• 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.
• 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.
Chapters 14 and 15
• 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.
= 500 million years ago
Earliest animals; diverse algae
Earliest multicellular eukaryotes?
Billions of years ago
• Life may have
developed from
nonliving materials
as early as 3.9
billion years ago
Earliest eukaryotes
Accumulation of atmospheric
O2 from photosynthetic
cyanobacteria
Oldest known prokaryotic fossils
Origin of life?
Formation of Earth
• 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.
CH
1. Water evaporates from
3
Water vapor
the oceans.
Electrode
2
2. The water vapor mixes
with the other gases in
Condenser
the early atmosphere.
3. Lightning adds activation
energy to begin an
Cold
water
reaction.
1
4. Water vapor cools and
4
condenses back to a
Cooled water
liquid.
containing
organic
5. New liquid water
compounds
5
HO
contains amino acids,
Sample for
sugars, and nucleotide
chemical analysis
bases. Monomers of proteins and nucleic acids can be produced
4
2
from non-living matter.
• 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.
• Researchers have tested ways of enclosing molecules in
membranes.
• The path from molecules to cells remains unresolved.
• 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.
• 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
• Similarities between some species (Meadowlarks) and variation
within a species (Humans) can make defining species difficult
• Humans exhibit extreme physical diversity
• A population or group of populations whose
members can interbreed and produce fertile
offspring.
• 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
1) Eastern and Western Meadowlark
• Very similar appearance but
different mating songs
2) Blue-footed boobies
• Courtship ritual specific to one area
3) Plant species
• Flower structures fit specific
pollinators
4) Liger (Lion/tiger hybrid)
• Ligers cannot reproduce.
5) Mule (Horse/donkey hybrid)
• Mules cannot reproduce.
Allopatric and Sympatric Speciation
• 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.
• 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: 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
Zygote
Meiotic
error
Selffertilization
2n = 6
Diploid
Offspring may
be viable and
self-fertile
4n = 12
Tetraploid
Unreduced diploid gametes
• 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
• 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.
Groups of Four:
• Rat Islands – establish your own species (Groups A to E)
Individual:
• Visualizing Vocabulary
• 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.
• 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.
Figure 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.
• 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.
Eurasian
Plate
North
American
Plate
African
Plate
Pacific
Plate
Nazca
Plate
South
American
Plate
Split
developing
Indo-Australian
Plate
Antarctic Plate
Edge of one plate being pushed over edge of
neighboring plate (zones of violent geologic events)
CENOZOIC
• This movement has
influenced the distribution of
organisms and greatly
affected the history of life.
Eurasia
Africa
India
MESOZOIC
Antarctica
PALEOZOIC
– Separation of continents
caused the isolation and
diversification of
organisms
– Continental mergers
triggered extinctions
Millions of years ago
South
America
Laurasia
• 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.
NORTH
AMERICA
ASIA
EUROPE
AFRICA
SOUTH
AMERICA
AUSTRALIA
= Living lungfishes
= Fossilized lungfishes
• Plate tectonics, the movements of Earth’s crustal plates, are
also associated with volcanoes and earthquakes.
• California’s
San Andreas
fault is a
boundary
between two
crustal plates
• By forming new islands, volcanoes can create opportunities for
organisms
• Example: Galápagos
• But volcanic activity can also destroy life
– Example: Krakatau
• 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.
?
Cretaceous
extinctions
90 million years ago
80
70
65
60
• 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
• 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.
• A method of analyzing organisms that classifies
them based on the order that they diverged from a
common ancestor.
• 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.
• 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.
• 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.
• 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.
• 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.
Compare 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
• 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.
Example:
The similar
appearance of
chromosomes among
chimpanzees,
gorillas, and
orangutans suggests
a shared ancestry.
• 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.
• 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.
• 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
• 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
• The greater the number of
derived characters shared
by groups, the more
recently the groups share a
common ancestor.