Week 4
• Chapters 13-16
•
•
•
•
Evolution
Evolution in Populations
The History of Live
Diversity as a result…
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Chapter 13
• Building on the ideals of genes,
chromosomes, traits, and reproduction
… let’s look at the theory derived
before the chemical process (DNA etc.)
was discovered…
• Principles of Evolution
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How Did Evolutionary
Thought Evolve?
• Modern biology is based on the understanding that life
evolved
• Early Biological Thought Did Not Include the Concept of
Evolution, but took tens of centuries to ‘be ready’ for the
structure
• Pre-evolution: All creatures were created simultaneously
by God.
• Plato and Aristotle; each animal a reflection of its ‘ideal
form’ and were characterized in a ‘linear’ structure.
• Held for 2000+ years…
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…to explore strange, new,
worlds…
• Exploration of New Lands Revealed a Staggering
Diversity of Life
• Europeans who explored Africa, Asia and the
Americas took naturalists along
• By the 1700’s the scope of diversity was
emerging
• Some naturalists began to notice similarities and
patterns – and noticed that the same creatures
were NOT present worldwide (species were
localized)
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Early Speculations…
• A Few Scientists Speculated That Life Had
Evolved
• In the early 1700’s one man (Georges Louis
LeCleac) speculated that maybe there had been
few original species, but they had changed over
time
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Enter fossils stage right…
• Fossil Discoveries Showed That Life Has
Changed over Time
• Excavations for roads, mines and canals = rocks
that looked like parts of living creatures…
– Types of fossils (p. 217)
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eggs in nest
fossilized feces
(coprolites)
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bones
footprint
skin impression
Layers and Bones
• And Rock types came in layers with distinct
fossils in them (The Grand Canyon of the
Colorado River (p. 217))
– Fossils of extinct organisms (p. 218)
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230mya
youngest
rocks
oldest
rocks
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150mya
65mya
How Did Evolutionary
Thought Evolve?
• Some Scientists Devised Nonevolutionary
Explanations for Fossils
• Catastrophism – (Georges Cuvier – early 1800’s)
– Great Flood
– other global disasters
– = layers of rock and animals killed
• A number of modern authors (including the
‘Creation Research Institute’ – CRI – California)
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Evolution evolution
• Geology Provided Evidence That Earth Is Exceedingly
Old
• Rivers, seas, and lakes lay down layers of silt
• Volcanoes lay down layers of rock (lava flows,
pyroclatic flows)
• Charles Lyell, James Hutton  unifomitarianism
• = Natural (slow) processes did most of the geologic
building and fossil burying
• BUT 1000’s of feet of rock – LONG TIME PEROIDS!
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More evolving
• Some Pre-Darwin Biologists Proposed Mechanisms
for Evolution
– Jean Baptiste Lamark (early 1800’s) = saw deeper fossils
simpler, shallower more like life now
– Species strive toward ‘perfection’, improvements parents
make (Giraffe necks) are passed on. (Not true.)
• Darwin and Wallace Proposed a Mechanism of
Evolution
– Biologists already comfortable that things probably evolved,
but how and why?
– Darwin’s finches, residents of the Galapagos Islands (p. 220)
supplied the WHY.
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Large ground finch, beak
suited to large seeds
Warbler finch, beak
suited to insects
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Small ground finch, beak
suited to small seeds
Vegetarian tree finch, beak
suited to leaves
How Does Natural Selection Work?
• Each generation differs slightly from the
members of the preceding generation (no
special differences, just differences)
• These small changes lead over LONG
periods of time to very big alterations.
• The alterations that allow more to survive
stick, those that lead to early death don’t get
passed on.
• Natural Selection
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Potential for
rapid reproduction
Relatively constant resources
and population size over time
Competition for survival
and reproduction
Variability in
structures and behaviors
NATURAL SELECTION:
On the average, the fittest
organisms leave the most offspring
Observation
Conclusion based on observation
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Some variability
is inherited
EVOLUTION:
The genetic makeup of the population
changes over time,
driven by natural selection
Charles Darwin
• Interested in collecting species of things as a
young man (and categorizing them)
• Had a degree in theology
• Served aboard the HMS Beagle and got to
‘see the world’
– Especially the Galapagos Islands and the
tortoises there.
– Each island had different variations of species
from each other and from Europe
• Published “On the Origin of Species” in 1859
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How Does Natural Selection
Work?
• Modern Genetics Confirmed Darwin’s
Assumption of Inheritance
– The lack of a knowledge of genetics (still
about 100 years away) was a hole in their
theory. They didn’t have the HOW
answered yet.
• Bottom line: Natural Selection Modifies
Populations over Time (based on
environmental stressors)
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How Do We Know That
Evolution Has Occurred?
• An overwhelming body of evidence permits
no other conclusion.
• No one has come up with a better
explanation for species variation, the fossil
record (growing all the time), and
comparative anatomy, embryology,
biochemistry and genetics.
• Fossils Provide Evidence of Evolutionary
Change over Time
– Figure 13.6 The evolution of the horse (p. 224)
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Equus
Archaeohippus
Anchitherium
Merychippus
Mesohippus
forefoot
tooth
Hyracotherium
Paleotheres
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browsing
millions of years ago
Hipparion
grazing
Pliohippus
How Do We Know That
Evolution Has Occurred?
• Comparative Anatomy Gives Evidence of
Descent with Modification
– Features in today’s species yield structural
similarities that point to their common ancestors
– Homologous Structures Provide Evidence of
Common Ancestry
• Internally similar structures across vastly different
species 
• Homologous structures (p. 225)
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humerus
ulna
Pterodactyl
carpals
Dolphin
metacarpals
Dog
phalanges
Human
Bird
Bat
FLYING
Seal
Sheep
Shrew
SWIMMING
RUNNING
GRASPING
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How Do We Know That
Evolution Has Occurred?
– Functionless Structures Are Inherited from Ancestors
• Some structures are carried on but don’t have a function (they
don’t hinder survival, but don’t matter either)
– Molar teeth in vampire bats (don’t chew)
– Wisdom teeth in humans (most mouths too small), the appendix,
body hair, tail bone – to name a few
– Pelvic bones in whales and certain snakes
– Whales with remains of back legs inside them
• Figure 13.8 Vestigial structures (p. 226)
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Salamander
Baleen whale
Boa constrictor
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Salamander
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Baleen whale
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Boa constrictor
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How Do We Know That
Evolution Has Occurred?
– Some Anatomical Similarities Result from
Evolution in Similar Environments
– Insect wings and bird wings did NOT come
from a common ancestor’s feature/trait
– Survival favored those who could fly
– Example of convergent evolution
– And the traits/structures are called:
• Figure 13.9 Analogous structures (p. 227)
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Modern Biochemical and Genetic
Analyses Reveal Relatedness
among Diverse Organisms
• All living cells are extremely similar (even
prokaryotes and eukaryotes)
• DNA and protein structures virtually identical
• All use RNA, ribosomes, same genetic code,
same 20 amino acids to build proteins
• ATP carries energy
• Planet wide ‘handedness of protein’
• Even Embryological Similarity Suggests
Common Ancestry (lemur, pig, human)
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What Is the Evidence That
Populations Evolve by Natural
Selection?
• Controlled Breeding Modifies
Organisms
– Artificial Selection – Breeding!
– Pets, Horses, Crops, Flowers, etc.
– Figure 13.11 Dog diversity illustrates
artificial selection (p. 228)
(Wolf  Dog easily interbreed still)
Only few 1000 years. Human directed.
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What Is the Evidence That
Populations Evolve by Natural
Selection?
• Evolution by Natural Selection Occurs Today
– Brighter Coloration Can Evolve When Fewer Predators Are Present
(fish-guppies in Trinidad)
– Natural Selection Can Lead to Pesticide Resistance (‘Combat’ vs.
roaches)
– Experiments Can Demonstrate Natural Selection (colony of lizards in
the Bahamian islands- leg changes in 14 yrs)
– Selection Acts on Random Variation to Favor the Phenotypes That
Work Best in Particular Environments – a number of generations is
needed
• REMEMBER – Natural Selection does not DECIDE to make a certain
change…
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Chapter 14
• How Populations Evolve
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How Are Populations, Genes,
and Evolution Related?
• Genes and the Environment Interact to
Determine Traits
– A gene is a segment of a DNA located at a particular
place on a chromosome
– Different species might have different sequences of
T, A, C and G (nucleotide sequences) called alleles.
– In a population there are two or more alleles of each
gene
– The trait given by the dominate or matching genes
will help or hurt a populations chance for survival
• (Evolution is a population, not individual, level
phenomena)
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It’s in the genes…
• The Gene Pool Is the Sum of the
Genes in a Population
– Frequency, distribution and and inheritance
of alleles in the population
• Evolution Is the Change of Allele
Frequencies within a Population = a
drift in the numbers
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The more things change…
• The Equilibrium Population Is a Hypothetical
Population in Which Evolution Does Not
Occur
–
–
–
–
–
–
Hypothetical/ideal
There can’t be mutations
No gene flow between populations
Very large population
Mating is random
No natural selection
• If any of the above is not true about a
population – evolution happens!
(most important components in pink)
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What Causes Evolution?
• Mutations Are the Original Source of Genetic
Variability
– Mutations Are Rare But Important
• In humans, only 1 in 100,000 to 1,000,000 human
gametes carry a mutation of a given gene
• New alleles and variations can come into existence
– Mutations Are Not Goal Directed
• It’s just some “work” and some don’t
• Figure 14.1 Mutations occur spontaneously (p. 239)
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1 Start with bacterial
colonies that have never
been exposed to antibiotics.
2 Use velvet to transfer
colonies to identical positions
in three dishes containing the
antibiotic streptomycin.
3 Incubate dishes.
4 Only streptomycin-resistant
colonies grow. The few colonies
are in the exact same positions
in each dish.
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Disaster! Everyone out of the
pool…
• Allele Frequencies May Drift in Small
Populations
– Some being removed from the gene pool don’t
hurt the overall genetic makeup of the population
– Population Size Matters
• Genetic drift = the process of changes in the population
alleles due to accidents/removal of some members (or
lack of specific genes being passed on.
• 14.2 The effect of population size on genetic drift (p.
240)
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Population size = 10,000
frequency of allele A
frequency of allele A
Population size = 4
generation
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generation
frequency of allele A
Population size = 10,000
generation
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frequency of allele A
Population size = 4
generation
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What Causes Evolution?
– A Population Bottleneck Is an Example of
Genetic Drift
• A disaster (or over hunting) happens and cuts
the numbers way down
• The small population is all that is around to
pass on it’s genes.
• Figure 14.3 Population bottlenecks reduce
variation (p. 241)
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resulting population
original population
event causing
bottleneck
time
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Northern elephant seal – almost extinct in the 1800’s
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The cheetah also went through a population bottleneck in the last century
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What Causes Evolution?
• Genotypes Are Not All Equally Beneficial
– Any small advantage will matter to the population over
time/generations
– Antibiotic Resistance Evolves by Natural Selection –
Penicillin during WWII – (true for all antibiotics =
evolution  resistive bugs)
– Penicillin Resistance Illustrates Key Points about
Evolution
• Resistance had to have ALREADY existed in the bacteria’s
DNA- the environmental pressured FAVORED the trait
• Individuals are NOT changed – fitness is favored
• The same trait may NOT be as beneficial later – when different
forces are at work:
Figure 14.4 A compromise between opposing environmental
pressures (p. 242)
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How Does Natural Selection
Work?
• Natural Selection Stems from Unequal Reproduction
(not just survival)
• Natural Selection Acts on Phenotypes (outward traits
that aid in survival and reproduction – can be
ANYTHING!)
• Adaptations are characteristics of an individual that
help it survive and reproduce
• “Live Long and Prosper”
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Pheno-what?
• Some Phenotypes Reproduce More Successfully Than Others
– An Environment Has Nonliving and Living Components
• Climate, water, minerals, storms (extremes) etc.
• Pests, competitors, food supply, diseases etc.
– Competition Acts As an Agent of Selection
• Everyone needs resources
(think of hurricane evacuees and gas stations)
• Members of the same species compete the most severely for the
same resources
(think of natural gas cars vs. gasoline based SUV’s during a
hurricane evacuation)
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Predator/Prey
• Both Predator and Prey Act As Agents of Selection
– Constant feedback and pressure in this ‘arms race’ =
coevolution
– Example wolves select against slow deer, and deer select
against slow wolves
• Sexual Selection Favors Traits That Help an
Organism Mate
– Figure 14.5 Competition between males favors the
evolution, through sexual selection, of structures for
ritual combat (p. 244)
• Who has the best song, smell, look, strength, etc.?
• Figure 14.6 The peacock’s showy tail has evolved
through sexual selection (p. 245)
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The winner (tougher) mates, the looser
probably doesn’t. (In humans = high
paying tech jobs…)
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What Is a Species?
• Biologists Need a Clear Definition of Species
– Pre-Darwin, species referred to ‘types’ from the
Bible.
• Species Are Groups of Interbreeding
Populations and evolve independently
because of that.
– Still doesn’t help us with asexual reproduction
– Can’t observe, sometimes, if two creatures can
actually breed successfully
• Appearance Can Be Misleading
– Figure 14.7 Members of a species may differ in
appearance (p. 246)
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(a) The myrtle warbler
and (b) Audubon’s
warbler are members of
the same species.
But now we know they
can and do interbreed
and have healthy
offspring.
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How Do New Species Form?
• Darwin never gave us a a complete mechanism of
speciation
• An ornithologist Ernst Mayer did…
• Geographical Separation of a Population Can Lead
to Speciation = Isolation of the populations
– Figure 14.8 Geographical isolation (p. 246)
• Under Some Conditions, Many New Species May
Arise Genetic variation must happen during this
isolation
– Figure 14.9 Or Adaptive radiation (p. 247) changes
happen due to radical change in environment (and
survival pressure)
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Grand Canyon North Rim and South Rim Squirrels. Isolated. But different
now?  unknown
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300 species of
cichlid fish live
in Lake Malawi
in East Africa.
Found nowhere
else.
Started from a
common first
population < 1
million years ago
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How Is Reproductive Isolation
between Species Maintained?
• Species must not be able to mate if they
come in contact again! (for them to be
considered separate)
• Premating Isolating Mechanisms Prevent
Mating between Species
– Members of Different Species May Be
Prevented from Meeting (physical isolation)
– Different Species May Occupy Different
Habitats
• Figure 14.10 Ecological isolation (p. 248)
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A female fig wasp is
carrying fertilized eggs
from a mating that took
place within a fig. She
will find another fig of
the same species, enter
it through a pore, lay
eggs, and die.
Only that particular type
of fig will do. No other
fig wasp will use that
type.
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How Is Reproductive Isolation
between Species
Maintained?
– Different Species May Breed at Different
Times
• Figure 14.11 Temporal isolation (p. 248)
• Bishop Pines release pollen at different times
of the year (but CAN product viable offspring in
the lab/greenhouses)
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How Is Reproductive Isolation
between Species Maintained?
• Different Species May Have Different
Courtship Rituals
– Birdsong, chirping, coloration, ‘dances’ 
behavioral isolation
• Species’ Differing Sexual Organs May Foil
Mating Attempts
– Obvious in animal world, in plant world; flowers
may attract different pollinators.
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Postmating
• Postmating Isolating Mechanisms Limit Hybrid
Offspring
– One Species’ Sperm May Fail to Fertilize Another Species’
Eggs
• gametic incompatibility
– Hybrid Offspring May Survive Poorly
• Behavior might be mixture of adults and not work to protect it in
the wild
– Hybrid Offspring May Be Infertile
• Table 14.1 Mechanisms of Reproductive Isolation (p.
250)
– Mules (horse+donkey)
– Liger (male lion + female tiger (zoos))
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What Causes Extinction?
• 99.9% of all species that have ever existed
are now extinct!
• Interactions with Other Species May Drive a
Species to Extinction
– South and North America joining ~ 2.5 mya
– Far more N.A. species survived for a still
unknown reason
• Habitat Change and Destruction Are the
Leading Causes of Extinction
– Possibly ½ of all species will be extinct in 50 yrs
– Figure E14.2 Endangered by habitat destruction
(p. 251)
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Chapter 15
• The History of Life on Earth
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How Did Life Begin?
• Life came into existance as it was
‘needed’ = Spontaneous Generation
• Experiments Refuted Spontaneous
Generation
– Figure 15.1 Spontaneous generation
refuted (p. 258)
– Francesco Redi  disproved maggots
spontaneously generate in meat
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no growth
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growth
How Did Life Begin?
• The First Living Things Arose from
Nonliving Ones
– Our present day oxygen rich atmosphere
would have been too corrosive to let
molecules organize into early life
– Prebiotic (before life) evolution of
molecules
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Let there be life…
• Organic Molecules Can Form
Spontaneously under Prebiotic Conditions
– We see them in comets, deep space, Jupiter’s
and Titan’s atmospheres
– Figure 15.2 The experimental apparatus of
Stanley Miller and Harold Urey (p. 259)
• Methane, ammonia, hydrogen, water vapor + lightning
• amino acids, short proteins, nucleotides, ATP + others
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electric spark
chamber
CH4
boiling chamber
water
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condenser
NH3
H2
H2O
cool water
flow
How Did Life Begin?
• Organic Molecules Can Accumulate under
Prebiotic Conditions – no predators, no oxygen =
an organic molecule soup in the oceans
(primordial soup)
• Organic Molecules May Have Become
Concentrated in Tidal Pools (needed to be
protected by rocks (etc.) from the sun’s UV light
(no ozone layer))
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To gene or not to gene?
• RNA May Have Been the First Self-Reproducing
Molecule
– DNA needs proteins to reproduce, but proteins need DNA to be
created
– A small RNA molecule can reproduce itself without an enzyme or
protein if it has a special small RNA molecule present called a
ribozyme (acts like an enzyme and a ribosome)
– dozens of ribozymes are known to exist now
– copies have lots of errors (mutations) = many ‘tries’ quite quickly
• Membrane-Like Microspheres May Have Enclosed
Ribozymes
– Formed by wave action on organic molecule soup-ocean
– Figure 15.3 Did microspheres enclose the earliest cells?
261)
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2006
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How Did Life Begin?
• But Did All This Happen?
• Consistent with observations, but not
certain.
• Vast expanses of time are needed (we DO
have a few billion years to play with), and it
can’t be observed. There is no record of the
earliest processes (let alone the makeup of
the first atmosphere).
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What Were the Earliest
Organisms Like?
• Earth cooled in a few 100 million years.
• Water appeared and life followed ‘soon’
after (earliest fossil = 3.5 billion years
old, Earth is 4.5 billion years old,
earliest life about 3.9 billion years?)
• Table 15.1 The History of Life on Earth
(p. 263)
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first humans
(11:59:40 P.M.)
formation
of Earth
first flowers
first Earth
rocks
invasion of land
by plants
first
prokaryotes
first
animals
billions of
years ago
first
multicellular
organisms
first eukaryotes
free oxygen begins
to accumulate
Earth’s history projected on a 24-hour day
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What Were the Earliest
Organisms Like?
• The First Organisms Were Anaerobic
Prokaryotes
– Genetic material NOT confined in a nucleus
– Gained nutrients and energy by absorbing stuff
around them
– No oxygen = anaerobic life
– Primitive bacteria
– Molecules that carried energy were lacking at first
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Using the Sun
• Some Organisms Evolved the Ability to Capture the Sun’s Energy
– Sunlight + hydrogen (probably hydrogen sulfide like today’s purple
photosynthetic bacteria do)
– Then the volcanoes calmed down and hydrogen sulfide ran low
– So they had to switch to water as the hydrogen source
• Photosynthesis Increased the Amount of Oxygen in the
Atmosphere
– This released oxygen from the water and put into the atmosphere 2.2
billion years ago
– The new component of the atmosphere combined with the Earth’s crust
(rusted the planet)
– = Red rock/red beds/ red soil seen planet wide in the oldest crust
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The Age of the Microbes
• Aerobic Metabolism Arose in Response to the Oxygen
Crisis
– Oxygen = poison to life then- killed much of what was on the Earth
– Cells developed a way to handle the oxygen
– the Age of the Microbes where they used oxygen as part of their
metabolism
– Much more energy was available to the cells now!
– Early bacteria would be good things to eat…
• Some Organisms Acquired Membrane-Enclosed
Organelles
– Mitochondria and Chloroplasts May Have Arisen from
Engulfed Bacteria
• Figure 15.4 The probable origin of mitochondria and
chloroplasts in eukaryotic cells (p. 265)
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aerobic
bacterium
1 Anaerobic, predatory
prokaryotic cell engulfs an
aerobic bacterium.
2 Descendants of
engulfed bacterium evolve
into mitochondria.
3 Mitochondria-containing
cell engulfs a photosynthetic
bacterium.
4 Descendants of
photosynthetic bacterium
evolve into chloroplasts.
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aerobic
bacterium
1 Anaerobic, predatory
prokaryotic cell engulfs an
aerobic bacterium.
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2 Descendants of
engulfed bacterium evolve
into mitochondria.
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3 Mitochondria-containing
cell engulfs a photosynthetic
bacterium.
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4 Descendants of
photosynthetic bacterium
evolve into chloroplasts.
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Resistance is futile…
– Evidence for the Endosymbiotic Hypothesis Is Strong
• Eukaryotic organelles and living bacteria share many
similarities
• Mitochondria, chloroplasts, centrioles each contain their
own minute supply of DNA which may be the descended
remains of the original bacteria
• Figure 15.5 Symbiosis within a modern cell (p. 266)
– Chloroplasts in today’s plant cells may have resembled
Chlorella – a green photosynthetic, single-celled algae living
symbiotically within the cytoplasm of the Paramecium in the
next frame…
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What Were the Earliest
Multicellular Organisms Like?
• Larger cells would be harder to engulf,
so they would survive better
• But there is a limit to cellular size (see
Week 1’s lecture)
• So…Some Algae Became Multicellular
– About 1 billion years ago
– brown kelp (up to 200 feet long) today
probably directly descends from this stage
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Wee beasties…
• Animal Diversity Arose in the Precambrian Era
– About 610 to 544 million years ago = first fossils (0.61 to
.544 billion years ago) – shells then bones
– First ‘animals’ were invertebrate (no backbone) (610 mya)
– Many of these are unique to anything alive today and may
have no living decedents
– Then an explosion of variations appear – life of all kinds
– Predators and prey feedback started, speed was needed,
chemical protections, central nervous systems etc.
– 530 mya the first fish with backbones (vertebrates)
– Figure 15.6 Diversity of ocean life during the Silurian
period (p. 267) (440 to 410 million years ago (mya))
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How Did Life Invade the Land?
• Some Plants Became Adapted to Life on Dry
Land
–
–
–
–
Started at the ocean margins
Multicellular land plants started
Waterproof coatings retained water
Primitive Land Plants Retained Swimming Sperm
and Required Water to Reproduce
• Figure 15.7 The swamp forest of the Carboniferous
period (p. 269)
• Earth’s climate was warm and moist – 360 to 286 mya
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How Did Life Invade the
Land?
– Seed Plants Encased Sperm in Pollen Grains
• Drier climate
• Eggs retained in parent plant (protection) sperm
airborne = pollen (Up to only 375 mya)
• Conifers (Seed cones – pine trees) appeared
286-245 mya)
– Flowering Plants Enticed Animals to Carry
Pollen
• New land animals used starting about 140 mya
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Land beasties
• Some Animals Became Adapted to Life on
Dry Land
– First were arthropods (today includes insects,
spiders, scorpions, centipedes and crabs)
– Had an exoskeleton for protection
– Dragonflies with 1 yard wingspan appear
– Amphibians Evolved from Lobefin Fishes
(400 mya)
• Figure 15.8 A fish that walks on land (p. 270)
• Sack off stomach like a primitive lung – could use
oxygen from air and water
• Got to other ponds where the eating was better
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The modern mudskipper.
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How Did Life Invade the Land?
– Reptiles Evolved from Amphibians
• Amphibians declined when the world became
somewhat cooler and drier
• Reptile adaptations:
– Shelled, waterproof eggs (enclosed water supply, food and
developing embryo)
– Scaly, waterproof skin so they could stay on land
– Improved lungs that could supply enough oxygen to the
cells to support action
• Then the world warmed and became moist again=
LARGE reptiles took over
• The Age of Dinosaurs 165 mya to 65 mya
• VERY SUCCESSFUL!
• Figure 15.9 A reconstruction of a Cretaceous forest (p.
270)
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How Did Life Invade the
Land?
– Heat loss was a problem for the big reptiles
– One group of small reptiles began to develop hair,
the other group began to develop feathers
– Reptiles Gave Rise to Both Birds and Mammals
– Birds- feathers = insulation then helped (perhaps)
them glide from tree to tree
• Full flight capable about 150 mya
– Furry Mammals = also active at night when
reptiles were slow/sluggish (cold) – at least 55
mya
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Quick Definition Slide
•
•
•
•
•
•
•
•
The Animal …Kingdom
sharing with all other members of this group the need to feed on organic
matter (unlike plants which can create energy using light and minerals)
The Chordate (or vertebrate) … Phylum
sharing with all other members of this group of animals, a back bone with a
hollow nerve chord
The Mammal … Class
sharing with all other members of this group of vertebrates, the ability to feed
their offspring on milk and having a body covering which includes fur
The Primate … Order
Sharing with all other members of this group of mammals, a thumb that can
be opposed to the other digits, binocular vision and various more broadly
defined characteristics (including high intelligence, relatively long maturation
period for the young, dental similarities, tendency for complex social
organization, and generally bearing one or two young)
The Lemuridae … Family
Sharing with other members of this group of primates, a slightly longer nose,
smaller brain, long slender limbs, a tail, more specific dental features
including the grooming comb formed by the lower incisor and canine teeth
The Lemur … Genus
Sharing with other members of this group of lemurs, scent marking methods,
vocalizations, aspects of social structure and overall body shape
The Ring-tailed Lemur … Species
A species is the primary unit of biological classification or taxonomy. Species
members share a basic genetic similarity and can interbreed and produce
viable or fertile offspring
.
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What Role Has Extinction
Played in the History of Life?
• Evolutionary History Has Been Marked
by Periodic Mass Extinctions
– There is a HUGE list of extinct
species/families/kingdoms etc.
– Figure 15.10 Mass extinctions (p. 272)
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millions of years ago
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number of families
Tertiary
Cretaceous
Jurassic
Triassic
Permian
Carboniferous
Devonian
Silurian
Ordovician
Cambrian
What Role Has Extinction
Played in the History of Life?
• Climate Change Contributed to Mass
Extinctions
– Figure 15.11 Continental drift from plate tectonics
(p. 273)
– Continents “float”
– 350 mya N. America was mostly at the equator
– The Atlantic ocean is still widening at a few
centimeters (almost an inch) a year.
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Eurasia
North
America
India
Africa
South
America
Australia
Antarctica
340 million years ago
Eurasia
North
America
PANGAEA
South
America
Africa
India
Australia
Antarctica
225 million years ago
North
America
Eurasia
LAURASIA
EAST
GONDWANA
WEST GONDWANA
South
America
Africa
India
Australia
Antarctica
135 million years ago
North
America
Europe
Asia
Africa
South
America
Australia
Antarctica
Present
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North
America
Eurasia
Africa
South
America
340 million years ago
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India
Australia
Antarctica
Eurasia
North
America
PANGAEA
South
America
Africa
India
Antarctica
225 million years ago
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Australia
North
America
Eurasia
LAURASIA
EAST
GONDWANA
WEST GONDWANA
South
America
Africa
India
Antarctica
135 million years ago
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Australia
North
America
Europe
Asia
Africa
South
America
Australia
Antarctica
Present
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http://www.btinternet.com/~connectionsinspace/Mapping/Continental_Drift/
body_continental_drift.html
http://www.dinosauria.com/dml/maps.htm
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What Role Has Extinction
Played in the History of Life?
• Catastrophic Events May Have Caused the
Worst Mass Extinctions
• A giant meteor hit the Gulf of Mexico 65 million
years ago…
• The Chicxulub crater – 100 miles wide
• 10 mile wide rock
• Possibly Darkened the Earth for decades…
• Shut down photosynthesis planet wide
• Possible trigger for extinction of the dinosaurs
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How Did Humans Evolve?
• Humans Inherited Some Early Primate
Adaptations for Life in Trees
– Fossil evidence of human evolution is
comparatively scarce so this IS speculative.
– Humans are members of the mammal group
known as primates (includes lemurs, monkeys
and apes)
– Early humans probably tree based – fruits, leaves
– (Common ancestor to present day primates)
– We have NOT evolved from apes or monkeys
– Oldest primate fossils = 55 million years old (first
primates might be earlier)
– Figure 15.12 Representative primates (p. 274)
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lemur
tarsier© 2006 Pearson Prentice Hall, Inc.
Copyright
lion-tail macaque monkey
How Did Humans Evolve?
– Binocular Vision Provided Early Primates with Accurate Depth Perception
• Gives depth perception
• Color vision allows fruit to be seen among leaves
– Early Primates Had Grasping Hands
• Capable of delicate work (precision grip)
• And grasping heavy items (power grip)
– A Large Brain Facilitated Hand-Eye Coordination and Complex Social
Interactions
• Brain to body size of primates = greatest ratio known
• Complex signals could be developed  language
• The Oldest Hominid Fossils Are from Africa
– hominid line diverged from ape line 5-8 million years ago
– Figure 15.13 The earliest hominid (p. 274)
– Figure 15.14 A possible evolutionary tree for humans (p. 275)
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Ardipithecus ramidus
Sahelanthropus tchadensis
Orrorin tugenensis
millions of years ago
A. africanus
Australopithecus afarensis
A.anamensis
A. biosei
A. robustus
Homo ergaster
H. habilis
H. erectus
H. neanderthalensis
H. heidelbergensis
H. sapiens
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Ardipithecus ramidus
Sahelanthropus tchadensis
…..……..?
…..……..?
How Did Humans Evolve?
• The Earliest Hominids Could Stand and Walk Upright
– Legs shorter relative to their height than modern human
– knees allowed them to straighten
– later hominids could carry weapons, tools…
• Several Species of Australopithecus Emerged in Africa
– emerged 3.9 to 4.1 million years ago
– went extinct 1.2 million years ago
• The Genus Homo Diverged from the Australopithecines 2.5
Million Years Ago
–
–
–
–
body and brain were larger
homo habilis kept ape-like long arms and short legs
homo ergaster had proportions more like us
a branch from homo ergaster led both to Neanderthals and to homo
sapiens
• The Evolution of Homo Was Accompanied by Advances in
Tool Technology
– Timeline of hominids…
– Figure 15.15 Representative hominid tools (p. 276)
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Homo habilis
Homo ergaster
Homo neanderthalensis
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Homo habilis
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Homo ergaster
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Homo neanderthalensis
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How Did Humans Evolve?
• Neanderthals Had Large Brains and Excellent
Tools
– Appear 70,000 years ago
– Extinct by 30,000 years ago
– Not like movie cavemen. Were similar to present man.
More heavily muscled than modern man, walked
upright.
– Brains slightly larger than present man.
– Used tools.
– DNA has been isolated and analyzed. Are different
from modern man – separate species that diverged
100,000’s of years earlier.
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Cousins
• Modern Humans Emerged Only 150,000 Years
Ago
– Anatomically modern humans appeared in Africa then
– Cro-Magnons appeared 90,000 years ago (named after a
French district where they were discovered)
– Domed heads, smooth brows, prominent chins like us
– More sophisticated than Neanderthals – bone flutes, ivory
sculptures, and burial ceremonies
– Paintings…
– Figure 15.16 Paleolithic burial (p. 277)
– Figure 15.17 The sophistication of Cro-Magnon people (p.
278)
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Quick Definition Slide
•
•
•
•
•
•
•
•
The Animal …Kingdom
sharing with all other members of this group the need to feed on organic
matter (unlike plants which can create energy using light and minerals)
The Chordate (or vertebrate) … Phylum
sharing with all other members of this group of animals, a back bone with a
hollow nerve chord
The Mammal … Class
sharing with all other members of this group of vertebrates, the ability to feed
their offspring on milk and having a body covering which includes fur
The Primate … Order
Sharing with all other members of this group of mammals, a thumb that can
be opposed to the other digits, binocular vision and various more broadly
defined characteristics (including high intelligence, relatively long maturation
period for the young, dental similarities, tendency for complex social
organization, and generally bearing one or two young)
The Lemuridae … Family
Sharing with other members of this group of primates, a slightly longer nose,
smaller brain, long slender limbs, a tail, more specific dental features
including the grooming comb formed by the lower incisor and canine teeth
The Lemur … Genus
Sharing with other members of this group of lemurs, scent marking methods,
vocalizations, aspects of social structure and overall body shape
The Ring-tailed Lemur … Species
A species is the primary unit of biological classification or taxonomy. Species
members share a basic genetic similarity and can interbreed and produce
viable or fertile offspring
.
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How Did Humans Evolve?
• Cro-Magnons and Neanderthals Lived
Side by Side
• For about 50,000 years
• Some think interbreeding happened
• (“Clan of the Cave Bear” series?)
• Others think not and that the CroMagnons simply overran and displaced
the less-well-adapted Neanderthals
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Chapter 16
• The Diversity of Life
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How Are Organisms Named
and Classified?
• A random sample of water from the
Sargasso Sea yielded evidence of 1800
microscopic species – mostly unknown
species! We have a LOT to learn still.
• We know of 5000 species of bacteria (only a
fraction of what is out there)
• Table 16.1 Classification of Selected
Organisms, Reflecting Their Degree of
Relatedness (p. 284)
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Quick Definition Slide Repeat
•
•
•
•
•
•
•
•
The Animal …Kingdom
sharing with all other members of this group the need to feed on organic
matter (unlike plants which can create energy using light and minerals)
The Chordate (or vertebrate) … Phylum
sharing with all other members of this group of animals, a back bone with a
hollow nerve chord
The Mammal … Class
sharing with all other members of this group of vertebrates, the ability to feed
their offspring on milk and having a body covering which includes fur
The Primate … Order
Sharing with all other members of this group of mammals, a thumb that can
be opposed to the other digits, binocular vision and various more broadly
defined characteristics (including high intelligence, relatively long maturation
period for the young, dental similarities, tendency for complex social
organization, and generally bearing one or two young)
The Lemuridae … Family
Sharing with other members of this group of primates, a slightly longer nose,
smaller brain, long slender limbs, a tail, more specific dental features
including the grooming comb formed by the lower incisor and canine teeth
The Lemur … Genus
Sharing with other members of this group of lemurs, scent marking methods,
vocalizations, aspects of social structure and overall body shape
The Ring-tailed Lemur … Species
A species is the primary unit of biological classification or taxonomy. Species
members share a basic genetic similarity and can interbreed and produce
viable or fertile offspring
.
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How Are Organisms Named
and Classified?
• Each Species Has a Unique, Two-Part
Name
– Based on species and genus
– e.g. genus Sialia (blue-bird)
•
•
•
•
eastern bluebird (sialia sialis)
western bluebird (Sialia mexicana)
mountain bluebird (Sialia currucoides)
All three normall do NOT interbreed
– Figure 16.1 Three species of bluebird (p. 285)
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How Are Organisms Named
and Classified?
• Classification Originated As a Hierarchy of Categories
–
–
–
–
–
Aristotle first tried to name things in a logical fashion
He classified 500 organisms in 11 categories
Forms the basis of today’s systems
Carl von Linne – laid the groundwork for the modern system
Charles Darwin – supplied the connectedness that made the system make
sense
• Biologists Identify Features That Reveal Evolutionary Relationships
– Similar features = a common ancestor (vs. convergent evolution)
• Anatomy Plays a Key Role in Classification
– Remember the ‘hand structure’ inside many mammels
– Figure 16.2 Microscopic structures may be used to classify organisms (p.
285)
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‘teeth’ on a snails
tongue
bristles ona marine worm
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pollen grain shapes
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How Are Organisms Named
and Classified?
• Molecular Similarities Are Also Useful
for Classification
– Molecular genetics only possible recently
– DNA/genotype
– Chromosome structures
• Chimpanzees and humans are extremely
similar
• Cats and humans are also extremely similar
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What Are the Domains of
Life?
• The Five-Kingdom System Improved Classification
– prokaryotes
– eukaryotes  Plantae, Fungi, and Animalia
• A Three-Domain System More Accurately Reflects
Life’s History
– Prokaryotes  bacteria and archaea (VERY different)
– Figure 16.3 Two domains of prokaryotic organisms (p.
286)
– Figure 16.4 The tree of life (p. 287)
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BACTERIA
ARCHAEA
EUKARYA
animals
fungi
plants
protists
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What Are the Domains of Life?
• Kingdom-Level Classification Remains
Unsettled
– about 15 kingdoms among bacteria
– 3 or so kingdoms of archaea
– single celled eukaryotes – formerly called
protista
– In transition currently.
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Bacteria and Archaea
• Two of life’s three domains – Bacteria and
Archaea = prokaryotes
• Single celled organisms, lack organelles, no
nucleus, chloroplasts or mitochondria
• Very small (.2 to 10 micrometers eukaryotic cells = 10 to 100 micrometers)
• The largest bacterium = 700 micrometers =
big enough to see…
• Tree of Life: Bacteria and Archaea (p. 287)
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BACTERIA
ARCHAEA EUKARYA
animals fungi
plants
protists
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Bacteria and Archaea
• Bacteria and Archaea Are Fundamentally Different
–
–
–
–
Different cell wall structure (chemically)
Different RNA, plasma membranes, ribosomes etc.
Easy to tell bacteria from archaea
Classification of Prokaryotes within Each Domain Is
Difficult
– New discoveries  definitions will keep changing
• Prokaryotes Differ in Shape and Structure
– Figure 16.5 Three common prokaryote shapes (p. 288)
– Figure 16.6 The prokaryote flagellum (p. 288)
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spherical bacteria
rod like archaea
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corckscrep shaped
bacteria
Prokaryote – uses flagella to move toward
favorable environments
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Bacteria and Archaea
– Many Bacteria Form Films on Surfaces
•
•
•
•
Biofilm – resistant to attack
Plaque on teeth is an example
Contact lenses, surgical sutures, medical equipment
Contribute to ear infections, tooth decay
– Protective Endospores Allow Some Bacteria to
Withstand Adverse Conditions
• Stops metabolic activity until conditions are more
favorable
• Some can withstand boiling for an hour!
• Preserved spores in a rock for 250 million years
• Anthrax is another example
• Figure 16.7 Spores protect some bacteria (p. 289)
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endospore
bacterium
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Bacteria and Archaea
• Prokaryotes Reproduce by Binary
Fission
– Simple division
– Can divide once each 20 minutes
– Can yield sextillions (1021) offspring in a
day
– = Rapid mutations possible
– Figure 16.8 Reproduction in prokaryotes
(p. 289)
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Bacteria and Archaea
• Prokaryotes Are Specialized for Specific
Habitats
– Prokaryotes inhabit virtually every habitat and
extreme environment possible
– Bacteria found ‘alive’ in the gut of a mammoth
buried in a peat bog for 11,000 years
– Icy/salty conditions
– High pressure conditions
– Even hot springs and volcanic vents (e.g. 223 F)
– Figure 16.9 Some prokaryotes thrive in extreme
conditions (p. 289)
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Bacteria and Archaea
• Prokaryotes Exhibit Diverse Metabolisms
– Can be anaerobic (no oxygen required for
metabolism)
– Tetanus bacteria – killed by oxygen
– Can live on sugars, fats, proteins AND petroleum,
methane, solvents like benzene and toluene.
They can metabolize inorganic substances like
hydrogen, sulfur, ammonia, iron and nitrite.
Some even can photosynthesize.
– No photosynthetic archaea are known.
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Important prokaryotes
• Prokaryotes Perform Functions Important
to Other Organisms
– Help animals digest vegetable matter
(cows/grass, termites/wood)
– Prokaryotes Capture the Nitrogen Needed
by Plants – nitrogen fixing
– Prokaryotes Are Nature’s Recyclers –
biodegradable substances rely on
prokaryotes to do the work
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Bad prokaryotes
• Some Bacteria Pose a Threat to Human Health
– Some Anaerobic Bacteria Produce Dangerous Poisons –
pathogens
• botulism (anaerobic bacteria)
• tetanus (anaerobic bacteria)
– Humans Battle Bacterial Diseases Old and New
• Bubonic plague (“Black Death”) - killed 100 million people during the
mid 1500’s
– 1/3rd or more of the population died in places in the world
• Lyme disease – new (1975 discovery) – spiral shaped bacteria
• Tuberculosis – almost eliminated in the world is coming back
• Cholera – water-transmitted – can still re-emerge where raw sewage
contaminates drinking water
– Some Common Bacterial Species Can Be Harmful
• Streptococcus pneumoniae – common and causes different diseases
– Pneumonia
– Flesh eating – 15% of victims die
– E. coli – common in the digestive track – can come from tainted meat
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But don’t panic…
– Most Bacteria Are Harmless
• Bacteria in our intestines help produce vitamin K
• Keep yeast infections at bay
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Protists
•
•
•
•
The third domain = Eukarya
Fungi, Plantae, Animalia (later)
And protists
Tree of Life: Protists (p. 293)
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BACTERIA
EUKARYA
ARCHAEA
animals fungi
plants
protists
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Protists
• Most Protists Are Single Celled
– And very tiny
• The Chromists Include Photosynthetic
(algae) and Nonphotosynthetic Organisms
(protozoa)
– Diatoms Encase Themselves within Glassy Walls
• Ocean dwelling – phytoplankton
• 70% of all the photosynthesis on the planet and most of
the Oxygen we breath
• Figure 16.10 Some representative diatoms (p. 293)
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Protists
– Brown Algae Dominate in Cool Coastal
Waters
• Most are single celled, but some conglomerate
into longer structures – known as seaweeds
• No roots, shoots, or seeds
• Near shore, further out at sea, some gas filled
to float, some grow to 325 feet (100 meters) in
height – may grow 6 inches a day
• Figure 16.11 Brown algae (p. 294)
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Protists
• The Alveolates Include Parasites,
Predators, and Phytoplankton
– Dinoflagellates Swim by Means of Two
Whiplike Flagella
• Figure 16.12 Dinoflagellates (p. 294)
– Some live inside corals, clams and other protists and
provide nutrients/energy to hosts
• Figure 16.13 Some grow so fast in the right
conditions, they color the sea … A red tide (p.
295)
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Protists
– Apicomplexans Are Parasitic and Have No Means
of Locomotion
•
•
•
•
•
Live inside bodies and/or cells
For infectious spores
Can be passed through food, water, insect bites
Plasmodium = parasite  malaria
Explosive growth in liver and red blood cells = spores
and often death
– Ciliates Are the Most Complex of the Alveolates
• Peak of unicellular complexity
• Usually localized cilia – short hair like outgrowths for
locomotion
• Responds well to it’s environment… can hunt and eat
• Figure 16.14 A microscopic predator (p. 295)
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Protists
• Slime Molds Are Decomposers That Inhabit
the Forest Floor
– Either eating or reproducing (fruiting body)
– No real cell walls…engulfs leaves and rotting
matter – using energy
– Acellular Slime Molds Form a Multinucleate Mass
of Cytoplasm
– Forms spores when things dry out…
• Figure 16.15 The acellular slime mold Physarum (p.
296)
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Protists
• Various Protists Move by Means of
Pseudopods
– Figure 16.16 Amoebas (p. 296)
• Can cause dysentery – multiplies on intestinal wall
– Figure 16.17 Foraminiferans and radiolarians (p.
297)
• Marine protists  make beautiful shells!
• = Limestone deposits
• Got rid of our CO2 atmosphere from early on…
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pseudopod
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pseudopod
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pseudopod
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pseudopod
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Protists
• Green Algae Live Mostly in Ponds and
Lakes
– Multicellular and unicellular species
– Long chains/filaments
– Figure 16.18 A green alga (p. 297)
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Fungi
• Tree of Life: Fungi (p. 297)
• Figure 16.19 The filamentous body of a
fungus (p. 298)
• Mycelium – body of a fungi
• Interwoven threadlike filaments are
called hyphae
• (Gross unless on a Pizza)
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BACTERIA
EUKARYA
ARCHAEA
animals fungi
plants
protists
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hyphae
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hyphae
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Fungi
• Fungi Obtain Their Nutrients from Other
Organisms
– Feed on dead bodies
– Some feed on living beings
– They don’t digest, they secret enzymes that digest
outside their bodies
– Filaments one cell thick can penetrate deep into
objects and obtain nutrients
• Most Fungi Can Reproduce Both Sexually
and Asexually
– Figure 16.20 Some fungi can eject spores (p. 298)
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Fungi
• Fungi Attack Plants That Are Important to
People
– Fungi attacked American elms and American
chestnuts (most gone now)
– Dutch Elm disease also a fungi (most Elm streets
don’t have Elm trees anymore)
– Figure 16.21 Corn smut (p. 299)
– But they aren’t always harmful, they can attack
pests as well…
– Figure 16.22 A helpful fungal parasite (p. 299)
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Bad Fungi
• Fungi Cause Human Diseases
– Some attack human skin
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•
•
•
•
•
Athletes foot
Jock itch
Toenail fungus
Ringworm
Vaginal infections caused by yeast
Valley Fever and histoplasmosis (lung diseases or around
the heart)
• Fungi Can Produce Toxins
– Peanuts = aflatoxins from Aspergillus
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Good Fungi
• Many Antibiotics Are Derived from Fungi
– Penicillin
– Cyclosporine
• Fungi Make Important Contributions to
Gastronomy
– Mushrooms
– Truffles
– Roquefort, Camembert, Stilton, Gorgonzola cheeses get
their flavor from molds
– Figure 16.23 A delicious fungus (p. 299)
– Yeasts are very important for beer, bread, wine…
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Fungi
– Wine and Beer Are Made Using Yeasts
• WIDE variety of flavors
• Fermentation (anaerobic) important
– Yeast extracts energy from sugar and emit carbon dioxide
and/or ethyl alcohol as a byproduct
– The alcohol eventually kills the yeast and fermentation
ends
– If the yeast dies early = sweet wines, if the sugar is used
up first = dry wines
– In beer, sprouted grains are needed (germination
converts carbohydrates to sugars the yeast can use)
» Alcohol AND carbonation important
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Show me the bread
• Yeasts Make Bread Rise
– Carbon dioxide is the important by-product
– The alcohol evaporates during baking
– Hurray for yeasts.
• Fungi Play a Crucial Ecological Role
– They are Earth’s undertakers
– Nutrients get back to the environment from
dead things because of them
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Plants
• Bryophytes = nonvascular plants
– Need moist environments
• Vascular plants
– Can live in drier environments
• Tree of Life: Plants (p. 300)
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BACTERIA
EUKARYA
ARCHAEA
animals fungi
plants
protists
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Plants - Bryophytes
• Bryophytes retain some characteristics
of their algal ancestors.
• Do have roots that bring water up, but
not through vascular tubes
• Body size is limited
• Bryophytes Lack Conducting Structures
– Figure 16.24 Bryophytes (p. 300)
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Plants
– The Reproductive Structures of Bryophytes Are Protected
• Gametes are contained inside the plant to keep them moist
• Sometimes rain is needed to help sperm meet the eggs
• The Vascular Plants Have Conducting Vessels
That Also Provide Support
– Vascular systems let the plants grow larger…so they need
to hold themselves up
• The Seedless Vascular Plants Include the Club
Mosses, Horsetails, and Ferns
– Seedless vascular plants once dominated the planet
– Now are most of the coal we dig up
– Figure 16.25 Seedless vascular plants (p. 301)
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Club Moss
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giant
horsetail
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Deer Fern
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Plants
• The Seed Plants Dominate the Land, Aided by Two
Important Adaptations: Pollen and Seeds
– Fully adapted to life on dry land (don’t need water for sperm
to swim to seeds/eggs)
– Like animals, seeds have an embryonic plant
• Gymnosperms Are Nonflowering Seed Plants
–
–
–
–
Evolved earlier than flowering plants
Conifers are members of these
Developed anti-freeze for cold climates
Figure 16.26 Two uncommon gymnosperms (p. 302)
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Ginkgo – foul smell when ripe
Cycad
– common
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in age of dinosaurs
Plants
• Angiosperms Are Flowering Seed Plants
– Have dominated on the Earth for 100 million
years
– Came later than gymnosperms
– 230,000 known species
– Include duckweed to towering eucalyptus trees
– Figure 16.27 Flowering plants (p. 303)
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Duck weed
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Largest = Eucalyptus
trees
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birch
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Plants
– Flowers Attract Pollinators
• Animals benefit eating nutrient rich pollen and
carry it to female plants
– Fruits Encourage Seed Dispersal
• Animals eat fleshy parts and drop seeds
elsewhere
• Burrs catch on fur/socks/pants and carry seeds
away
– Broad Leaves Capture More Sunlight
• And store water in drier or darker climates
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Animals
•
•
•
•
•
•
Are Multicellular
Get energy by consuming other organisms
Typically reproduces sexually
Animal cells lack a cell wall (wood like)
Can move around
Can respond rapidly to stimuli/changes in
the environment
• Tree of Life: Animals (p. 304)
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BACTERIA
EUKARYA
ARCHAEA
animals fungi
plants
protists
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Animals
• Most Animals Lack Backbones
– Insects and worms
– We look at vertebrates and invertebrates as a simple way
to divide things up
• Sponges Have a Simple Body Plan
–
–
–
–
–
(poor Spongebob)
almost like groups of single cells
nor organs, just pores
largest can grow to 3 feet high
some have internal skeletons composed of calcium
carbonate (chalk) or silica (glass)
– Most often found in salt water environments
– Figure 16.28 Sponges (p. 305)
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Animals
• Cnidarians Are Well-Armed Predators
– jellyfish, sea anemones, corals and
hydrozoans
– Tremendous variety
– Can shoot out poisonous or sticky filaments
into prey
– Some jellyfish are deadly to humans
– Figure 16.29 Cnidarians (p. 305)
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Animals
• Annelids Are Composed of Identical
Segments
– Segmented worms
– Externally look like segments, internally
each segment = a copy of the others
(nervous system, muscles, excretory
structures)
– Includes leeches
– Figure 16.30 Annelids (p. 306)
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Animals
• Arthropods Are the Dominant Animals on Earth
–
–
–
–
They outnumber everything
1 million species known
insects, arachnids, crustaceans
Exoskeletons (must be shed/molted as it grows)
• Soft shelled crabs are those caught right after molting
–
–
–
–
Quick movement possible
Flight
Webs (spiders)
Insects Are the Only Flying Invertebrates
• Larva stage – maggots, caterpellar
• Figure 16.31 Insects (p. 307)
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aphid
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Hercules beetle (with
hornsmale)
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June beetle
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Locust
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Caterpillars – larval forms of
butterflies
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Prenticeor
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Inc.
Animals
– Most Arachnids Are Predatory Meat Eaters
•
•
•
•
•
Spiders, mites, ticks and scorpions
They first immobilize with venom
Then inject digestive enzymes
Suck the soup out
Most ‘see’ with multiple eyes and can react
quickly to movement
• Figure 16.32 Arachnids (p. 308)
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Animals
– Most Crustaceans Are Aquatic
• Crabs, crayfish, lobster, shrimp, and barnacles
• Only class of arthropods whose members live
primarily in the water
• The Japanese crab has legs spanning nearly
12 feet (4 meters)
• Figure 16.33 Crustaceans (p. 308)
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water flea
hermit
crab
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sowbug
goose-neck barnacle
Animals
• Most Mollusks Have Shells
– Snails, slugs, clams, octopuses …
– Gastropods Are One-Footed Crawlers
• Snails and slugs
• Shells protect them
• Bright colors and bad tastes as well
• Figure 16.34 Gastropod mollusks (p. 309)
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More Animals
– Bivalves Are Filter Feeders
• Scallops, oysters, mussels, clams
• Important members of near shore marine
communities
• Two shells connected by a hinge
• Gills used for breathing and feeding
• Don’t move much- anchor by a ‘foot’
• Figure 16.35 Bivalve mollusks (p. 309)
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Animals
– Cephalopods Are Marine Predators
•
•
•
•
•
•
•
•
•
Octopuses, nautiluses, cuttlefish, squids
Largest invertebrate = the giant squid
Are predatory carnivores
All marine creatures
Tentacles grab, immobilize, inject paralyzing venom,
then tear apart with beaklike jaw
Highly developed brains and sensory systems
Their eye rivals ours in complexity
In the lab, the octopus can learn shapes that tell it what
jar to open for food it wants
Figure 16.36 Cephalopod mollusks (p. 310)
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Animals
• The Chordates Include Both Invertebrates
and Vertebrates
– We share the chordate phylum not only with birds,
apes, but with the tunicates (sea squirts)
– Notochord (stiff body length anchor for muscles)
– Nerve cord
– Pharyngeal gill slits (like the pharynx – back of
our mouth)
– Postanal tail (body beyond the anus)
– The Invertebrate Chordates Live in the Seas
• Figure 16.37 An invertebrate chordate (p. 311)
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Animals
– Vertebrates Have a Backbone
• Bony fishes (p. 311)
– most vertebrates are located in the ocean
– 17,000 species have been identified
• Amphibians (p. 312)
– both aquatic and terrestrial
– 3 chambered heart (fish = 2 chambered heart)
circulates blood efficiently, lungs replace gills in adults
– Lungs not as efficient as mammals – skin also
breathes
– Some undergo metamorphosis – tadpoles  frogs
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Animals you’ve heard of
• Reptiles (p. 312)
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–
–
–
tough scaly skin, resists water loss
internal fertilization (male deposits sperm inside females)
shelled eggs
body temperature varies with environment
• Birds (p. 314)
–
–
–
–
–
closely related to reptiles
scales still on legs
light and good for flight
some reptile bones missing or fused to save weight
only one ovary and reproductive organs shrink when not
needed
– can keep body temperature high
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You!
• Mammals (p. 315)
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Evolved hair
first appeared about 250 mya
legs designed for running
fast and aglie
bat, mole, impala, whale, seal, monkey, cheetah, humans
Mammals = females have mammary glands = milk-producing to suckle
young
mammal bodies sweat, have scent, oil-producing glands (not found in
other vertebrates)
long period of parental care
highly developed brain
can adapt via rapid changes in behavior and response to
environmental changes
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deep sea angler
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seahorse
moray eel
coelacanth – thought extinct
anphibians
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reptiles
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Next Time
• Chapters 27-30
• Quiz over this and next lecture
• Ecology in terms of populations and
community interactions
• Components of ecosystems and the
biosphere
• Ecosystem dynamics and humans
• Current environment issues relevant to this
biology course
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