Evolution The Unifying Theory of Biology The Unifying Theory of Biology.

EvolutionEvolution

The Unifying Theory

of Biology

The Unifying Theory

of Biology

What’s all the fuss over evolution about?

One side of the debate:I have a strong faith, I can’t

believe in this evolution thing, right?

Other side of the debate:Why are these crazy people out

there trying to bring religion into a scientific event?

What’s all the fuss over evolution about?

One side of the debate:I have a strong faith, I can’t

believe in this evolution thing, right?

Other side of the debate:Why are these crazy people out

there trying to bring religion into a scientific event?

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

• 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

Yeah, we once believed this…

Yeah, we once believed this…

• 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! Is this still what we know?

• 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! Is this still what we know?

Term ReviewTerm Review•Belief•Supernatural •Hypothesis•Theory•Law•Evolution

•Belief•Supernatural •Hypothesis•Theory•Law•Evolution

What is a Scientific Theory?What is a Scientific Theory?• A Scientific Theory is:

– A collection of related natural phenomena– A scientifically accepted principle

•supported by evidence •provides 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 complex and dynamic

• A Scientific Theory is:– A collection of related natural phenomena– A scientifically accepted principle

•supported by evidence •provides 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 complex and dynamic

Scientific Theory (continued)Scientific Theory (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• Quantum Theory• String 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• Quantum Theory• String Theory

Scientific TheoryScientific Theory• 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 Theory?Isn’t Evolution Just a Theory?

History of Evolution(Pre-Charles Darwin’s Idea)

History of Evolution(Pre-Charles Darwin’s Idea)

• Comte de Buffon (late 1700’s)(French Zoologist):

– The debate over how old the earth was led to this man stating that living things had to change over time, 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 (late 1700’s)(French Zoologist):

– The debate over how old the earth was led to this man stating that living things had to change over time, 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

History of Evolution(Pre-Charles Darwin)History of Evolution(Pre-Charles Darwin)

• Lamarck (1744-1829) (French Zoologist)- did not believe life was never changing- developed an inheritance of acquired

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

- his hypothesis was that 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

• Lamarck (1744-1829) (French Zoologist)- did not believe life was never changing- developed an inheritance of acquired

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

- his hypothesis was that 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

History of Evolution(Pre-Charles Darwin’s Idea)

History of Evolution(Pre-Charles Darwin’s Idea)

• Lyell (1777-1875) (English Scientist/Geologist)-developed idea of uniformitarianism that said the earth is much older than 6000 to 40,000 years because the Earth’s surface was operating now just as it had in the

past and changes took great amounts of time (ex. glacial movements, erosion, decomposition)

-used fossils and rock layers and believed gradual changes looked like big gaps in

the fossil records.-believed in continual changes (slower,

progressive change)

• Lyell (1777-1875) (English Scientist/Geologist)-developed idea of uniformitarianism that said the earth is much older than 6000 to 40,000 years because the Earth’s surface was operating now just as it had in the

past and changes took great amounts of time (ex. glacial movements, erosion, decomposition)

-used fossils and rock layers and believed gradual changes looked like big gaps in

the fossil records.-believed in continual changes (slower,

progressive change)

History of Evolution(Pre-Charles Darwin’s Idea)

History of Evolution(Pre-Charles Darwin’s Idea)

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

before (1958) Darwin published his book, On the Origin of Species

– Sent the paper to Darwin for his opinion and when Darwin saw several of their ideas were the same, they presented a joint lecture on the topic the following year

– Does not receive the credit for natural selection due to Darwin’s much more voluminous research and natural history examples

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

before (1958) Darwin published his book, On the Origin of Species

– Sent the paper to Darwin for his opinion and when Darwin saw several of their ideas were the same, they presented a joint lecture on the topic the following year

– Does not receive the credit for natural selection due to Darwin’s much more voluminous research and natural history examples

Charles DarwinCharles Darwin• Born February 12, 1809• Studied medicine (couldn’t handle

blood!)• Five years (1831-1836) on the HMS

Beagle• Discovered many ancient, giant fossils• Named new species• Studied organisms found on a set of

isolated islands…the Galapagos Islands

• Observed finches and tortoises. Paid attention to finch beaks and the various styles of eating methods.

• 22 years later, wrote On the Origin of Species (1859)

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

modification”• Understood inheritance, but not how

genes and DNA play a role in changes to species

• Born February 12, 1809• Studied medicine (couldn’t handle

blood!)• Five years (1831-1836) on the HMS

Beagle• Discovered many ancient, giant fossils• Named new species• Studied organisms found on a set of

isolated islands…the Galapagos Islands

• Observed finches and tortoises. Paid attention to finch beaks and the various styles of eating methods.

• 22 years later, wrote On the Origin of Species (1859)

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

modification”• Understood inheritance, but not how

genes and DNA play a role in changes to species

Evidence since Origins Published

Evidence since Origins Published

• Additional fossils– Transitional species

• Natural experiments– Peppered moth

(England)– Resistance in

Bacteria– Weed/Pest

Resistance• Current Field Work

– Galapagos Finches• Genetics

– DNA Sequencing

• Additional fossils– Transitional species

• Natural experiments– Peppered moth

(England)– Resistance in

Bacteria– Weed/Pest

Resistance• Current Field Work

– Galapagos Finches• Genetics

– DNA Sequencing

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

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

• 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

• 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

Geologic TimeGeologic Time

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

FossilsFossils• 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 are preserved

• 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 are preserved

• Fossils show:– Anatomy

• can reconstruct past organisms

– Relationships between modern and ancestral forms

– Chronological order of organisms

• Simplest forms in oldest strata

• Earliest forms are marine

• Similar organisms succeed one another in time and space

– 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

• Earliest forms are marine

• Similar organisms succeed one another in time and space

– Environmental changes• Major extinctions

– Environmental stability

Fossils show transitionsFossils show transitions

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

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/cell cycle

• Structure– Limb patterns

• Function– Digestive system, 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/cell cycle

• Structure– Limb patterns

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

and apply results to other organisms

• Reproductive processes– Meiosis → gametes

• Developmental processes– Fertilization– Mitosis– Embryonic development

Yes!

So What Are Variations?So What Are Variations?• Differences between

individuals of a species– Caused by mutations

• 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

• Occur in all sexually reproducing organisms

• Differences between individuals of a species– Caused by mutations

• 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

• Occur in all sexually reproducing organisms

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

• Can result in inbreeding and a weakening of a species– Hip dysplasia

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

wouldn’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

• Can result in inbreeding and a weakening of a species– Hip dysplasia

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

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

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

– These characteristics are called adaptations and help organisms survive to reproduce

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

– These characteristics are called adaptations and help organisms survive to reproduce

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:– Variation in traits is the raw material

for change– Constant struggle occurs for existence

among organisms– Some individuals survive and

reproduce– Genetic changes occur in a population– Better adaptation to environment

• Environmental changes affect populations

• Populations affect environment

• Process:– Variation in traits is the raw material

for change– Constant struggle occurs for existence

among organisms– Some individuals survive and

reproduce– Genetic changes occur in a population– Better adaptation to environment

• Environmental changes affect populations

• Populations affect environment

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

What Allows Evolution to Work?

What Allows Evolution to Work?

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)

Why does Evolution Matter Now?

Why does Evolution Matter Now?

• Drug resistance– Bacteria

• Tuberculosis– Viruses

• HIV• Pesticide/Herbicide resistance

– Insect pests• Mosquitoes

– Noxious weeds

• Drug resistance– Bacteria

• Tuberculosis– Viruses

• HIV• Pesticide/Herbicide resistance

– Insect pests• Mosquitoes

– Noxious weeds

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

How Did Humans Evolve?

We are related to monkeys, right??

How Did Humans Evolve?

We are related to monkeys, right??