As you come in,• The Materials:• Pick up the ½-sheet practice problem, a vocabulary

packet, and a new notes packet.• Pass your Hardy Weinberg Fishy Frequencies Lab AND

Hardy Weinberg Practice Problems forward.• The Plan:• Discuss the Fishy Frequencies essay (due Monday).• Discuss the vocabulary packet (due Friday).• Watch Living Together video.• Begin Origin and Evolution of Species notes.

• The Assessment:• Hardy Weinberg Quiz (MONDAY)

• HOMEWORK:• Write essay, review Hardy Weinberg, and begin vocab

packet.

BenchmarkTuesday

As you come in,• The Materials:• Pass up the Fishy Frequencies essay.

• The Plan:• Review Hardy Weinberg Equation. (1 example)• Take Hardy Weinberg Quiz.• Rat Island Speciation Activity (45 minutes)• Begin Origin and Evolution of Species notes.

• The Assessment:• Speciation Vocabulary Quiz – FRIDAY

• HOMEWORK:• Review notes and continue speciation vocabulary assignment.

Benchmark

Tuesday

The Origin and Evolution of SpeciesChapters 14 and 15

Early Earth and the Origin of Living Things

Young Earth Theories• Theorists estimate that the Earth formed 4.6

billion years ago.• The early atmosphere probably contained

H2O, CO2, CO, N2, CH4, and little or no O2.• Volcanic activity, lightning, and UV radiation

were intense.• Fossilized prokaryotes date back to 3.5 billion

years.• Life may have formed from nonliving things

as long as 3.9 billion years ago.

Young Earth Timeline• Life may have developed from nonliving materials as early as 3.9 billion years ago

= 500 million years ago

Earliest animals; diverse algae

Earliest multicellular eukaryotes?

Earliest eukaryotes

Accumulation of atmosphericO2 from photosyntheticcyanobacteria

Oldest known prokaryotic fossils

Origin of life?

Formation of Earth

Bill

ions

of y

ears

ago

How did life originate?• Remember Spontaneous Generation? Francesco Redi

disproved the theory using fruit flies, meats, jars, maggots, etc.

• The Theory of Biogenesis resulted.• Only living organisms can produced other living organisms.

SO WHERE DID THE FIRST ORGANISM COME FROM?• 1920s Oparin and Haldane suggested that the Earth’s

early atmosphere has a certain mix of gases that could form simple organic molecules in the presence of water and energy sources (Sun and lightning).

• 1953 Miller and Urey proved that inorganic compounds can produce amino acids with water and electricity.

1. Water evaporates from the oceans.

2. The water vapor mixes with the other gases in the early atmosphere.

3. Lightning adds activation energy to begin an reaction.

4. Water vapor cools and condenses back to a liquid.

5. New liquid water contains amino acids, sugars, and nucleotide bases.

Water vaporCH4

Electrode

NH3 H 2

Condenser

Coldwater

Cooled watercontainingorganiccompounds

Sample forchemical analysis

H2O

1

23

4

5

Monomers of proteins and nucleic acids can be produced from non-living matter.

Forming Polymers from the Monomers• Proteins• Miller & Urey Experiment: The amino acids formed peptide

bonds for short periods of time to form very short protein strands, but the bonds broke quickly. No proteins resulted. Life did not form in the Miller & Urey experiment.• Theoretical explanation: Early amino acids were deposited on

clay. The amino acids stuck to the clay and others deposited on the same piece of clay. Eventually, bonds formed between the amino acids since they were all “stuck” on the clay.

• Nucleic Acids:• RNA is considered to have been early life’s genetic code. • RNA can be replicated using clay crystals.• Scientists believe that resulting RNA molecules developed

their own replication system over time.

Forming Cells from the Polymers• Researchers have tested ways of enclosing

molecules in membranes.• The path from molecules to cells remains

unresolved.

Origin of Species

Example of Speciation• The origin of new species is called speciation.• Evolution has generally been thought of as a very

gradual process•However, examples of rapid evolution have been observed

• One example of rapid evolution occurred among mosquitoes who migrated into the London underground

• In less than 150 years, Culex pipiens evolved into a new mosquito species, Culex molestus.

• The isolated mosquitoes adapted to their new underground environment.– They altered their prey, mating habits, and breeding

patterns• Environmental barriers that isolate populations are just

one of many mechanisms in the evolution of species.

What is a species?• Linnaeus used physical appearance to identify

species when he developed the binomial system of naming organisms.

• But appearance alone does not always define a species.• Example: Eastern and Western Meadowlarks

What is a species?• Similarities between some species (Meadowlarks)

and variation within a species (Humans) can make defining species difficult• Humans exhibit extreme physical diversity

Species• A population or group of

populations whose members can interbreed and produce fertile offspring.

Difficult to Establish a New Species • Two types of reproductive

isolation prevent new species:• Prezygotic Isolation: (BEFORE A

ZYGOTE FORMS) prevent reproduction by making fertilization unlikely

• Postzygotic Isolation: (AFTER A ZYGOTE FORMS) hybrid offspring cannot reproduce

Prezygotic vs. Postzygotic Reproductive Isolation

Let’s Identify the Type of Reproductive Isolation Illustrated1) Eastern and Western

Meadowlark• Very similar appearance but

different mating songs2) Blue-footed boobies• Courtship ritual specific to one

area3) Plant species• Flower structures fit specific

pollinators4) Liger (Lion/tiger hybrid)• Ligers cannot reproduce.

5) Mule (Horse/donkey hybrid)• Mules cannot reproduce.

Allopatric and Sympatric SpeciationMECHANISMS OF SPECIATION

Allopatric Speciation: Geographic barrier• Allopatric speciation: a physical barrier divides

one population into two or more populations• When a population is cut off from its parent stock,

species evolution may occur.• An isolated population may become genetically unique as its gene pool is changed by natural selection, genetic drift, or mutation.• As enough genetic differences are established, the two populations will no longer be able to breed successfully.

Allopatric Speciation: Islands• On the Galápagos Islands, repeated isolation and

adaptation have resulted in adaptive radiation of 14 species of Darwin’s finches.

• Adaptive radiation: a pattern of evolution; one species gives rise to many species in response to the creation of a new habitat or other ecological opportunity.

Sympatric Speciation• Sympatric Speciation: species evolves into a new

species without a physical barrier• In sympatric speciation, a new species may arise

without geographic isolation.• Example: Polyploidy in Plants• A failure in meiosis can produce diploid gametes• Self-fertilization can then produce a tetraploid

zygote

Parent species

2n = 6Diploid

Unreduced diploid gametes

4n = 12Tetraploid

Zygote

Meioticerror

Self-fertilization

Offspring maybe viable andself-fertile

A Few Patterns in Species Evolution• Three patterns common when new species evolve:• Adaptative Radiation: (discussed earlier)• Coevolution: a species evolves in close relationship with another species• Example: Moth and Comet Orchid –As the foot-long

flowers of the Comet Orchid developed, a moth with a foot-long tongue evolved to pollinate them.

• Convergent Evolution: Species with similar traits develop in different parts of the world due to similar climate and geography• Example: Mara and a rabbit – unrelated genetically

but developed similar body type, etc. because they inhabit similar niches

What’s a mara?

Two Theories on Rate of Speciation• Gradualism – Most

scientists believe that evolution proceeds in small, gradual steps.

• Punctuated Equilibrium –rapid spurts of genetic change cause species to diverge quickly; these periods punctuate longer periods when little changes in a species.

Speciation ActivitiesGroups of Four:• Rat Islands – establish your own species (Groups A

to E)

Individual:• Visualizing Vocabulary

Tracing Evolutionary History

Earth History • The fossil record chronicles macroevolution,

which is evolution on a grand scale.• A geologic time scale has been established

using the fossil record to organize the BIG PICTURE of how the earth and its inhabitants have evolved over millions of years.

Geologic Time Scale• The geologic time scale is a model that

expresses the major geological and biological events in Earth’s history.

• Organization of the Time Scale• Eon• Era• Period• Epoch

• Development of the Time Scale• As geologists study the strata (rock layers), they collect

fossils. • Radiometric dating uses chemistry of the rocks to measure

an approximate age.• Scientists have built the geological time scale based upon

fossils and the radiometric dating information.

Understanding the Time ScaleFigure 14.5 (page 397) • Geologic Time Scale begins with the Earth’s

formation 4.6 billion years ago. • Let’s discuss a scale model of the time scale.

• Interacting with the Scale• Geologic Time Scale Tutorial • Geologic Time Scale Worksheet (attached to tutorial)• Geologic Time Scale notes (fill-in after tutorial)• Reference pages 396-400 in your textbook.

Macroevolution Cause: Continental Drift• Continental drift has played a major role in

macroevolution.• Continental drift is the slow, incessant movement

of Earth’s crustal plates on the hot mantle.

PacificPlate

NorthAmerican

Plate

NazcaPlate

SouthAmerican

Plate

AfricanPlate

EurasianPlate

Splitdeveloping

Indo-AustralianPlate

Edge of one plate being pushed over edge of neighboring plate (zones of violent geologic events)

Antarctic Plate

• This movement has influenced the distribution of organisms and greatly affected the history of life.

– Separation of continents caused the isolation and diversification of organisms

– Continental mergers triggered extinctions

Mill

ions

of y

ears

ago

EurasiaCEN

OZO

ICM

ESO

ZOIC

PALE

OZO

IC

North America

AfricaIndiaSouth

America

AntarcticaAustralia

Laurasia

Gondwana

Pangaea

Macroevolution Cause: Continental Drift• Example of Isolation & Diversification :• Continental drift explains the distribution of

lungfishes, which are freshwater fish that use a modified swim bladder to breathe air.• Lungfishes evolved when Pangaea was intact during

the Paleozoic Era. • They were distributed around the world as crustal

plates shifted during the Mesozoic Era.• New species evolved as plates shifted to new

climates.

NORTHAMERICA

SOUTHAMERICA

EUROPE

AFRICA

ASIA

AUSTRALIA

= Living lungfishes

= Fossilized lungfishes

Macroevolution Cause: Continental Drift• Plate tectonics, the movements of Earth’s

crustal plates, are also associated with volcanoes and earthquakes.

• California’s San Andreas fault is a boundarybetween two crustal plates

Macroevolution Cause: Continental Drift• By forming new islands, volcanoes can create

opportunities for organisms• Example: Galápagos

• But volcanic activity can also destroy life– Example: Krakatau

Macroevolution: Mass Extinctions• Mass extinctions were followed by

diversification of life-forms.• At the end of the Cretaceous period (Mesozoic

Era), many life-forms disappeared, including the dinosaurs.• These mass extinctions may have been a result of an asteroid impact or volcanic activity.

• Every mass extinction reduced the diversity of life.– But each was followed by a rebound in

diversity.– Mammals filled the void left by the

dinosaurs.

90 million years ago 80 70 65

Cretaceousextinctions

60

?

Macroevolution: Mass Extinctions• Key adaptations may enable species to proliferate

after mass extinctions.• Adaptations that have evolved in one

environmental context may be able to perform new functions when conditions change.

• Example: Plant species with catch basins, an adaptation to dry environments

CONNECTION: You may be living through a Mass Extinction Event right now…

• Many scientists think a Mass extinction event is happening now.

• A decrease in biodiversity is a threat to us all.

• Humans are responsible for much of the problem due to habitat degradation, pollution, over-hunting, and poor conservation habits.

Cladistics

What is Cladistics?• A method of analyzing organisms that

classifies them based on the order that they diverged from a common ancestor.

Necessary Vocabulary: Phylogenic Species Concept• Phylogenic Species Concept:

BASED ON ANCESTORS• Phylogeny is the evolutionary history of a

species.• The phylogenic species concept defines a

species as a cluster of organisms that is distinct from other clusters and shows evidence of a pattern of ancestry and descent.

Necessary Vocabulary: Typological Species Concept• Typological Species Concept:

BASED ON APPEARANCE•Aristotle and Linnaeus thought of each species as a distinctly different group of organisms based on physical similarities.•Based on the idea that species are unchanging, distinct, and natural types.

Necessary Vocabulary: Biological Species Concept• Biological Species Concept:

BASED ON REPRODUCTION•The biological species concept defines a species as a group of organisms that is able to interbreed and produce fertile offspring in a natural setting.

Necessary Vocabulary: Characters• Characters: inherited features that vary

among species• To classify a species, scientists construct

patterns of descent by using characters.• Characters can be morphological or

biochemical.

Necessary Vocabulary: Morphological Characters• Characters: inherited features

that vary among species• Shared morphological characters

suggest that species are related closely and evolved from a recent common ancestor.

• Analogous characters are those that have the same function but different underlying construction.

• Homologous characters might perform different functions, but show an anatomical similarity inherited from a common ancestor.

Necessary Vocabulary: Evolutionary CharactersCompare birds and dinosaurs:• Hollow bones• Theropods have leg, wrist,

hip, and shoulder structures similar to birds.

• Some theropods may have had feathers.

Haliaeetus leucocephalus

Oviraptor philoceratops

Necessary Vocabulary: Biochemical Characters• Scientists use biochemical characters, such

as amino acids and nucleotides, to help them determine evolutionary relationships among species.

• DNA and RNA analyses are powerful tools for reconstructing phylogenies.

Necessary Vocabulary: Biochemical CharactersExample:The similar appearance of chromosomes among chimpanzees, gorillas, and orangutans suggests a shared ancestry.

Humans even share entire gene sequences with other organisms; again, suggesting shared ancestry.

Necessary Vocabulary: Molecular Clock• Cladistics organizes

organisms based upon when they diverged from a common ancestor.

• Scientists use molecular clocks to compare the DNA sequences or amino acid sequences of genes that are shared by different species.

• The data helps to put organisms in chronological order.

Necessary Vocabulary: Molecular Clock• How Molecular Clocks Work:• Differences in the amino acid sequences between

DNA of related organisms indicate the presence of mutations.• The more mutations are present, the more time has

passed since the organism diverged from the common ancestor.• Simple – If organism A has more mutations (more

differences from the ancestor), then it diverged more recently. More difference = more time = “newer” organism

• In the 1960s, scientists developed molecular clocks. They thought that mutations occur at regular intervals (like time).• They were wrong…lots of factors affect the rate of

mutations.• Therefore, molecular clocks aren’t very reliable on

their own. When used in conjunction with other resources like the fossil record, they are useful.

Necessary Vocabulary: Molecular Clock• Factors that Affect the Rate of Mutation:• Type of mutation•Where the mutation is in the genome• Type of protein that the mutation affects• Population in which the mutation occurs

Necessary Vocabulary: Phylogenetic Reconstruction• Cladistics reconstructs phylogenies (“family

trees) based upon shared characters.• Scientists consider two main types of

characters:•Ancestral characters: a character found within the entire line of descent of a group of organisms•Derived characters: a character that is present in members of one group of the line but not in the common ancestor

Cladograms• The greater the

number of derived characters shared by groups, the more recently the groups share a common ancestor.

Using Molecular Biology to Create a Cladogram

(Human, fish, frog, chicken, shark)