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SUSTAINING THE
MILLER/SPOOLMAN
EARTH | G. TYLER MILLER | SCOTT E. SPOOLMAN
11e
3
Biodiversity and
Evolution
© Cengage Learning 2015
3-1 What Is Biodiversity and Why
Is It Important?
• Crucial part of the earth’s natural capital
– Genetic diversity
– Species diversity
– Ecological diversity
– Functional diversity
• The earth’s biodiversity
– Helps keep us alive and supports our
economies
© Cengage Learning 2015
Functional Diversity The biological and chemical
processes such as energy flow and matter recycling
needed for the survival of species, communities,
and ecosystems.
Genetic Diversity The variety
of genetic material within a
species or a population.
Fig. 3-1
Ecological Diversity The variety of
terrestrial and aquatic ecosystems found
in an area or on the earth.
Species Diversity The number and
abundance of species present in
different communities.
3-2 Where Do Species Come From?
• Biological evolution by natural selection
explains how life changes over time
– Survival traits become more evident through
the process of natural selection
– Fossils provide physical evidence
– Details of evolution
• Still many unanswered questions
© Cengage Learning 2015
Evolution by Natural Selection Works
through Mutations and Adaptation
• Populations evolve by becoming
genetically different
• Steps in biological evolution
– Genes mutate
– Individuals are selected
– Populations evolve
• Better adapted to survive and reproduce under
existing environmental conditions
© Cengage Learning 2015
(a)
(b)
Normal bacterium Resistant bacterium
Stepped Art
Fig. 3-2
(c)
(d)
Charles Darwin (1809-1882)
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Adaptation through Natural Selection Has
Limits
• Adaptive genetic traits must precede
change in the environmental conditions
• Reproductive capacity
– Species that reproduce rapidly and in large
numbers are better able to adapt
© Cengage Learning 2015
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
© Cengage Learning 2015
Geological Processes, Catastrophes, and
Climate Change Affect Natural Selection
• Drift of tectonic plates
– Continents’ and oceans’ locations shifted
– Species migrated, adapted to new
environments, and formed new species
through natural selection
• Tectonic plates’ quick shift → earthquakes
• Volcanic eruptions
– Along tectonic plates’ boundaries
© Cengage Learning 2015
Geological Processes, Catastrophes, and
Climate Change
• Long-term climate changes
– Ice ages followed by warming periods
• Collisions between the earth and large
asteroids
– Extinctions
– New species
© Cengage Learning 2015
3-3 How Do Speciation, Extinction, and
Human Activities Affect Biodiversity?
• How do species evolve?
– Speciation: one species splits into two or
more species
– How speciation occurs
• Geographical isolation first and then reproductive
isolation
• Genetic engineering
© Cengage Learning 2015
Adapted to cold through
heavier fur, short ears,
short legs, and short
nose. White fur matches
snow for camouflage.
Arctic Fox
Northern
population
Early fox
population
Different environmental
conditions lead to different
selective pressures and
evolution into two different
species.
Spreads
northward and
southward and
separates
Gray Fox
Southern
population
Adapted to heat through
lightweight fur and long
ears, legs, and nose,
which give off more heat.
Fig. 3-3
Extinction is Forever
• Endemic species: found only in one area
– Particularly vulnerable
• Background extinction rate
• Mass extinction: 3-5 over 500 million years
• Much biodiversity loss
– Due to human activities
© Cengage Learning 2015
© Cengage Learning 2015
3-4 What Are Biomes and How Have
Human Activities Affected Them?
• Climate helps to determine the nature of
biomes
– Biomes: characterized by climate and
dominant vegetation
– Climate differences due to:
• Average annual precipitation
• Average temperature
© Cengage Learning 2015
Fig. 3-4
Biomes Are Grouped According to Their
Characteristics
• Divided into subgroups based on
– Average precipitation and temperature,
latitude, altitude, and locations and sizes of
the nearest bodies of water
• Major types
– Deserts
– Grasslands
– Forests
– Mountains
© Cengage Learning 2015
Cold
Arctic tundra
Evergreen coniferous forest
Temperate
desert
Temperate deciduous forest
Chaparral
Hot
Wet
Cold desert
Temperate
grassland
Tropical desert
Tropical rain forest
Dry
Tropical grassland (savanna)
Fig. 3-5
Humans Have Disturbed Most of
the Earth’s Lands
• Environmental destruction and
degradation is increasing in many parts of
the world
– Preserving natural capital will require
• Protecting remaining wild areas from development
• Restoring many of the land areas that have been
degraded
© Cengage Learning 2015
Natural Capital Degradation
Major Human Impacts on Terrestrial Ecosystems
Deserts
Large desert cities
Destruction of soil and
underground habitat
by off-road vehicles
Grasslands
Conversion to
cropland
Release of CO2 to
atmosphere from
burning grassland
Forests
Clearing for
agriculture, livestock
grazing, timber, and
urban development
Conversion of
diverse forests to
tree plantations
Agriculture
Damage from offroad vehicles
Air pollution blowing in from
urban areas and power plants
Depletion of
groundwater
Overgrazing by
livestock
Land disturbance and
pollution from mineral
extraction
Oil production and
off-road vehicles in Pollution of forest
arctic tundra
streams
Fig. 3-6
Mountains
Timber and
mineral extraction
Hydroelectric dams
and reservoirs
Soil damage from off-road
vehicles
3-5 What Are Aquatic Life Zones and How
Have Human Activities Affected Them?
• Water covers most of the earth and
sustains biodiversity
– Saltwater covers 71 percent of the planet
– Freshwater covers less than 2.2 percent of
earth’s surface
• Aquatic life zones
– Saltwater
– Freshwater
© Cengage Learning 2015
Ocean hemisphere
Fig. 3-7
Land–ocean hemisphere
Water Covers Most of the Earth and
Sustains Biodiversity
• Aquatic life zones
– Key factors determining types and numbers of
organisms in different layers
• Water temperature
• Dissolved oxygen content
• Food availability
• Availability of light and nutrients for
photosynthesis
© Cengage Learning 2015
Oceans Provide Important Ecosystem
and Economic Resources
• Reservoirs of diversity in three major life
zones
– Coastal zone
• Less than 10 percent of world’s ocean
• Ninety percent of all marine species
• High NPP per unit of area
– Open sea
• Vertical zones: euphotic, bathyal, and abyssal
© Cengage Learning 2015
© Cengage Learning 2015
Natural Capital
Marine Ecosystems
Ecological
Services
Oxygen
supplied through
photosynthesis
Water purification
Food
Energy from
waves and tides
Climate
moderation
Pharmaceuticals
CO2 absorption
Harbors and
transportation
routes
Nutrient cycling
Reduced storm
impact (mangroves,
barrier islands,
coastal wetlands)
Biodiversity:
species and habitats
Fig. 3-8
Economic
Services
Recreation and
tourism
Employment
Minerals
Open
Sea
Sea level
Euphotic
Zone
Estuarine
Zone
Twilight
Continental
shelf
Bathyal Zone
Water temperature
drops rapidly between
the euphotic zone and
the abyssal zone in an
area called the
thermocline.
Fig. 3-9
Water temperature (°C)
Photosynthesis
Depth in
meters
Abyssal
Zone
Darkness
High tide
Coastal
Low tide
Zone
Human Activities Are Disrupting and
Degrading Marine Systems
• Major threats to marine systems
– Coastal development
– Overfishing
– Runoff of nonpoint source pollution
– Point source pollution
– Habitat destruction
© Cengage Learning 2015
Natural Capital Degradation
Major Human Impacts on Marine Ecosystems and Coral
Reefs
Marine Ecosystems
Half of coastal wetlands lost to
agriculture and urban development
Over one-fifth of mangrove forests
lost to agriculture, aquaculture,
and development
Beaches eroding due to
development and rising sea levels
Fig. 3-10
Coral Reefs
Ocean bottom habitats degraded
by dredging and trawler fishing
Ocean warming
Rising ocean acidity
Soil erosion
Algae growth from
fertilizer runoff
Bleaching
Rising sea levels
Increased UV exposure
At least 20% of coral reefs
severely damaged and 25–33%
more threatened
Damage from anchors
and from fishing and
diving
Why Are Freshwater Ecosystems
Important?
• Standing (lentic) freshwater bodies
– Lakes
– Ponds
– Inland wetlands
• Flowing (lotic) freshwater systems
– Streams
– Rivers
© Cengage Learning 2015
Natural Capital
Freshwater Systems
Ecological
Services
Economic
Services
Climate
moderation
Food
Nutrient cycling
Drinking water
Waste treatment
Irrigation water
Flood control
Groundwater
recharge
Habitats for many
species
Genetic resources
and biodiversity
Scientific
information
Fig. 3-11
Hydroelectricity
Transportation
corridors
Recreation
Employment
Painted
turtle
Blue-winged
teal
Green
frog
Muskrat
Pond
snail
Littoral zone
Plankton
Diving
beetle
Northern
pike
Yellow
perch
Bloodworms
Why Are Freshwater Ecosystems
Important?
• Lake classification by nutrient content and
primary productivity
– Oligotrophic lakes
• Low levels of nutrients and low NPP
– Eutrophic lakes
• High levels of nutrients and high NPP
– Hypereutrophic lakes
– Mesotrophic lakes
© Cengage Learning 2015
Why Are Freshwater Ecosystems
Important?
•
•
•
•
Surface water
Runoff
Watershed (drainage basin)
Aquatic life zones
– Source zone
– Transition zone
– Floodplain zone
© Cengage Learning 2015
Rain and
snow
Lake
Glacier
Rapids
Waterfall
Tributary
Flood plain
Oxbow lake
Salt marsh
Delta Deposited
sediment
Ocean
Source Zone
Transition Zone
Floodplain Zone
Stepped Art
Fig. 3-13
Water
Sediment
Human Activities Are Disrupting and
Degrading Freshwater Systems
• Dams and canals
– Fragment the world’s largest rivers
• Flood control levees and dikes
– Disconnect rivers from their floodplains and
destroy aquatic habitat
• Pollutants from cities and farms
– Impact water quality
• Drained wetlands
© Cengage Learning 2015