Transcript Document

Biodiversity and Evolution
Chapter 4
4-1 What Is Biodiversity and Why
Is It Important?
 Concept 4-1 The biodiversity found in genes,
species, ecosystems, and ecosystem processes
is vital to sustaining life on earth.
Natural Capital: Major Components of
the Earth’s Biodiversity
Fig 4.2
Why Should We Care About Biodiversity?
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Aesthetic pleasure
Ecological: (environmental monitor, ecological
balance – keystone species)
Educational
Historical or cultural
Natural Services: (air and water purification, soil
fertility, waste disposal,)
Recreational
Medicine
Agriculture: (biological pest control, food
source, commercial product – wood)
Moral or ethics
4-2 Where Do Species Come From?
 Concept 4-2A The scientific theory of evolution
explains how life on earth changes over time
through changes in the genes of populations.
 Concept 4-2B 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).
ORIGINS OF LIFE
 1 billion years of chemical change to form the
first cells, followed by about 3.7 billion years of
biological change.
Biological
Evolution
 This has led to
the variety of
species we find
on the earth
today.
Figure 4-2
Animation: Evolutionary Tree of Life
PLAY
ANIMATION
Six Major Kingdoms of Species as
a Result of Natural Selection
Fig 4.3
How Do We Know Which Organisms Lived
in the Past?
 Our knowledge about
past life comes from
fossils, chemical
analysis, cores drilled
out of buried ice, and
DNA analysis.
Figure 4-4
The Genetic Makeup of a Population
Can Change
 Populations evolve by becoming genetically
different
 Genetic variations
• First step in biological evolution
• Occurs through mutations in reproductive cells
• Mutations: random changes in the structure or
number of DNA molecules in a cell that can be
inherited by offspring.
Individuals in Populations with Beneficial
Genetic Traits Can Leave More Offspring
 Natural selection: acts on individuals
• Second step in biological evolution
• Adaptation may lead to differential reproduction
• Genetic resistance
 When environmental conditions change,
populations
• Adapt
• Migrate
• Become extinct
Natural Selection and Adaptation: Leaving
More Offspring With Beneficial Traits
 Three conditions are necessary for biological
evolution:
• Genetic variability, traits must be heritable, trait
must lead to differential reproduction.
 An adaptive trait is any heritable trait that
enables an organism to survive through natural
selection and reproduce better under prevailing
environmental conditions.
Evolution by Natural Selection
Fig 4.5
Three Common Myths about Evolution
through Natural Selection
 “Survival of the fittest” is not “survival of the
strongest”
 Organisms do not develop traits out of need or
want
 No grand plan of nature for perfect adaptation
Animation: Disruptive Selection
PLAY
ANIMATION
Animation: Stabilizing Selection
PLAY
ANIMATION
Animation: Evolutionary Tree Diagrams
PLAY
ANIMATION
Coevolution: A Biological Arms Race
 Interacting species can engage in a back and
forth genetic contest in which each gains a
temporary genetic advantage over the other.
• This often happens between predators and prey
species.
4-3 How Do Geological Processes and
Climate Change Affect Evolution?
 Concept 4-3 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.
Movement of the Earth’s Continents
over Millions of Years
Fig 4.6
Changes in Ice Coverage in the Northern
Hemisphere During the last 18,000 Years
Fig 4.7
4-4 How Do Speciation, Extinction, and
Human Activities Affect Biodiversity?
 Concept 4-4A As environmental conditions
change, the balance between formation of new
species and extinction of existing species
determines the earth’s biodiversity.
 Concept 4-4B Human activities can decrease
biodiversity by causing the premature extinction
of species and by destroying or degrading
habitats needed for the development of new
species.
Cenozoic
Era
Period
Millions of
years ago
Quaternary
Today
Tertiary
65
Mesozoic
Cretaceous
Jurassic
180
Triassic
Species and families
experiencing
mass extinction
Extinction Current extinction crisis caused
by human activities. Many species
are expected to become extinct
Extinction within the next 50–100 years.
Cretaceous: up to 80% of ruling
reptiles (dinosaurs); many marine
species including many
foraminiferans and mollusks.
Extinction
Triassic: 35% of animal families,
including many reptiles and marine
mollusks.
Bar width represents relative
number of living species
250
Extinction
345
Extinction
Permian
Paleozoic
Carboniferous
Devonian
Permian: 90% of animal families,
including over 95% of marine
species; many trees, amphibians,
most bryozoans and brachiopods,
all trilobites.
Devonian: 30% of animal
families, including agnathan and
placoderm fishes and many
trilobites.
Silurian
Ordovician
Cambrian
500
Extinction
Ordovician: 50% of animal
families, including many
trilobites.
Geographic Isolation Can Lead to
Reproductive Isolation
Fig 4.8
GENETIC ENGINEERING AND THE FUTURE
OF EVOLUTION
 We have used artificial selection to change the
genetic characteristics of populations with similar
genes through selective breeding.
 We have used genetic
engineering to transfer
genes from one species
to another.
Figure 4-A
Genetic Engineering:
Genetically Modified Organisms (GMO)
 GMOs use
recombinant DNA
• genes or portions
of genes from
different
organisms.
4-5 What Is Species Diversity and Why
Is It Important?
 Concept 4-5 Species diversity is a major
component of biodiversity and tends to increase
the sustainability of ecosystems.
Why Should We Care About Biodiversity?
•
•
•
•
•
•
•
•
•
Aesthetic pleasure
Ecological: (environmental monitor, ecological
balance – keystone species)
Educational
Historical or cultural
Natural Services: (air and water purification, soil
fertility, waste disposal,)
Recreational
Medicine
Agriculture: (biological pest control, food
source, commercial product – wood)
Moral or ethics
Variations in Species Richness and
Species Evenness
Species-Rich Ecosystems Tend to Be
Productive and Sustainable
 Species richness seems to increase productivity
and stability or sustainability
 How much species richness is needed is
debatable
Animation: Speciation on an Archipelago
PLAY
ANIMATION
Evolutionary Divergence
 Each species has a
beak specialized to
take advantage of
certain types of food
resource.
4-6 What Roles Do Species Play in
Ecosystems?
 Concept 4-6A Each species plays a specific
ecological role called its niche.
 Concept 4-6B Any given species may play one
or more of five important roles—native,
nonnative, indicator, keystone, or foundation
roles—in a particular ecosystem.
Each Species Plays a Unique Role
in Its Ecosystem
 Ecological niche, niche
• Pattern of living
 Generalist species
• Broad niche
 Specialist species
• Narrow niche
ECOLOGICAL NICHES AND ADAPTATION
 Each species in an ecosystem has a specific
role or way of life.
• Fundamental niche: the full potential range of
physical, chemical, and biological conditions and
resources a species could theoretically use.
• Realized niche: to survive and avoid competition,
a species usually occupies only part of its
fundamental niche.
Specialist Species and Generalist
Species Niches
Fig 4.11
Specialized Feeding Niches
 Resource partitioning reduces competition
and allows sharing of limited resources.
Figure 4-13
Niches Can Be Occupied by Native and
Nonnative Species
 Native species
 Nonnative species; invasive, alien, or exotic
species
• May spread rapidly
• Not all are villains
Indicator Species Serve as Biological
Smoke Alarms
 Indicator species
• Can monitor environmental quality
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Trout
Birds
Butterflies
Frogs
Case Study: Why Are Amphibians
Vanishing? (1)
 Habitat loss and fragmentation
 Prolonged drought
 Pollution
 Increase in UV radiation
 Parasites
 Viral and fungal diseases
 Climate change
 Overhunting
 Nonnative predators and competitors
Case Study: Why Are Amphibians
Vanishing? (2)
 Importance of amphibians
• Sensitive biological indicators of environmental
changes
• Adult amphibians
• Important ecological roles in biological
communities
• Genetic storehouse of pharmaceutical products
waiting to be discovered
Life Cycle of a Frog
Fig 4.14
Keystone, Foundation Species Determine
Structure, Function of Their Ecosystems
 Keystone species
• Pollinators
• Top predator
 Foundation species
• Create or enhance their habitats, which benefit
others
• Elephants
• Beavers
Why Should We Care About Biodiversity?
•
•
•
•
•
•
•
•
•
Aesthetic pleasure
Ecological: (environmental monitor, ecological
balance – keystone species)
Educational
Historical or cultural
Natural Services: (air and water purification, soil
fertility, waste disposal,)
Recreational
Medicine
Agriculture: (biological pest control, food
source, commercial product – wood)
Moral or ethics