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

Fig. 4-4, p. 68

Nicheseparation

Specialist specieswith a narrow niche

Generalist specieswith a broad niche

Nichebreadth

Region ofniche overlap

Niches of Specialist and Generalist Species

Resource use

Nu

mb

er o

f in

div

idu

als

Specialized Feeding Niches in Birds

Fig. 4-5, p. 68

Louisiana heronwades into waterto seize small fish

Black skimmerseizes small fishat water surface

Ruddy turnstone searches

under shells and pebbles

for small invertebratesAvocet sweeps bill

through mud and surface water in search of small crustaceans, insects, and seeds

Brown pelican dives for fish, which it locates from the air

Dowitcher probesdeeply into mud insearch of snails,marine worms, andsmall crustaceans

Herring gullis a tirelessscavenger

Flamingo feeds onminute organismsin mud

Scaup and other divingducks feed on mollusks,crustaceans, and aquaticvegetation

Piping plover feeds on insects and tiny crustaceans on sandy beachesKnot (sandpiper)

picks up wormsand small crustaceansleft by receding tide

Oystercatcher feeds onclams, mussels, and othershellfish into which itpries its narrow beak

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

Fig. 4-A, p. 69

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

Fig. 4-3, p. 67

Present

65 million years ago

135 million years ago

225 million years ago

Present225 million years ago65 million years ago135 million years ago

Fig. 4-3, p. 67

Stepped Art

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

Fig. 4-4, p. 67

18,000years beforepresent

Modern day(August)

Northern HemisphereIce coverage

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.

Unique Roles for Species

Generalist species

Specialist species

Specialists prone to extinction – giant panda

Panda and its Food

Panda and its Food

Fig. 4-4, p. 68

Nicheseparation

Specialist specieswith a narrow niche

Generalist specieswith a broad niche

Nichebreadth

Region ofniche overlap

Niches of Specialist and Generalist Species

Resource use

Nu

mb

er o

f in

div

idu

als

Specialized Feeding Niches in Birds

Fig. 4-5, p. 68

Louisiana heronwades into waterto seize small fish

Black skimmerseizes small fishat water surface

Ruddy turnstone searches

under shells and pebbles

for small invertebratesAvocet sweeps bill

through mud and surface water in search of small crustaceans, insects, and seeds

Brown pelican dives for fish, which it locates from the air

Dowitcher probesdeeply into mud insearch of snails,marine worms, andsmall crustaceans

Herring gullis a tirelessscavenger

Flamingo feeds onminute organismsin mud

Scaup and other divingducks feed on mollusks,crustaceans, and aquaticvegetation

Piping plover feeds on insects and tiny crustaceans on sandy beachesKnot (sandpiper)

picks up wormsand small crustaceansleft by receding tide

Oystercatcher feeds onclams, mussels, and othershellfish into which itpries its narrow beak

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

Fig. 4-A, p. 69

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

Fig. 4-6, p. 70

Spreads northwardand southwardand separates

Arctic Fox

Gray Fox

Different environmentalconditions lead to differentselective pressures and evolutioninto two different species.

Adapted to coldthrough heavier fur, short ears, short legs, and short nose. White fur matches snow for camouflage.

Adapted to heat through lightweightfur and long ears, legs, and nose, whichgive off more heat.

Northernpopulation

Southernpopulation

Early foxpopulation

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

Fig. 4-8a, p. 72

Phase 1Gene Transfer Preparations

Host cell

Enzymes integrate plasmidinto host cell DNA.

A. tumefaciens(agrobacterium)

Agrobacterium takes up plasmid

Foreign gene integrated intoplasmid DNA, which can beused as a vector

plasmid

Extractplasmid

A. tumefaciens

Plant cell

Foreign geneif interest

Extract DNA

Phase 2Make Transgenic Cell

Fig. 4-8b, p. 72

Phase 3Grow GeneticallyEngineered Plant

Foreign DNAHost DNA

Nucleus Transgenicplant cell

Cell division oftransgenic cells

Cultured cellsdivide and growinto plantlets(otherwiseteleological)

Transgenic plantswith desired trait

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

Video: Ancient Human Skull

PLAYVIDEO

Video: Asteroid Menace

PLAYVIDEO

Video: Bachelor Pad at the Zoo

PLAYVIDEO

Video: Cloned Pooch

PLAYVIDEO

Video: Creation vs. Evolution

PLAYVIDEO

Video: Dinosaur Discovery

PLAYVIDEO

Video: Glow-in-the-Dark Pigs

PLAYVIDEO

Video: Hsing Hsing Dies

PLAYVIDEO

Video: Mule Clones

PLAYVIDEO

Video: New Species Found

PLAYVIDEO

Video: Penguin Rescue

PLAYVIDEO