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13e. ENVIRONMENTAL SCIENCE. CHAPTER 4: Biodiversity and Evolution. Core Case Study: Why Are Amphibians Vanishing? (1). Habitat loss and fragmentation Prolonged drought Increased ultraviolet radiation Parasites Viral and fungal diseases. Core Case Study: Why Are Amphibians Vanishing? (2).

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environmental science
13e

ENVIRONMENTALSCIENCE

CHAPTER 4:Biodiversity and Evolution

core case study why are amphibians vanishing 1
Core Case Study: Why Are Amphibians Vanishing? (1)
  • Habitat loss and fragmentation
  • Prolonged drought
  • Increased ultraviolet radiation
  • Parasites
  • Viral and fungal diseases
core case study why are amphibians vanishing 2
Core Case Study: Why Are Amphibians Vanishing? (2)
  • Pollution
  • Climate change
  • Overhunting
  • Nonnative predators and competitors
  • 33% of all amphibian species face extinction
4 1 what is biodiversity and why is it important
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.
biodiversity 1
Biodiversity (1)
  • Species diversity
  • A set of individuals that can mate and produce fertile offspring
  • 8-100 million species total; likely 10-14 million
  • 2 million species identified
  • ~50% in endangered tropical rainforests
biodiversity 2
Biodiversity (2)
  • Genetic diversity
  • Ecosystem diversity
    • Biomes
      • Distinct climate
      • Certain species, especially vegetation
  • Functional diversity
slide9
Functional Diversity

The biological and chemical processes such as energy

flow and matter recycling needed for the survival of species,

communities, and ecosystems.

Ecological Diversity

The variety of terrestrial and

aquatic ecosystems found in

an area or on the earth.

Genetic Diversity

The variety of genetic material

within a species or a population.

Species Diversity

The number and abundance of species

present in different communities

Fig. 4-2, p. 61

slide12
Average annual precipitation

100-125 cm (40-50 in.)

75-100 cm (30-40 in.)

50-75 cm (20-30 in.)

25-50 cm (10-20 in.)

below-25 cm (0-10 in.)

Denver

Baltimore

San Francisco

St. Louis

Las Vegas

Coastal mountain

ranges

Sierra Nevada

Rocky

Mountains

Great American

Desert

Mississippi

River Valley

Great

Plains

Appalachian

Mountains

Coastal chaparral

and scrub

Coniferous forest

Desert

Coniferous forest

Prairie grassland

Deciduous forest

Fig. 4-4, p. 63

science focus insects
Science Focus: Insects
  • Around for ~400 million years
  • Bad reputation
  • Useful to humans and ecosystems
  • Vital roles in sustaining life
    • Pollinators
    • Natural pest control
    • Renewing soils
4 2 how does the earth s life change over time
4-2 How Does the Earth’s Life Change over Time?
  • 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).
theory of evolution
Theory of Evolution
  • Fossils
    • Mineralized and petrified remains
    • Skeletons, bones, and shells
    • Leaves and seeds
    • Impressions in rocks
    • Fossil record incomplete: ~1% of all species
  • Charles Darwin, On the Origin of Species, 1859
population changes over time
Population Changes over Time
  • Populations evolve by becoming genetically different over time
  • Genetic variability – mutations
    • Random changes in DNA molecules in genes
    • Can occur spontaneously
    • External agents: radiation
    • Can create a heritable trait
natural selection
Natural Selection
  • Adaptive traits - genetically favorable traits that increase the probability to survive and reproduce
  • Trait – heritable and lead to differential reproduction
  • Faced with environmental change
    • Adapt through evolution
    • Migrate
    • Become extinct
evolution through natural selection summarized
Evolution through Natural Selection Summarized
  • Genes mutate, individuals are selected, and populations evolve such that they are better adapted to survive and reproduce under existing environmental conditions.
slide22
(a)

(b)

(c)

(d)

A group of bacteria, including genetically resistant ones, are exposed to an antibiotic

Most of the normal bacteria die

The genetically resistant bacteria start multiplying

Eventually the resistant strain

replaces all or most of the strain affected by the antibiotic

Normal bacterium

Resistant bacterium

Fig. 4-5, p. 65

slide23
A group of bacteria, including genetically resistant ones, are

exposed to an antibiotic

Eventually the resistant strain

replaces the strain affected by

the antibiotic

The genetically resistant bacteria

start multiplying

Most of the normal bacteria die

Normal bacterium

Resistant bacterium

Stepped Art

Fig. 4-5, p. 83

adaptation through natural selection has limits
Adaptation through Natural Selection Has Limits
  • Humans unlikely to evolve and have skin that’s not harmed by UV radiation
  • Desired trait must already be in the gene pool.
  • Must have high reproductive capacity so adaptive traits can be spread rapidly
three myths about evolution through natural selection refuted
Three Myths about Evolution through Natural Selection Refuted
  • “Survival of the fittest” does not mean “survival of the strongest”
  • Organisms don’t develop traits just because they would be useful: giraffes and long necks
  • There is no grand plan of nature to create more perfectly adapted species – no trend toward genetic perfection
science focus how did we become such a powerful species
Science Focus: How Did We Become Such a Powerful Species?
  • Key adaptations – also enabled us to modify environment
    • Opposable thumbs
    • Walk upright
    • Complex brains
      • Transmit ideas to others
      • Develop technologies to alter environment

Technology dominates earth’s life support systems and NPP

4 3 how do geological processes and climate changes affect evolution
4-3 How Do Geological Processes and Climate Changes 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.
plate tectonics
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 by separating populations of a species and allowing new species to develop
slide30
225 million years ago

135 million years ago

65 million years ago

Present

Fig. 4-6, p. 66

slide31
225 million years ago

65 million years ago

135 million years ago

Present

Stepped Art

Fig. 4-6, p. 66

earth s long term climate changes
Earth’s Long-Term Climate Changes
  • Cooling and warming periods – affect evolution and extinction of species
    • Change ocean levels and area
    • Glaciers expanding and contracting
    • Climate changes
  • Opportunities for the evolution of new species
  • Many species go extinct
slide34
18,000

years before

present

Northern Hemisphere

Ice coverage

Modern day

(August)

Legend

Continental ice

Sea ice

Land above sea level

Fig. 4-7, p. 67

science focus earth is just right for life to thrive
Science Focus: Earth is Just Right for Life to Thrive
  • Life needs a temperature range that results in liquid water
  • Earth’s orbit: right distance from sun
  • Earth’s optimal gravity: keeps atmosphere
  • Favorable temperature range over earth history has promoted evolution and biodiversity
  • Favorable oxygen level in atmosphere
4 4 how do speciation extinction and human activities affect biodiversity
4-4 How Do Speciation, Extinction, and Human Activities Affect Biodiversity?
  • Concept 4-4 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
Speciation
  • Speciation
    • One species splits into two or more species that can no longer breed and produce fertile offspring
  • Geographic isolation
  • Reproductive isolation
slide39
Adapted to cold

through heavier fur, short ears, short legs, and short nose. White fur matches snow for camouflage.

Arctic Fox

Northern

population

Spreads northward

and southward

and separates

Different environmental

conditions lead to different

selective pressures and evolution

into two different species.

Early fox

population

Gray Fox

Adapted to heat through lightweight

fur and long ears, legs, and nose, which

give off more heat.

Southern

population

Fig. 4-8, p. 68

science focus changing genetic traits
Science Focus: Changing Genetic Traits
  • Artificial selection
    • Selective breeding: crossbreeding varieties within same species to enhance desired traits
    • Grains, fruits, vegetables, dogs, other animals
  • Genetic engineering
    • Add, delete, or alter DNA segments
    • Add desirable genes from other species
    • New drugs, pest-resistant plants
    • Controversial
extinction 1
Extinction (1)
  • Biological extinction
    • Entire species gone
  • Local extinction
    • All members of a species in a specific area gone
  • Endemic species vulnerable to extinction
  • Background extinction
  • Speciation generally more rapid than extinction
extinction 2
Extinction (2)
  • Mass extinction
    • Earth took millions of years to recover from previous mass extinctions
  • Balance between speciation and extinction determines biodiversity of earth
  • Humans cause premature extinction of species
human activities and extinction
Human Activities and Extinction
  • Cause premature extinction of species
4 5 what is species diversity and why is it important
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 some ecosystems.
species diversity
Species Diversity
  • Species richness
  • Species evenness
  • Varies with geographic location
  • Species richness declines towards poles
richness and sustainability
Richness and Sustainability
  • Hypothesis
    • Does a community with high species richness have greater sustainability and productivity?
  • Research suggests “yes”
4 6 what roles do species play in an ecosystem
4-6 What Roles Do Species Play in an Ecosystem?
  • Concept 4-6 Each species plays a specific ecological role called its niche.
ecological niche 1
Ecological Niche (1)
  • Species occupy unique niches and play specific roles in an ecosystem
  • Includes everything required for survival and reproduction
    • Water
    • Sunlight
    • Space
    • Temperatures
    • Food requirements
ecological niche 2
Ecological Niche (2)
  • Generalist species
  • Specialist species
  • Native species
  • Nonnative species
    • Spread in new, suitable niches
slide51
Ruddy turnstone searches under shells and pebbles

for small invertebrates

Herring gull

is a tireless

scavenger

Avocet 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 probes

deeply into mud in

search of snails,

marine worms, and

small crustaceans

Black skimmer

seizes small fish

at water surface

Flamingo feeds on

minute organisms

in mud

Louisiana heron

wades into water

to seize small fish

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

Scaup and other diving

ducks feed on mollusks,

crustaceans, and aquatic

vegetation

Knot (sandpiper)

picks up worms

and small crustaceans

left by receding tide

Fig. 4-10, p. 72

science focus cockroaches
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
indicator species
Indicator Species
  • Early warning system
  • Fish
  • Birds
  • Butterflies
  • Amphibians
slide56
Adult frog

(3 years)

Young frog

Tadpole

develops

into frog

Sperm

Sexual

reproduction

Tadpole

Eggs

Fertilized egg

development

Egg hatches

Organ formation

Fig. 4-12, p. 74

keystone species
Keystone Species
  • Significant role in their food web: large affect on types and abundances of other species in an ecosystem
  • Elimination may alter structure and/or function of ecosystem
  • Pollinators
  • Top predators
foundation species
Foundation Species
  • Create habitats and ecosystems
  • Beavers
  • Elephants
  • Seed dispersers
science focus american alligator
Science Focus: American Alligator
  • Highly adaptable
  • Only natural predator is humans
  • 1967 – endangered species list
  • Successful environmental comeback
  • Keystone species
case study why should we protect sharks
Case Study: Why Should WeProtect Sharks?
  • Remove injured, sick animals
  • Many are gentle giants
  • Provide potential insight into cures for human diseases such as cancer
  • Keystone species
  • Hunted and killed by humans
three big ideas from this chapter 1
Three Big Ideas from This Chapter - #1
  • 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).
three big ideas from this chapter 2
Three Big Ideas from This Chapter - #2
  • Human activities are decreasing the earth’s vital biodiversity by causing the premature extinction of species and by disrupting habitats needed for the development of new species.
three big ideas from this chapter 3
Three Big Ideas from This Chapter - #3
  • Each species plays a specific ecological role in the ecosystem where it is found (ecological niche).
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