Evolution and Biodiversity
Chapter 4
Concept 4-3 As a result of biological evolution, each
species plays a specific ecological role called its niche.
Niche – sometimes thought of as the job or
vocation of a species; involves all of its
environment
Habitat – the place where an organism lives;
where you would go to find this organism
Unique Roles for Species
• Generalist species
• Specialist species
• Specialists prone to extinction – giant
panda
Core Case Study: Life on Earth
 Uniquely suited for life
•
•
•
•
Temperature range
Liquid water
Gravitational mass
Oxygen
 Organisms contribute to relatively consistent
planetary conditions – resilient and adaptive
 Biodiversity and sustainability
Panda and its Food
Number of individuals
Niches of Specialist and Generalist
Species
Specialist species
with a narrow niche
Niche
separation
Generalist species
with a broad niche
Niche
breadth
Region of
niche overlap
Resource use
Specialized Feeding Niches in
Birds
Herring gull
is a tireless
scavenger
Black skimmer
seizes small fish
at water surface
Flamingo feeds on
minute organisms
in mud
Brown pelican
dives for fish,
which it locates
from the air
Avocet sweeps bill
through mud and
surface water in
search of small
crustaceans, insects,
and seeds
Louisiana heron
wades into water
to seize small fish
Scaup and other diving
ducks feed on mollusks,
crustaceans, and aquatic
vegetation
Ruddy
turnstone
searches
under shells
and pebbles
for small
invertebrates
Dowitcher probes
deeply into mud in
search of snails,
marine worms, and
small crustaceans
Oystercatcher feeds on
clams, mussels, and other
shellfish into which it
pries its narrow beak
Piping plover
feeds on insects
and tiny
crustaceans on
sandy beaches
Knot (sandpiper)
picks up worms
and small crustaceans
left by receding tide
Fig. 4-5, p. 68
Science Focus: Cockroaches
• Existed for 350 million years – 3,500
known species
• Highly adapted, rapidly producing
generalists
– Consume almost anything
– Endure food shortage
– Survive everywhere except polar regions
– Avoid predation
Cockroaches: Nature’s Ultimate
Survivors
The Right Mix of Conditions
Fig. 4-1, p. 63
4-1 What Is Biological Evolution and How
Does It Occur?
 Concept 4-1A The scientific theory of evolution
explains how life on earth changes over time
through changes in the genes of populations.
 Concept 4-1B Populations evolve when genes
mutate and give some individuals genetic traits
that enhance their abilities to survive and to
produce offspring with these traits (natural
selection).
Theory of Evolution
 4.7 billion years
 Explains why life so diverse
 Supported by fossils, chemical analysis of
primitive rock, DNA, and ice cores
Fossilized Skeleton of a Cenozoic
Herbivore
Fig. 4-2, p. 65
Population Changes over Time
 Populations evolve by becoming genetically
different
 Genetic variability – mutation
Natural Selection
 Genetically favorable traits to survive and
reproduce
 Trait – heritable and lead to differential
reproduction
 Faced with environmental change
• Adapt
• Migrate
• Become extinct
Coevolution
 Changes in gene pool of one species lead to
changes in gene pool of the other
 Bats and moths
Science Focus: How Did We Become
Such a Powerful Species?
 Key adaptations – also enabled us to modify
environment
 Evolved very recently
 Technology dominates earth’s life support
systems and NPP
4-2 How Do Geological and Climate
Changes Affect Evolution?
 Concept 4-2 Tectonic plate movements,
volcanic eruptions, earthquakes, and climate
change have shifted wildlife habitats, wiped out
large numbers of species, and created
opportunities for the evolution of new species.
Plate Tectonics
 Locations of continents and oceans determine
earth’s climate
 Movement of continents allow species to move
and adapt
 Earthquakes and volcanoes affect biological
evolution
Movement of Continents
225 million years ago
135 million years ago
65 million years ago
Present
Fig. 4-3, p. 67
225
million
years
ago
65
135
million
years
ago
Present
Stepped Art
Fig. 4-3, p. 67
Earth’s Long-term Climate Changes
 Cooling and warming periods – affect evolution
and extinction of species
 Five mass extinctions
• Eliminated half of the earth’s species
• Many theories why this occurred
 Opportunities for the evolution of new species
Northern Hemisphere over 18,000 Years
18,000
years before
present
Northern Hemisphere
Ice coverage
Modern day
(August)
Fig. 4-4, p. 67
4-3 What Is an Ecological Niche?
 Concept 4-3 As a result of biological evolution,
each species plays a specific ecological role
called its niche.
 Generalist species
 Specialist species
Unique
Specialists
prone
extinction – giant panda
Roles
fortoSpecies
Panda and its Food
Panda and its Food
Number of individuals
Niches of Specialist and Generalist
Species
Specialist species
with a narrow niche
Niche
separation
Generalist species
with a broad niche
Niche
breadth
Region of
niche overlap
Resource use
Specialized Feeding Niches in Birds
Herring gull
is a tireless
scavenger
Black skimmer
seizes small fish
at water surface
Flamingo feeds on
minute organisms
in mud
Brown pelican
dives for fish,
which it locates
from the air
Avocet sweeps bill
through mud and
surface water in
search of small
crustaceans, insects,
and seeds
Louisiana heron
wades into water
to seize small fish
Scaup and other diving
ducks feed on mollusks,
crustaceans, and aquatic
vegetation
Ruddy
turnstone
searches
under shells
and pebbles
for small
invertebrates
Dowitcher probes
deeply into mud in
search of snails,
marine worms, and
small crustaceans
Oystercatcher feeds on
clams, mussels, and other
shellfish into which it
pries its narrow beak
Piping plover
feeds on insects
and tiny
crustaceans on
sandy beaches
Knot (sandpiper)
picks up worms
and small crustaceans
left by receding tide
Fig. 4-5, p. 68
Science Focus: Cockroaches
 Existed for 350 million years – 3,500 known
species
 Highly adapted, rapidly producing generalists
•
•
•
•
Consume almost anything
Endure food shortage
Survive everywhere except polar regions
Avoid predation
 Carry human diseases
Cockroaches: Nature’s Ultimate
Survivors
4-4 How Do Extinction, Speciation, and
Human Activities Affect Biodiversity?
 Concept 4-4A As environmental conditions
change, the balance between formation of new
species and extinction of existing ones
determines the earth’s biodiversity.
 Concept 4-4B Human activities decrease the
earth’s biodiversity by causing the premature
extinction of species and by destroying or
degrading habitats needed for the development
of new species.
Speciation
 Geographic isolation
 Reproductive isolation
 Millions of years in slow-producing species
 Hundreds of years in rapidly reproducing
species
Geographic Isolation
Arctic Fox
Northern
population
Early fox
population
Spreads
northward
and southward
and separates
Adapted to cold
through heavier
fur, short ears,
short legs, and
short nose.
White fur
matches snow
for camouflage.
Different environmental
conditions lead to different
selective pressures and evolution
into two different species.
Gray Fox
Southern
population
Adapted to
heat through
lightweight
fur and long
ears, legs, and
nose, which
give off more
heat.
Fig. 4-6, p. 70
Extinction
 Endemic species vulnerable to extinction
 Background extinction
 Mass extinction
 Balance between speciation and extinction
determines biodiversity of earth
 Speciation generally more rapid than extinction
Extinction through Habitat Loss
Fig. 4-7, p. 70
Human Activities and Extinction
 Cause premature extinction of species
 Earth took millions of years to recover from
previous mass extinctions
4-5 How Might Genetic Engineering
Affect the Earth’s Life?
 Concept 4-5 Genetic engineering enables
scientists to transfer genetic traits between
different species – a process that holds great
promise and raises difficult issues.
Humans Change Population Genetics
 Artificial selection – slow process
 Selective breeding
 Crossbreeding – not a form of speciation
 Genetic engineering
Results of Genetic Engineering
 Genetically modified organisms (GMOs)
 Gene splitting rapid vs. artificial selection
 Modified crops, new drugs, fast-growing animals
Steps in Genetic Engineering (1)
Steps in Genetic Engineering (2)
Fig. 4-8, p. 72
Phase 1
Gene Transfer Preparations
A. tumefaciens
Plant cell
Extract DNA
Extract
plasmid
plasmid
Foreign gene
if interest
Foreign gene integrated into
plasmid DNA, which can be
used as a vector
Agrobacterium takes up plasmid
Phase 2
Make Transgenic Cell
A. tumefaciens
(agrobacterium)
Enzymes integrate plasmid
into host cell DNA.
Host cell
Fig. 4-8a, p. 72
Foreign DNA
Host DNA
Nucleus
Transgenic
plant cell
Phase 3
Grow Genetically
Engineered Plant
Cell division of
transgenic cells
Cultured cells
divide and grow
into plantlets
(otherwise
teleological)
Transgenic plants
with desired trait
Fig. 4-8b, p. 72
Pros and Cons of Genetic Engineering
 Pros
• May help cure genetic defects
• May improve organisms
• May lead to development of secondary evolution
 Cons
•
•
•
•
Ethical issues
Privacy issues
Designer babies
GMO crossbreeding with original organisms
Genetically Engineered Mice
Fig. 4-9, p. 73
Animation: Carbon Bonds
Animation: Stanley Miller’s Experiment
Animation: Evolutionary Tree of Life
Animation: Stabilizing Selection
Animation: Disruptive Selection
Animation: Moth Populations
Animation: Adaptive Trait
Animation: Speciation on an Archipelago
Animation: Evolutionary Tree Diagrams
Animation: Gause’s Competition Experiment
Animation: Species Diversity By Latitude
Animation: Humans Affect Biodiversity
Animation: Habitat Loss and Fragmentation
Animation: Transferring Genes into Plants
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