Transcript Intro Bio Chapter 14-15 Fall 2015

Chapter 14
How Biological Diversity Evolves
PowerPoint® Lectures for
Campbell Essential Biology, Fifth Edition, and
Campbell Essential Biology with Physiology,
Fourth Edition
– Eric J. Simon, Jean L. Dickey, and Jane B. Reece
Lectures by Edward J. Zalisko
© 2013 Pearson Education, Inc.
Biology and Society:
The Sixth Mass Extinction
• Over the past 540 million years, the fossil record
reveals five periods of extinction when 50–90% of
living species suddenly died out.
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Biology and Society:
The Sixth Mass Extinction
• Our current rate of extinction, over the past 400
years, indicates that we may be living in, and
contributing to, the sixth mass extinction period.
• Mass extinctions pave the way for the evolution of
new and diverse forms, but it takes millions of
years for Earth to recover.
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THE ORIGIN OF SPECIES
• When Darwin visited the Galápagos Islands, he
realized that he was visiting a place of origins.
– Although the volcanic islands were geologically
young, they were home to many plants and
animals known nowhere else in the world.
– Darwin thought it unlikely that all of these species
could have been among the original colonists of
the islands.
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Figure 14.1
PATTERNS OF EVOLUTION
THE ORIGIN OF SPECIES
• In the 150 years since the publication of Darwin’s
book On the Origin of Species by Means of Natural
Selection, new discoveries and technological
advances have given scientists a wealth of new
information about the evolution of life.
• The diversity of life evolved through speciation,
the process in which one species splits into two or
more species.
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What Is a Species?
• Species is a Latin word meaning
– “kind” or
– “appearance.”
• The biological species concept defines a
species as “A group of populations whose
members have the potential to interbreed with one
another in nature to produce fertile offspring.”
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Figure 14.2
Similarity between different species
Diversity within one species
What Is a Species?
• Some other definitions of species are based on
– measurable physical traits,
– the use of ecological resources, or
– unique adaptations to particular roles in a biological
community.
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Reproductive Barriers between Species
• Prezygotic barriers prevent mating or fertilization
between species.
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Reproductive Barriers between Species
• Prezygotic barriers include
– temporal isolation,
– habitat isolation,
– behavioral isolation,
– mechanical isolation, and
– gametic isolation.
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Figure 14.4a
Temporal Isolation
Skunk species that mate at different times
Figure 14.4b
Habitat Isolation
Garter snake species from different habitats
Figure 14.4c
Behavioral Isolation
Mating ritual of blue-footed
boobies
Figure 14.4d
Mechanical Isolation
Snail species whose genital
openings cannot align
Figure 14.4e
Gametic Isolation
Sea urchin species whose
gametes cannot fuse
Reproductive Barriers between Species
• Postzygotic barriers operate if
– interspecies mating occurs and
– hybrid zygotes form.
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Reproductive Barriers between Species
• Postzygotic barriers include
– reduced hybrid viability,
– reduced hybrid fertility, and
– hybrid breakdown.
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Figure 14.5a
Reduced Hybrid Viability
Frail hybrid salamander
offspring
Figure 14.5b
Reduced Hybrid Fertility
Horse
Donkey
Mule
Mule (sterile hybrid of
horse and donkey)
Figure 14.5c
Hybrid Breakdown
Sterile next-generation
rice hybrid
Mechanisms of Speciation
• A key event in the potential origin of a species
occurs when a population is somehow cut off from
other populations of the parent species.
• Species can form by
– allopatric speciation, due to geographic
isolation, or
– sympatric speciation, without geographic
isolation.
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Figure 14.6
Allopatric speciation
Sympatric speciation
Figure 14.7
Ammospermophilus
harrisii
Ammospermophilus
leucurus
Sympatric Speciation
• Sympatric speciation occurs in populations that live
in the same geographic area.
• An accident during cell division that results in an
extra set of chromosomes is a common route to
sympatric speciation in plants.
• Many polyploid species arise from the hybridization
of two parent species.
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Sympatric Speciation
• Many domesticated plants are the result of
sympatric speciation, including
– oats,
– potatoes,
– bananas,
– peanuts,
– apples,
– coffee, and
– wheat.
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Figure 14.9a
EARTH HISTORY AND MACROEVOLUTION
• Macroevolution is closely tied to the history of
Earth.
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Geologic Time and the Fossil Record
• The fossil record is
– the sequence in which fossils appear in rock strata
and
– an archive of macroevolution.
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Figure 14.14
A researcher
excavating a
fossilized
dinosaur
skeleton from
sandstone
A sedimentary fossil formed
by minerals replacing the
organic matter of a tree
A 45-million-year-old
insect embedded
in amber
Trace fossils: footprints, burrows,
or other remnants of an ancient
organism’s behavior
Tusks of a 23,000-year-old mammoth
discovered in Siberian ice
Table 14.1
Table 14.1
The Geologic Time Scale
Geologic
Time
Period
Quaternary
Epoch
Age (millions
of years ago)
Recent
Pleistocene
Pliocene
0.01
1.8
5
Miocene
Cenozoic
era
23
Tertiary
Oligocene
34
Eocene
56
Paleocene
65
Cretaceous
Mesozoic
era
145
Some Important Events in the History of Life
Historical time
Cenozoic
Ice ages; humans appear
Mesozoic
Origin of genus Homo
Continued speciation of mammals and
angiosperms
Paleozoic
Origins of many primate groups,
including apes
Angiosperm dominance increases; origins of most
living mammalian orders
Major speciation of mammals, birds,
and pollinating insects
Flowering plants (angiosperms) appear; many groups of
organisms, including most dinosaur lineages, become
extinct at end of period (Cretaceous extinctions)
Gymnosperms continue as dominant plants;
dinosaurs become dominant
Jurassic
200
Triassic
251
Permian
299
Cone-bearing plants (gymnosperms) dominate landscape;
speciation of dinosaurs, early mammals, and birds
Extinction of many marine and terrestrial organisms
(Permian extinctions); speciation of reptiles; origins of
mammal-like reptiles and most living orders of insects
Extensive forests of vascular plants; first seed
plants; origin of reptiles; amphibians become dominant
Carboniferous
359
Paleozoic
era
Diversification of bony fishes;
first amphibians and insects
Devonian
416
Silurian
Early vascular plants dominate land
444
Ordovician
Cambrian
488
Marine algae are abundant; colonization of land by
diverse fungi, plants, and animals
Origin of most living animal phyla (Cambrian explosion)
542
Precambrian
Relative
Time Span
600
Diverse algae and soft-bodied invertebrate animals appear
635
Oldest animal fossils
2,100
Oldest eukaryotic fossils
2,700
Oxygen begins accumulating in atmosphere
3,500
Oldest fossils known (prokaryotes)
4,600
Approximate time of origin of Earth
Precambrian
Geologic Time and the Fossil Record
• Radiometric dating
– is the most common method for dating fossils,
– is based on the decay of radioactive isotopes, and
– helped establish the geologic time scale.
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Radioactive decay
of carbon-14
Carbon-14 radioactivity
(as % of living organism’s
C-14 to C-12 ratio)
Figure 14.15
100
75
50
25
0
0
5.6 11.2 16.8 22.4 28.0 33.6 39.2 44.8 50.4
Time (thousands of years)
How
carbon-14
dating is
used to
determine
the vintage
of a
fossilized
clam shell
Carbon-14 in shell
Carbon-14 is taken up
by the clam in trace
quantities, along with
much larger quantities
of carbon-12.
After the clam dies,
carbon-14 amounts
decline due to
radioactive decay.
Measuring the ratio of
carbon-14 to carbon-12
reveals how many halflife reductions have
occurred since the
clam’s death.
Plate Tectonics and Macroevolution
• The continents are not locked in place.
– Continents drift about Earth’s surface on plates of
crust floating on a flexible layer of hot, underlying
material called the mantle.
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Plate Tectonics and Macroevolution
• Japan sits atop four different plates.
– A tsunami, caused by an earthquake off the coast
of Japan, resulted in the disaster of March 2011.
– Frequent earthquakes occur as the plates move
and bump against each other.
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Figure 14.16
Plate Tectonics and Macroevolution
• About 250 million years ago,
– plate movements formed the supercontinent
Pangaea,
– the total amount of shoreline was reduced,
– ocean basins increased in depth,
– sea levels dropped,
– the dry continental interior increased in size, and
– many extinctions occurred.
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Pangaea is formed.
Mesozoic
Paleozoic
Pangaea splits into
Laurasia and Gondwana.
251 million years ago
135
65
India collides with Eurasia.
Cenozoic
Present
Figure 14.17
Mass Extinctions and Explosive
Diversifications of Life
• The fossil record reveals that five mass extinctions
have occurred over the last 540 million years.
• The Permian mass extinction
– occurred at about the time the merging continents
formed Pangaea (250 million years ago) and
– claimed about 96% of marine species.
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Mass Extinctions and Explosive
Diversifications of Life
• The Cretaceous extinction
– occurred at the end of the Cretaceous period,
about 65 million years ago,
– included the extinction of all the dinosaurs except
birds, and
– permitted the rise of mammals.
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The Process of Science:
Did a Meteor Kill the Dinosaurs?
• The fossil record reveals that five mass extinctions
have occurred over the last 540 million years.
• In each of these events, 50% or more of Earth’s
species died out.
• Of all the mass extinctions, those marking the ends
of the Permian and Cretaceous periods have been
the most intensively studied.
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The Process of Science:
Did a Meteor Kill the Dinosaurs?
• Observation: About 65 million years ago, the fossil
record shows that
– the climate cooled,
– seas were receding,
– many plant species died out,
– dinosaurs (except birds) became extinct, and
– a thin layer of clay rich in iridium was deposited.
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The Process of Science:
Did a Meteor Kill the Dinosaurs?
• Question: Is the iridium layer the result of fallout
from a huge cloud of dust that billowed into the
atmosphere when a large meteor or asteroid hit
Earth?
• Hypothesis: The mass extinction 65 million years
ago was caused by the impact of an extraterrestrial
object.
• Prediction: A huge impact crater of the right age
should be found somewhere on Earth’s surface.
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The Process of Science:
Did a Meteor Kill the Dinosaurs?
• Results: Near the Yucatán Peninsula, a huge
impact crater was found that
– dated from the predicted time,
– was about the right size, and
– was capable of creating a cloud that could have
blocked enough sunlight to change the Earth’s
climate for months.
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Figure 14.18-3
Chicxulub crater
CLASSIFYING THE DIVERSITY OF LIFE
• Taxonomy is the
– identification,
– naming, and
– classification of species.
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Some Basics of Taxonomy
• Carolus Linnaeus (1707–1778) proposed the
current taxonomic system based upon a
– two-part name for each species and
– hierarchical classification of species into broader
groups of organisms.
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Naming Species
• Each species is assigned a two-part Latinized
name or binomial, consisting of
– the genus and
– a name unique for each species.
• The scientific name for humans is Homo sapiens,
– a two part name, italicized,
– given a Latin ending, and
– with the first letter of the genus capitalized.
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Hierarchical Classification
• Species that are closely related are placed into the
same genus.
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Figure 14.19
Leopard
(Panthera pardus)
Lion
(Panthera leo)
Tiger
(Panthera tigris)
Jaguar (Panthera onca)
Hierarchical Classification
• The taxonomic hierarchy extends to progressively
broader categories of classification, from genus to
– family,
– order,
– class,
– phylum,
– kingdom, and
– domain.
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Figure 14.20
Leopard
(Panthera pardus)
Species
Panthera
pardus
Genus
Panthera
Family
Felidae
Order
Carnivora
Class
Mammalia
Phylum
Chordata
Kingdom
Animalia
Domain
Eukarya
Classification: A Work in Progress
• In the mid-1900s, the two-kingdom system was
replaced by a five-kingdom system that
– placed all prokaryotes in one kingdom and
– divided the eukaryotes among four other
kingdoms.
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Classification: A Work in Progress
• In the late 1900s, molecular studies and cladistics
led to the development of a three-domain system,
recognizing
– two domains of prokaryotes (Bacteria and
Archaea) and
– one domain of eukaryotes (Eukarya).
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Figure 14.25
Domain Bacteria
Earliest
organisms
Domain Archaea
The protists
(multiple
kingdoms)
Kingdom
Plantae
Domain Eukarya
Kingdom
Fungi
Kingdom
Animalia
Figure 14.UN01
Zygote
Gametes
Prezygotic barriers
• Temporal isolation
• Habitat isolation
• Behavioral isolation
• Mechanical isolation
• Gametic isolation
Postzygotic barriers
• Reduced hybrid viability
• Reduced hybrid fertility
• Hybrid breakdown
Viable,
fertile
offspring
Figure 14.UN02
Allopatric speciation
(occurs after
geographic isolation)
Parent
population
Sympatric speciation
(occurs without
geographic isolation)
Figure 14.UN03
Bacteria
Earliest
organisms
Archaea
Eukarya
Chapter 15
The Evolution of Microbial Life
PowerPoint® Lectures for
Campbell Essential Biology, Fifth Edition, and
Campbell Essential Biology with Physiology,
Fourth Edition
– Eric J. Simon, Jean L. Dickey, and Jane B. Reece
Lectures by Edward J. Zalisko
© 2013 Pearson Education, Inc.
MAJOR EPISODES IN THE HISTORY OF
LIFE
• Earth was formed about 4.6 billion years ago.
• Prokaryotes
– evolved by about 3.5 billion years ago,
– began oxygen production about 2.7 billion years
ago,
– lived alone for more than a billion years, and
– continue in great abundance today.
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MAJOR EPISODES IN THE HISTORY OF
LIFE
• Single-celled eukaryotes first evolved about 2.1
billion years ago.
• Multicellular eukaryotes first evolved at least 1.2
billion years ago.
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MAJOR EPISODES IN THE HISTORY OF
LIFE
• What if we use a clock analogy to tick down all of
the major events in the history of life on Earth?
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Figure 15.2
Humans
Origin of solar
system and Earth
0
1
4
2
3
THE ORIGIN OF LIFE
• We may never know for sure how life on Earth
began.
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Resolving the Biogenesis Paradox
• All life today arises by the reproduction of
preexisting life, or biogenesis.
• If this is true, how could the first organisms arise?
• From the time of the ancient Greeks until well into
the 1800s, it was commonly believed that life
regularly arises from nonliving matter, an idea
called spontaneous generation.
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Resolving the Biogenesis Paradox
• Today, most biologists think it is possible that life
on early Earth evolved from simple cells produced
by
– chemical and
– physical processes.
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Figure 15.3
From Chemical Evolution to Darwinian Evolution
• Over millions of years
– natural selection favored the most efficient precells and
– the first prokaryotic cells evolved.
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PROKARYOTES
• Prokaryotes lived and evolved all alone
on Earth for about 2 billion years.
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They’re Everywhere!
• Prokaryotes
– are found wherever there is life,
– have a collective biomass that is at least ten times
that of all eukaryotes,
– thrive in habitats too cold, too hot, too salty, too
acidic, or too alkaline for any eukaryote,
– cause about half of all human diseases, and
– are more commonly benign or beneficial.
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Figure 15.6
They’re Everywhere!
• Compared to eukaryotes, prokaryotes are
– much more abundant and
– typically much smaller.
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Colorized SEM
Figure 15.7
The Structure and Function of Prokaryotes
• Prokaryotic cells
– lack a membrane-enclosed nucleus,
– lack other membrane-enclosed organelles,
– typically have cell walls exterior to their plasma
membranes, but
– display an enormous range of diversity.
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Figure 4.4
Plasma membrane
Cell wall
Capsule
Prokaryotic
flagellum
Ribosomes
Nucleoid
Colorized TEM
Pili
Figure 4.5
Ribosomes
Cytoskeleton
Not in most
plant cells
Centriole
Lysosome
Plasma
membrane
Nucleus
Mitochondrion
Rough endoplasmic
reticulum (ER)
Smooth
endoplasmic
reticulum (ER)
Golgi apparatus
Idealized animal cell
Cytoskeleton
Mitochondrion
Central vacuole
Cell wall
Chloroplast
Nucleus
Not in animal cells
Rough endoplasmic
reticulum (ER)
Ribosomes
Plasma
membrane
Smooth
endoplasmic
reticulum (ER)
Idealized plant cell
Channels between cells
Golgi apparatus
Prokaryotic Forms
• The three most common shapes of prokaryotes
are
1. spherical (cocci),
2. rod-shaped (bacilli), and
3. spiral or curved.
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Figure 15.8
SHAPES OF PROKARYOTIC CELLS
Rod-shaped (bacilli)
Colorized TEM
Spiral
Colorized SEM
Colorized SEM
Spherical (cocci)
Prokaryotic Forms
• All prokaryotes are unicellular.
• Some species
– exist as groups of two or more cells,
– exhibit a simple division of labor among specialized
cell types, or
– are very large, dwarfing most eukaryotic cells.
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Prokaryotic Forms
• In many natural environments, prokaryotes attach
to surfaces in a highly organized colony called a
biofilm, which
– may consist of one or several species of
prokaryotes,
– may include protists and fungi,
– can show a division of labor and defense against
invaders, and
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Prokaryotic Forms
– can form on almost any type of surface, including
– rocks,
– metal,
– plastic, and
– organic material including teeth.
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Colorized SEM
Figure 15.10
Prokaryotic Reproduction
• Most prokaryotes can reproduce
– by dividing in half by binary fission and
– at very high rates if conditions are favorable.
• Some prokaryotes form endospores, which are
– thick-coated, protective cells
– produced when the prokaryote is exposed to
unfavorable conditions.
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Figure 15.11
Colorized TEM
Endospore
The Two Main Branches of Prokaryotic Evolution:
Bacteria and Archaea
• By comparing diverse prokaryotes at the
molecular level, biologists have identified two
major branches of prokaryotic evolution:
1. bacteria and
2. archaea (more closely related to eukaryotes).
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The Two Main Branches of Prokaryotic Evolution:
Bacteria and Archaea
• Thus, life is organized into three domains:
1. Bacteria,
2. Archaea, and
3. Eukarya.
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The Two Main Branches of Prokaryotic Evolution:
Bacteria and Archaea
• Some archaea are “extremophiles.”
– Halophiles thrive in salty environments.
– Thermophiles inhabit very hot water.
– Methanogens
– inhabit the bottoms of lakes and swamps and
– aid digestion in cattle and deer.
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Figure 15.13
(a) Salt-loving archaea
(b) Heat-loving archaea
Bacteria and Disease
Bacteria That Cause Disease
• Bacteria and other organisms that cause disease
are called pathogens.
• Most pathogenic bacteria produce poisons.
– Exotoxins are proteins bacterial cells secrete into
their environment.
– Endotoxins are
– not cell secretions but instead
– chemical components of the outer membrane of
certain bacteria.
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Colorized SEM
Figure 15.14
Haemophilus
influenzae
Cells of nasal
lining
Bacteria That Cause Disease
• Lyme disease is
– caused by bacteria carried by ticks and
– treated with antibiotics, if detected early.
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SEM
Figure 15.15
Tick that carries
the Lyme disease
bacterium
“Bull’s-eye” rash
Spirochete that causes
Lyme disease
The Ecological Impact of Prokaryotes
• Pathogenic bacteria are in the minority among
prokaryotes.
• Far more common are species that are essential
to our well-being, either directly or indirectly.
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Prokaryotes and Chemical Recycling
• Prokaryotes play essential roles in
– chemical cycles in the environment and
– the breakdown of organic wastes and dead
organisms.
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Prokaryotes and Bioremediation
• Bioremediation is the use of organisms to
remove pollutants from
– water,
– air, and
– soil.
• A familiar example is the use of prokaryotic
decomposers in sewage treatment.
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Figure 15.17
Rotating arm spraying
liquid wastes
Rock bed coated
with aerobic
prokaryotes and
fungi
Liquid wastes
Outflow
Figure 15.UN01
Bacteria
Prokaryotes
Archaea
Protists
Eukarya
Plants
Fungi
Animals
Figure 15.UN02
Bacteria
Prokaryotes
Archaea
Protists
Eukarya
Plants
Fungi
Animals
Figure 15.UN03
Major episode
Millions of years ago
Plants and fungi colonize land
All major animal phyla established
First multicellular organisms
Oldest eukaryotic fossils
Accumulation of O2 in atmosphere
Oldest prokaryotic fossils
Origin of Earth
500
530
1,200
1,800
2,400
3,500
4,600
Figure 15.UN05
Spherical
Rod-shaped
Spiral