Objectives:

Describe natural selection

Catalyst: What is a half life?

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GEOLOGIC HISTORY OF THE EARTH

HADEAN TIME

• 4.5 to 3.8 billion years ago

• During Hadean time, the Solar System was forming, probably within a large cloud of gas and dust around the sun

Archaean3.8 to 2.5 billion years ago

• Methane, ammonia, and other gases which would be toxic to most life on our planet today filled atmosphere.

• Earth's crust cooled enough that rocks and continental plates began to form.

Proterozoic Era2.5 billion to 543 million years ago

• stable continents first appeared

• Oxygen begins to build up in the atmosphere.

• Birth of eukaryotic cells

PALEOZIC543 to 248 Million Years Ago

• At its beginning, multi-celled animals underwent a dramatic Explosion in diversity

• At the other end of the Paleozoic, the largest mass extinction in history wiped out approximately 90% of all marine animal species.

Introduction to the Mesozoic Era248 to 65 Million Years Ago

• Dinosaurs and such

• Mass Extinction again!

Introduction to the Cenozoic65 Million Years to the Present

• Finally Humans are coming around

• HUMANS ARE BABIES IN GEOLOGIC TIME!!!

According to scientists, the

earth is about 4.5 billion years old.

James Ussher, using biblical genealogy,

calculated that creation began on

Sunday, October 23, 4004 BC

Annals of the World

Thus, according to Flat Earth

creationists, the earth is about 6

thousand years old.

Evidence for

Evolution

THE AGE OF THE EARTH

2 ways to date the earth:

• Relative Dating—lower levels of rock are older than higher levels (not exact)

• Absolute Dating—the actual age of a sample using carbon dating

RELATIVE DATING

RELATIVE DATING

RADIOMETRIC DATING

EVIDENCE FOR

EVOLUTION FROM THE

PAST

The fossil record shows that changes in

organisms followed changes on earth.

Example:Shark teeth in Arizona

PLACES TO FIND FOSSILS:

• Ice• Tar Pits / quicksand / bogs• Amber / Sap• Sedimentary Rock—sediments fall

on the living material and turn it to rock

Fossils in Amber

Fossils are an incomplete record of evolution because:

• Fossil record is incomplete. Some organisms leave fossils, but most do not

• Quality is variable. Some are perfect, some are not…missing details

Present-Day Evidence Present-Day Evidence for Evolutionfor Evolution

• DNA SimilarityDNA Similarity• Homologous StructuresHomologous Structures• Vestigial StructuresVestigial Structures• EmbryosEmbryos

Species Percent DNA Binding

Human 100

Chimpanzee 98

Gibbon 94

Rhesus monkey 88

Tarsier 65

Lemur 47

Mouse 21

Chicken 10

DNA Similarity: Species that are more alike share more

similar DNA structures

Homologous StructuresEvidence for Evolution

HOMOLOGOUS STRUCTURES

parts in different organisms that develop from the same

anscestoral body part

HOMOLOGOUS STRUCTURES

Vestigial StructuresEvidence for Evolution

VESTIGIAL STRUCTURES

structures that have little or no purpose in the present,

but did in the past

Examples of Vestigial Structures

• Human appendix

• Tonsils

• Small vertebrae in humans

• Leg bones in snakes

EMBRYOSEvidence for Evolution

EMBRYOorganisms in the early stages of development.

Embryo Similarity• What do you

notice about the first row?

• What happens as you move down each column?

Requirements:

More individuals are born each generation than can survive: the "Struggle for Existence"

Organisms in population have different traits (Giraffe's necks)

And some traits give animals greater fitnessExample:Giraffes with longer

necks get better food, have more babies(greater fitness)

Longer necks give birth to longer necks(trait is passed on in genes)

Results:

Over time the favored trait dominates

Example:average neck length increases

PEPPERED MOTHS:

NATURAL SELECTION IN ACTION!

LOOK AT THE MOTHS BELOW AND PREDICT THE

TYPE OF HABITAT THEY WOULD LIVE IN

PEPPER MOTHSpre-industrialization

Which moth would be more fit? WHY???

PEPPER MOTHSpost-industrialization

Which moth would be more fit? WHY???

On what does natural selection operate?

PHENOTYPIC VARIATION

What is the cause of Phenotypic Variation?

GENETIC MUTATIONS and CROSSING OVER

Principles of Populations

• Thomas Malthus - populations increase faster than environment can handle

• Lyell – earth is really old

Relating geological evolution to biological evolution:

• Lamarck was the first to propose a mechanism that related environment to biological changes (1809)– Use and Disuse– You can get a longer neck by using those

muscles and wishing for it– Inheritance of Acquired Characteristics

Lamark believed:• Organisms have a desire to change (if

a giraffe wants a long neck, he can try hard and get one)

• Use and disuse mattered • Physical traits (i.e. neck length or

strength) could be passed to offspring

CHARLES DARWIN• From Britain• Sailed around the world on a

ship called the HMS Beagle• Published On the Origin of

Species by Natural Selection, 30 years after he got back.

• Theory of NATURAL SELECTION

THE DEVELOPMENT

OF NEW SPECIES

POPULATIONa collection of

individuals of the same species in a given area

that can breed with one another

NICHEthe combination of an

organism’s habitat and its job or role in

that habitat(making a living)

Niche Examples

• Rat -eating garbage can - cleaner

• Hedgehog -eating stuff in gardens

NO TWO SPECIES CAN OCCUPY THE SAME NICHE FOR

VERY LONG!!!

CONVERGENT EVOLUTION

creation of organisms that are similar in appearance and

behavior(bats, birds, butterflies)

DIVERGENT EVOLUTION

(aka Adaptive Radiation)different species diverge

from a common ancestor / become less alike

Stabilizing

• Best to be in the middle

Disruptive

• Best to be on one extreme or other extreme

Directional

• Best to be on one end

Newspaper Lab

EVOLUTION BY NATURAL SELECTION

Two Major Components of Evolution

heritable variation (random)» mutation» recombination (sex, etc.)

natural selection (nonrandom)

Principles of Populations

• Thomas Malthus (1798) published that populations increase faster than environment can handle

• Capacity to over-reproduce is seen in all species

• Eventually populations stop increasing in size and reach a steady state (carrying capacity)

Geology• Hutton ( 1795) theory of gradualism that

major changes are the result of slow small changes

• Lyell (1830) geological changes throughout time have been subjected to the same forces

• Conclusions:– If geological changes are slow earth is older

than 6,000 years old– the slow changes can build and result in

profound environmental changes over time

Relating geological evolution to biological evolution:

• Theories of biological evolution begin in the late eighteenth century

• Lamarck was the first to propose a mechanism that related environment to biological changes (1809)– Use and Disuse– Inheritance of Acquired Characteristics

Mechanism : Natural Selection

• Fact 1: Over-reproduction occurs in nature

• Fact 2: Populations do not increase exponentially

• Fact 3: There are limited natural resources (food, shelter)

• These facts are seen in Malthus’ works on populations

• Inference 1:• struggle for survival ensues• Fact 4: Variation exists in populations• Fact 5: Much of the variation is heritable• Fact 4 was physically observed. Darwin’s

weakness was the 5th fact• Inference 2:• Organisms with the best variations survive the

struggle for life• Inference 3:• Unequal survival of organisms with different

variations leads to favorable variations accumulating over time

Key Concepts

• What is the raw material necessary for the mechanism of Natural Selection?

• Heritable variations

• What is the smallest unit of evolution?

• Populations

• Darwin incorporated Lyell’s gradualism into biological evolution combined with Malthus’ observations regarding populations

Examples of Natural Selection

• Grants on the island of Daphne Major

• observed shifts in the frequency of beak sizes over short periods of time

• Peppered moths

• Antibiotic resistance in bacteria

• How do the genetic variations arise in nature?

Evidence for Evolution• Artificial selection

• Island biogeography

• Fossil record

• Taxonomy

• Comparative Anatomy

• Vestigial Structures

• Comparative Embryology

• Molecular Biology

Eye sockets in blind salamanders

2 Early Views of Evolution

•Lamark (wrong)

•Darwin (right)

Lamark believed:• Organisms have a desire to change (if

a giraffe wants a long neck, he can try hard and get one)

• Use and disuse mattered • Physical traits (i.e. neck length or

strength) could be passed to offspring

CHARLES DARWIN• From Britain

• Sailed around the world on a ship called the HMS Beagle

• Published On the Origin of Species by Natural Selection, 30 years after he got back.

3 MAJOR FACTORS INFLUENCING DARWIN• The age of the earth (Lyell)• Population controls (Malthus)• Breeding programs-aka Artificial Selection (Farmers)

ARTIFICIAL SELECTION

Humans make sure that only individuals with more desirable traits

produce offspring

Journal Topic #5Pretend that you are Charles Darwin living in Franklin.

Could you propose the theory of evolution here, today, for the 1st time? Explain why or

why not?

NATURAL SELECTION

The process in nature where the most fit

organisms produce more offspring

SURVIVAL OF THE FITTEST

Individuals whose traits are well suited to the environment survive and reproduce. Those

who aren’t suited, die!!! (or leave fewer offspring)

GENE POOLa common group of genes shared by a

population

RELATIVE FREQUENCY

the # of times an allele occurs in a gene pool compared with other

alleles for the same gene

EVOLUTIONany change in the

relative frequencies of alleles in the gene pool

of a population

Journal Topic #6What are some of the

differences you observe in the fish? Why do some look

different than others? How might these differences relate

to evolution?

HUMAN EVOLUTION

“Time Marches On”

Primates

PRIMATESanimals with five

flexible fingers with an opposable thumb

(include monkeys, apes, and humans)

Facts on Primates• Have binocular and color

vision

• Evolved about 35 million years ago

Taxonomic Chart of Human Evolution

THE GREAT APES

Chimpanzee Bonobo Gorilla Orangutan

Man’s Closest Living Relatives

Human DNA and chimp DNA

is 98.4% similar!!!

Genetic Relationships

Evolutionary Origins of Humans

HOMINIDShumans and their

closest fossil relatives

Skulls are evidence for human evolution

A bonabo with bipedal locomotion.

“Lucy”• The oldest hominid (3 myo)

• Discovered by Johanson in 1974 in Ethiopia

• About 3.5 ft tall / 62 lbs

• Walked upright

• Evidence that hominids walked upright before they evolved larger brains

The First Humans

The genus Homo evolved in Africa about 2 million years ago

Journal Topic #8

What are the adaptations of modern humans? Do you

believe that humans could be the product of evolution by

natural selection?

Journal Topic #9Should evolution be taught in schools?

Explain why or why not. Please be

detailed.

Why is evolutionary Biology Why is evolutionary Biology Important?Important?

Health SciencesHealth Sciences – infectious – infectious diseases, resistance to antibiotics; diseases, resistance to antibiotics; human immunodeficiency virus (HIV) human immunodeficiency virus (HIV) - origin and spread; Relation between - origin and spread; Relation between disease and disease vectors (e.g., disease and disease vectors (e.g., malaria and mosquitoes)malaria and mosquitoes)

Why is evolutionary Biology Why is evolutionary Biology Important?Important?

Agriculture – Agriculture – varieties of crops and varieties of crops and domesticated animals have domesticated animals have traditionally been developed by traditionally been developed by selective breeding or artificial selective breeding or artificial selection – which is simply evolution selection – which is simply evolution directed by humans; pesticide directed by humans; pesticide resistance presents an enormous resistance presents an enormous challenge for humans.challenge for humans.

Why is Evolutionary Biology Why is Evolutionary Biology Important?Important?

Natural Products – Natural Products – penicillin (from penicillin (from a fungus), aspirin (salicylic acid, from a fungus), aspirin (salicylic acid, from willow trees), and quinine (a willow trees), and quinine (a compound from cinchona tree, used compound from cinchona tree, used to treat malaria) are a few of the to treat malaria) are a few of the natural products used in medicine.natural products used in medicine.

Today, biologists are using the Today, biologists are using the fundamentals of evolutionary biology fundamentals of evolutionary biology to search for other natural products to search for other natural products or to advance biotechnology (e.g., or to advance biotechnology (e.g., PCR)PCR)

Why is Evolutionary Biology Why is Evolutionary Biology Important?Important?

Conservation & Environmental Conservation & Environmental Management – Management – human activities human activities such as destruction of habitats is such as destruction of habitats is causing the rapid loss of species. causing the rapid loss of species. Evolutionary principles figure Evolutionary principles figure prominently in managing endangered prominently in managing endangered species including providing species including providing guidelines for maintaining genetic guidelines for maintaining genetic diversity and prioritizing our diversity and prioritizing our conservation efforts.conservation efforts.

Why is Evolutionary Biology Why is Evolutionary Biology Important?Important?

Understanding Ourselves – Understanding Ourselves – Humans are inherently curious. Humans are inherently curious. Society throughout time has sought Society throughout time has sought answers to numerous questions. answers to numerous questions.

Evolution provides a scientific Evolution provides a scientific framework for asking questions framework for asking questions about ourselves and life around us.about ourselves and life around us.

Journal Topic #1How old do you think that the

earth is? How could one know? Reflect on what your time line looks like. What is interesting

about it. Why would a long timeline be important to

evolutionists?8 minutes

Group Timelines• Look at page 280 in your book

• Using National Geographics, Scissors, Glue, and Paper make the timeline from the book complete with pictures

• Make sure to label the years!!!

How is there so much

diversity?

Please briefly explain why you

think that there are so many types of

organisms.