandom mating of individuals• Sexual Selection

• Changes can lead to Reproductive Isolation– Speciation

SpeciationSpeciation• Development of a new

species based on a natural selection and variations– Subspecies occur first

• Occurs via adaptive radiation– offspring of a species

disperses– Adaptation to the new area

occurs over time– New traits are bred into

future generations– Process continues

• Development of a new species based on a natural selection and variations– Subspecies occur first

• Occurs via adaptive radiation– offspring of a species

disperses– Adaptation to the new area

occurs over time– New traits are bred into

future generations– Process continues

Mountain Lion

(Puma concolor)

Florida Panther(Puma concolor coryi)

Evolutionary Patterns:Parallel Evolution

Evolutionary Patterns:Parallel Evolution

• After divergence, closely related organisms evolve in the same direction

• live in different places with similar environmental selection pressure– Large flightless birds

• Emu• Rhea• Ostrich

• After divergence, closely related organisms evolve in the same direction

• live in different places with similar environmental selection pressure– Large flightless birds

• Emu• Rhea• Ostrich

Evolutionary Patterns:Convergent Evolution

Evolutionary Patterns:Convergent Evolution

• Similar features evolve independently in unrelated organisms living in similar habitats

• similar environmental selection pressure– Dolphins and sharks– Bats and birds

• Similar features evolve independently in unrelated organisms living in similar habitats

• similar environmental selection pressure– Dolphins and sharks– Bats and birds

Evolutionary Patterns:Co-evolution

Evolutionary Patterns:Co-evolution

• Two unrelated groups of organisms evolve adaptations to each other – Depend on each other

for survival• Yucca and Yucca Moth• Ants and Acacia trees

• Two unrelated groups of organisms evolve adaptations to each other – Depend on each other

for survival• Yucca and Yucca Moth• Ants and Acacia trees

Vestigial StructuresVestigial Structures

• Remnants of organs or structures that had a function in an early ancestor

• Remnants of organs or structures that had a function in an early ancestor

Vestigial StructuresVestigial Structures• Left over body parts with

no current function– Snakes

• pelvis

– Humans– Flightless beetles

• wings

– Whales• Pelvis and back legs

• Show common ancestry

• Left over body parts with no current function– Snakes

• pelvis

– Humans– Flightless beetles

• wings

– Whales• Pelvis and back legs

• Show common ancestry

Homologous StructuresHomologous Structures

• that are similar in structure but appear in different organisms and have different functions

• that are similar in structure but appear in different organisms and have different functions

Analogous StructuresAnalogous Structures

• Structures that perform a similar function but are not similar in origin

• Structures that perform a similar function but are not similar in origin

Fossils provide a record of evolutionFossils provide a record of evolution

• Paleontology—study of fossils or extinct organisms

• Molecular & Genetic evidence supports fossil & anatomical evidence

• Paleontology—study of fossils or extinct organisms

• Molecular & Genetic evidence supports fossil & anatomical evidence

• DNA sequence analysis

• Pseudogenes (sequences of DNA nucleotides)

• DNA sequence analysis

• Pseudogenes (sequences of DNA nucleotides)

• Homeobox genes (controls development of specific structures)

• Protein Comparisons

• Homeobox genes (controls development of specific structures)

• Protein Comparisons

Why does Evolution Matter Now?Why does Evolution Matter Now?

• Drug resistance– Bacteria

• Tuberculosis

– Viruses• HIV

• Pesticide/Herbicide resistance– Insect pests

• Mosquitoes

– Noxious weeds• Sericea Lespedeza

• Drug resistance– Bacteria

• Tuberculosis

– Viruses• HIV

• Pesticide/Herbicide resistance– Insect pests

• Mosquitoes

– Noxious weeds• Sericea Lespedeza

Why Does Evolution Matter Now?

What About Us? What About Us?

• Discovered by Dr. Richard Leakey and Mary Leakey

• Africa• Most complete fossil

skeleton found• bipedal• Australopithecus

afarenisis

• Discovered by Dr. Richard Leakey and Mary Leakey

• Africa• Most complete fossil

skeleton found• bipedal• Australopithecus

afarenisis

Dr Leakey

Reproduction of Lucy’s completed skull

Lucy

What else?What else?

• Similarities between primates– Eyes directed forward

• View 3-dimentionally• Depth perception

– Opposable thumb– Large brain– Single offspring

• Extended maternal care• Teaching of offspring

– Social groupings– DNA

• Chimpanzees and humans share 98.5% of their DNA

• Similarities between primates– Eyes directed forward

• View 3-dimentionally• Depth perception

– Opposable thumb– Large brain– Single offspring

• Extended maternal care• Teaching of offspring

– Social groupings– DNA

• Chimpanzees and humans share 98.5% of their DNA

•A clade is a group of organisms that include all the decedents of a common ancestor and that ancestor.

4) 2.5 mya: Some hominids made tools by chipping stones to form a cutting edge. There were perhaps four or more species of hominid living in Africa.

7) 100,000 years ago: Human brains reached more or less the current range of sizes. Early Homo sapiens lived in Africa. At the same time, Homo neanderthalensis and Homo erectus lived in other parts of the Old World.

9) 25,000 years ago: Other Homo species had gone extinct, leaving only modern humans, Homo sapiens, spread throughout the Old World.

1. Before 5 mya: In Africa, our ancestral lineage and the chimpanzee lineage split.

6) 1.5 mya: Hand axes were used. Also, hominids had spread out of Africa and into much of Asia and Europe. These hominids included the ancestors of Neanderthals (Homo neanderthalensis) in Europe and Homo erectus in Asia.

8) 50,000 years ago: Human cultures produced cave paintings and body adornment, and constructed elaborate burials. Also, some groups of modern humans extended their range beyond Africa.

2. Before 4 mya: The hominid Australopithecus anamensis walked around what is now Kenya on its hind legs.

5) 2 mya: The first members of the Homo clade, with their relatively large brains, lived in Africa.

3. 3 mya: Australopithecus afarensis (“Lucy”) lived in Africa.

Modern Human Ancestry

Did Humans Evolve?

• Classification comparison:– more similar categories show closer relationship

• Classification comparison:– more similar categories show closer relationship

Humans Chimpanzee Mouse Maize (corn)

Kingdom: Animalia Animalia Animalia Plantae

Phylum: Chordata Chordata Chordata Angiospermae

Subphylum: Vertebrata Vertebrata Vertebrata ***

Class: Mammalia Mammalia Mammalia Monocotyledons

Order: Primates Primates Rodentia Poales

Family: Hominidae Pongidae Muridae Poaceae

Genus: Homo Pan Mus Zea

Species: Homo sapiens Pan troglodytes Mus musculus Zea mays

% Cytochrome C Shared

100% 91.3% 66.7%Cytochrome C is a protein sequence found in almost all living organisms.

SummarySummary

• Individuals have variations• Variations allow for differential survival in

response to the environment• Beneficial variations are passed on to offspring• Genetic changes occur in a population over time• Speciation

• Occurs in all populations • Takes a very long time

• Individuals have variations• Variations allow for differential survival in

response to the environment• Beneficial variations are passed on to offspring• Genetic changes occur in a population over time• Speciation

• Occurs in all populations • Takes a very long time

To learn more…To learn more…• www.pbs.org/wgbh/evolution• http://www.talkorigins.org/• http://www.madsci.org/FAQs/evolve.html• http://www.actionbioscience.org/evolution/index.html• http://www.evolutionhappens.net/• http://www.ucmp.berkeley.edu/historyoflife/

histoflife.html• http://mcb.harvard.edu/BioLinks/Evolution.html• http://www.bbc.co.uk/education/darwin/index.shtml• http://www.becominghuman.org• http://evolution.berkeley.edu//evosite/evo101/

index.shtml

• www.pbs.org/wgbh/evolution• http://www.talkorigins.org/• http://www.madsci.org/FAQs/evolve.html• http://www.actionbioscience.org/evolution/index.html• http://www.evolutionhappens.net/• http://www.ucmp.berkeley.edu/historyoflife/

histoflife.html• http://mcb.harvard.edu/BioLinks/Evolution.html• http://www.bbc.co.uk/education/darwin/index.shtml• http://www.becominghuman.org• http://evolution.berkeley.edu//evosite/evo101/

index.shtml