Unit 9: Ecology

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Unit 9 Ecology

• Chapters 50 55

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Chapter 50

• Introduction to Ecology and the Biosphere

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Ecology is the study of

• distribution and abundance of organisms
• their interactions with other organisms
• their interactions with their physical
  environment
• Think about your favorite spot in nature, and
  write a summary of what that place is like
  utilizing all of your senses

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Key TermsDiscuss the meaning of the following
terms within your group

1. Population
2. Community
3. Ecosystem
4. Biosphere
5. Habitat
6. Niche
7. Abiotic
8. Biotic

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1. Population Group of same species living in the
   same area
2. Community Group of populations living in the
   same area
3. Ecosystem Interrelationships between the
   organisms in a community and their physical
   environment
4. Biosphere All the regions of Earth that contain
   living things
5. Habitat Type of place where an organisms lives
6. Niche Describes all of the biotic and abiotic
   resources in the environment used by an organism
7. Abiotic Non living chemical and physical
   factors
8. Biotic Living organisms in an environment

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Describe how the following terms relate to that
favorite spot

1. Population
2. Community
3. Ecosystem
4. Biosphere
5. Habitat
6. Niche
7. Abiotic
8. Biotic

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Major Abiotic Factors

• Temperature
• Water
• Sunlight
• Wind
• Rocks and Soil
• Periodic Disturbances
• These factors play an important role in the
  climate and distribution of organisms around Earth

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Global Climate Patterns

1. The cause of the seasons
2. Global Air Circulation, precipitation, and winds
3. Rain Shadows

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The Cause of Seasons
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Air Circulation and Precipitation
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Rain Shadow Effect
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Biomes

• Biosphere divided into regions (Biomes) that
  exhibit common environmental characteristics.
• Major Biomes
• Tropical Rain Forests
• Savannahs
• Temperate Grasslands
• Temperate Deciduous Forests
• Deserts
• Taigas
• Tundras
• Fresh Water Biomes
• Marine Biomes

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Tropical Rain Forest

• High Temperature
• Heavy Rainfall
• Epiphytes commensalistic plants that live on
  other plants

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Savannahs

• Grasslands with scattered trees
• High Temperatures
• Little Water

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Temperate Deciduous Forests

• Warm summers and cold winters
• Moderate Precipitation
• Tress shed leaves during winter (adapting for
  short days and cold temperatures)

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Deserts

• Hot and Dry
• Plant growth limited to short periods following
  rains

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Taiga

• Coniferous forests (Pines, firs, and other
  needles leaf trees)
• Cold winters
• Precipitation is in the form of snow

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Tundra

• Winters so cold that ground freezes
• In summer, topsoil thaws, but permafrost remains
  frozen
• Grassland type of community supported in summer

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Fresh Water

• Ponds
• Lakes
• Streams
• Rivers

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Marine

• Estuaries (Oceans meet rivers)
• Intertidal Zones (oceans meet land)
• Continental shelves (shallow oceans bordering
  continents)
• Coral Reefs
• Pelagic Ocean (deep ocean)

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Behavioral Biology

• Chapter 51

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Key Topics

• Introduction to Behavior and Behavioral Ecology
• Learning
• Animal Cognition
• Social Behavior and Sociobiology
• This is an interesting chapter, take a look at
  the diagrams and studies, but we will not be
  going into it this year in class

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Population Ecology

• Chapter 52

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Population Ecology

• Study of growth, abundance, and distribution of
  populations
• Basic Factors that affect Population Size
• Birth Rate
• Death Rate
• Immigration
• Emigration

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Factors that describe Population Abundance and
Distribution

• Population Size
• Population Density
• Dispersion
• Age Structure
• Survivorship Curves
• How do you think each of the above affect
  population abundance/distribution?

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• Population Size (n) number of individuals in
  the population
• Population Density total number of individuals
  per area (or volume) occupied
• Dispersion how individuals in a population are
  distributed. May be clumped, uniform, or random
• Age Structure description of the abundance of
  individuals at each age
• Rapidly growing populations have a larger
  proportion of population as younger
• Tiers of equal representation means stable or
  little growth populations

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Age Structure Diagram
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Survivorship CurveWhat does this graph tell you
about the different types of survivorship?
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• Survivorship Curves describe how mortality of
  individuals in a species varies during their
  lifetimes (ex humans)
• Type I curves Most individuals survive to
  middle age, but after that mortality is high
• Type II curves length of survivorship is random
  (likelyhood of death is same at any age) (ex
  squirrels)
• Type III curves Most individuals die young,
  with only relatively few surviving to
  reproductive age and beyond (ex oysters)

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Survivorship Curve
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Reproductive Episodes per Lifetime

• Semelparity
• Most of their energy is invested in a single
  large reproductive effort
• Ex Insects, Salmon, annual plants
• Iteroparity
• Produce fewer offspring at a time over a span of
  many seasons

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How fast do populations grow?

• Grow exponentially as population gets larger,
  it grows faster (more reproducing organisms)
• J-Shaped Curve

Population size
Can this continue forever?
Time
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Limits on the Environment

• Limiting factors will stop a population from
  increasing causes an S shaped curve.
• Examples
• Food, Shelter, Sunlight, Water
• Carrying Capacity the number of one species
  that an environment can support.

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Carrying Capacity
Population size
Time
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Biotic Potential

• Maximum growth rate of a population
• under ideal conditions
• Produces a J-shaped curve
• Following Factors Contribute to Biotic Potential
• Age at reproductive maturity
• Clutch Size ( of offspring)
• Frequency of reproduction
• Reproductive Lifetime
• Survivorship of offspring to reproductive
  maturity

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Limiting Factors

• Elements that prevent a population from attaining
  its biotic potential
• (Limits that effect population size and growth)
• Categorized as
• Density-Dependent Factors
• Density-Independent Factors
• Intraspecific competition reliance of
  individuals of the same species on the same
  limited resources

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Density-Dependent Factors

• Limiting effect becomes more intense as the
  population density increases
• Examples
• Parasites and disease (transmission rates
  increase with population density)
• Competition for resources (food, space, sunlight)
• Toxic effect of waste products

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Density-Independent Factors

• Factors occur independently of the density of the
  population
• Examples
• Natural disasters (fires, earthquakes, volcanic
  eruptions)
• Climate extremes (storms, frosts, drought)

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Population Growth Descriptions

• r (births deaths) / N
• r reproductive rate (growth rate)
• N population size at the beginning of interval
  for which the births and deaths are counted
• Example
• Population of size N 1000 had 60 briths and 10
  deaths over a one-year period, then r
  (60-10)/1000, or 0.05 per year
• DN / Dt rN births deaths

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• Intrinsic Rate of Growth maximum reproductive
  rate (births far outweigh deaths)
• If deaths exceed births, r will be negative, and
  the population size will decrease
• K represents carrying capacity (pop. is at
  carrying capacity when N K)
• 2 general patterns of population growth
• Exponential Growth
• Reproductive rate gt 0
• J-shaped curve
• Logistic Growth
• Limiting factors restrict size of population to
  carrying capacity

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r-selected vs. K-selected species

• Exponential and logistic growth patterns are
  associated with 2 kinds of life-history
  strategies
• r-selected species (Rapid Life History)
• K-selected species (Long Life History)

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r-selected (Opportunistic) Populations

• Organisms in unpredictable environments.
• Small bodies
• Mature rapidly (little parental care, if any)
• Reproduce early
• Short life spans
• Lots of offspring
• Examples
• mouse, mosquito, fly, weeds, etc.

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K-selected (Equilibrial) Populations

• Organisms in stable environments
• Population Size remains relatively constant (near
  carrying capacity, K)
• Large bodies
• Mature slowly
• Reproduce slowly
• Long life
• Few offspring
• Examples
• Human, elephant, horse, tree, etc.

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Population Cycles

• Describe fluctuations in population size in
  response to varying effects of limiting factors
• Some populations have regular boom and bust
  cycles.
• When Populations are
• Above Carrying capacity
• limiting factors will exert negative feedback on
  population growth
• Below Carrying capacity
• limiting factors will exert little negative
  feedback and population growth renews

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Human Population Growth

• Began exponential growth about 1000 years ago.
• Can it do so indefinitely?!?!?!
• Why or Why not?
• How was exponential growth possible for this long?

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Exponential Human Population Growth

• Made possible by
• Increases in Food Supply Domesticating animals
  and plants and improved technology in harvesting,
  etc.
• Reduction in Disease Advances in medicine
• Reduction in Human Wastes developing water
  purification and sewage systems
• Expansion of Habitat Improved housing,
  clothing, energy access has made this possible.
• These changes have greatly increased the carrying
  capacity of the environment
• How will things change in the next 1000 years?

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Community Ecology

• Chapter 53

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• Community Ecology is concerned with the
  interactions of populations
• Interspecific competition competition between
  different species

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Ways to resolve competition

• 1) Competitive Exclusion Principle (Gauses
  principle)
• Two species compete for exactly the same
  resources
• One is likely to be more successful and
  outcompetes the other
• The other organism is eliminated
• No two species can sustain coexistence if they
  occupy the same niche
• Gause tested by mixing two species of paramecium.

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Resource Partitioning
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• 2) Resource Partioning
• Species coexist in spite of apparent competition
• Occupy slightly different niches
• Slightly different resources or securing
  resources slightly differently minimizes
  competition and maximizes success
• Resources are divided
• Ex 5 species of warblers coexist in spruce trees
  by feeding on insects in different regions of the
  tree and using different feeding behaviors

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Character Displacement
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• 3) Character Displacement (niche shift)
• Due to resource partioning, certain
  characteristics may enable individuals to obtain
  resources more successfully
• Selection reduces competition and leads to a
  divergence of features
• Ex Two species of Finch live on 2 different
  Galapagos Islands and have similar beaks. On a
  third island, they coexist, but due to evolution
  the beak of each bird species is different and
  competition is minimized

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Fundamental Niche vs. Realized Niche
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• 4) Realized Niche
• Fundamental niche niche in the absence of
  competing species
• Realized Niche With competing species, both can
  coexist by occupying their realized niches.
• Part of their existence where niche overlap is
  absent
• Competition for resources does not take place
• Ex In experimental conditions, a species of
  barnacle can live on rocks exposed to full range
  of tides, but in natural environment it gets
  outcompeted in lower tide levels and the first
  species must survive in realized niche, higher
  tide levels.

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Predation

• True Predator Kills and eats other animals
• Parasite spends most/all of life living on
  anotehr organim (host) obtaining nourishment from
  the host by feeding on its tissues. (Host
  typically doesnt die)
• Parasitoid insect that lays eggs on a host
  (usually insect or spider). Eggs hatch and
  larvae obtain nourishment by consuming the
  tissues of the host (Host typically dies)
• Herbivore animal that eats plants

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Keystone Species

• Keystone species species that makes an
  unusually strong impact on community structure
  (impact is much larger than its own abundance)
• Keystone Predators can alter community structure
  by moderating competition among prey species
• Can maintain higher species diversity (starfish
  in intertidal zone) or can alter character of
  whole communities (beavers constructing dams)

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Symbiosis

• Two species that live together in close contact
  during a portion (or all) of their lives.
• Three forms of Symbiosis
• Mutualism
• Commensalism
• Parasitism
• What can you group remember about the different
  types of symbiosis?

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Mutualism

• Both Species benefit
• Ex
• Acacia trees provide food and housing for ants,
  ants kill insects or fungi found on tree

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Commensalism

• One species benefits while other neither helped
  nor harmed
• Ex
• Birds build their nests in trees
• Egrets gather around cattle. Birds eat insects
  aroused by cattle, cattle arent helped or hurt
• Pilot fish following sharks

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Parasitism

• Parasite benefits while the host is harmed
• Ex
• Tapeworms in the digestive tract of animals
  stealing nutrients from host

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Living Relationships
Type of Relationship Organism A Organism B Example
Commensalism
Mutualism
Parasitism Predator/ Prey

Spanish Moss/ Trees
benefits
neutral
Bee / Flower
benefits
benefits
harmed
Tick / Deer
benefits
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Coevolution

• The natural selection of characteristics that
  promote the most successful predators and the
  most elusive prey leads to coevolution of
  predators and prey.
• Coevolution in one species is a response to new
  adaptations in another species
• We will be looking at a couple important examples
  of coevolution

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1) Secondary Compounds

• Toxic chemicals produced in plants that
  discourage would-be herbivores
• Ex Tannins (found in oaks) and Nicotine (found
  in tobacco) are toxic to herbivores

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2) Camouflage (cryptic coloration)
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2) Camouflage

• Any color, pattern, shape, or behavior that
  enables an animal to blend in with its
  surroundings
• Benefits both prey and predator

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3) Aposematic Coloration (warning coloration)

• Conspicuous pattern or coloration of animals that
  warns predators that they sting, bite, taste bad,
  or otherwise should be avoided

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4) Mimicry

• When 2 or more species mimic one another in
  appearance
• Mullerian mimicry several animals with same
  special defense mechanism share same coloration
  (bees, yellow jackets, wasps)
• Batesian mimicry Animal without special defense
  mechanism mimics coloration of animal that
  possesses defense (flies that have coloration to
  mimic bees)

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Ecological Succession

• Natural change in species replacements that take
  place over time
• As succession progresses, species diversity
  (total of species) and total biomass (total
  mass of all living organisms) increase
• This increase results in the Climax Community
• Residents species can create a disturbance in
  their community in some of the following ways
• Changing the substrate texture, soil pH, soil
  water potential, and available light also
  adjusted through crowding

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Succession Continued

• Occurs in stages
• Decades or even centuries to see this process
• Primary Succession Colonization of new sites by
  communities of organisms. Ex. Lava flow

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Pioneer Species

• The first species to occur in an area after
  primary succession has occurred.
• Typically r-selected species
• Ex Lichen

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From Pioneer Species to Climax Community

• On Rock
• Lichen attach to rock and secretes acid that help
  erode rock into soil
• Soil accumulates and bacteria, protists, mosses,
  and fungi appear followed by insects and
  arthropods
• Grasses, herbs, weeds, and other r-selected
  species show up
• Begin to be replaced by K-selected species
• On Sand not much different, but specialized
  grasses colonize and stabilize sandy area

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Climax Community

• Stable, mature community that undergoes little or
  no change in species.

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Secondary Succession

• Sequence of community changes that takes place
  after a community is disrupted by natural
  disasters or human actions
• Occurs in an area that previously contained life
• Less time to reach a climax community here again
  because life already existed.
• Examples Forest Fires, hurricanes

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Primary or Secondary Succession?
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Primary or Secondary Succession?
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Ecosystems

• Chapter 54

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Trophic Relationships

• Primary Producers (autotrophs)
• Primary Consumers (heterotrophs)
• Secondary Consumers
• Tertiary Consumers
• Detritivores
• Consumers that obtain their energy by consuming
  dead plants and animals (includes fungi,
  bacteria, nematodes, earthworms, insects, and
  scavengers)

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Food Chains

• Pathway showing how MATTER and ENERGY move
  through the ecosystem.
• Some energy is lost at each link

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Food Web

• Expresses all possible feeding relationships in a
  community

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Ecological Pyramids
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Ecological Pyramids (contd)

• Shows energy used in an ecosystem
• Models the distribution of matter and energy
  within an ecosystem
• Several different types of ecological pyramids
• Pyramid of Energy
• Pyramid of Biomass
• Pyramid of Numbers

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Where does all the energy go?

• Ecological efficiency Proportion of energy
  represented at one trophic level that is
  transferred to the next level
• Only about 10 of energy is transferred from one
  energy level to the next!
• Where does the other 90 go?
• Consumed by the individuals metabolic activities
• Why are most food chains only 3 to 5 links long?
• What would be the most effective way to feed the
  world?
• Why are most animals used for food or work
  primary consumers?

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Pyramid of Net Productivity
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Biogeochemical Cycles

• Describe the flow of essential elements from the
  environment to living things and back
• In studying the cycles, you need to know the
  following
• Major Storage Locations (reservoirs)
• Process in which each element is incorporated
  into organisms (assimilation)
• Process in which it returns to the environment
  (release)

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Hydrologic Cycle (water cycle)
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Water Cycle
Reservoirs Assimilation Release
Oceans Air Groundwater Glaciers Evaporation, wind, and precipitation move water from oceans to land Plants absorb water from the soil Animals drink water or eat other organisms Plants transpire Animals and plants Decompose
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Carbon Cycle
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Carbon Cycle
Reservoirs Assimilation Release
Atmosphere (CO2) Fossil Fuels (coal, oil) Peat Organic Material (cellulose) Plants use CO2 in photosynthesis Animals consume plants or other animals CO2 released through respiration and decomposition CO2 released by burning of fossil fuels
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Nitrogen Cycle
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Nitrogen Cycle
Reservoirs Assimilation Release
Atmosphere (N2) Soil (NH4, NH3, NO2-, NO3-) Plants absorb nitrogen as NO3- or as NH4 Animals eat plants or other animals Nitrogen Fixation (N2 to NH4 by prokaryotes and N2 to NO3- by lightning and UV Nitrification (NH4 ? NO2- ? NO3- by nitrifying bacteria Denitrifying bacteria Detrivorous bacteria (ammonification) Animal excretion
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Phosphorus Cycle
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Phosphorus Cycle
Reservoirs Assimilation Release
Rocks Erosion transfers phosphorus to water and soil Plants absorb inorganic PO4-3 from soils Animals obtain organic phosphorus by eating plants or other animals Plants and animals release P when they decompose Animals excrete P in their waste products
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Human Impact on the Biosphere

• Is human impact on the biosphere good or bad?
• What types of human impacts are damaging the
  biosphere?
• Exponential population growth
• Destruction of habitats for Ag and Mining
• Pollution from industry and transportation

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Greenhouse Effect

• Burning of fossil fuels and forests increases CO2
  in the atmosphere
• Increased CO2 traps heat in the earths
  atmosphere
• Global temperature begin to rise which would lead
  to
• Raised Sea levels (melting of more ice)
• Decreased Ag output (affecting weather patterns)

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Ozone Depletion

• Ozone layer is upper atmosphere when UV reacts
  with O2 to form O3
• Ozone absorbs UV and prevents it from reaching
  the surface of earth where it can damage DNA of
  plants and animals
• Various air pollutants (ex CFCs) enter upper
  atmosphere and break down ozone
• Thinning ozone creates ozone holes

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Acid Rain

• Burning fossil fuels and other industrial
  processes release air pollutants
• SO2 and NO2 react with water vapor to produce
  sulfuric and nitric acid
• Acids return to earths surface and kill plants
  and animals in lakes and rivers

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Desertification

• Overgrazing of grasslands that border deserts
  transform grasslands into deserts
• Agricultural output decreases or native species
  are lost

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Deforestation

• Clear-cutting of forests causes erosion, flooding
  and changes in weather patterns.
• Slash-and-burn method of tropical rain forests
  (for Ag) increases atmospheric CO2
• This technique destroys nutrients and some soils
  can only support Ag for 1 or 2 years

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Pollution

• Air, water, and land pollution contaminate the
  materials essential to life
• Many pollutants dont degrade and remain in
  environment for decades
• Some toxins gets passed down the food chain
  effecting all organisms along the way
  biological magnification

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Reduction in Species Diversity

• Due to human activities, plants and animals are
  apparently becoming extinct at a faster rate than
  the planet has ever experienced
• Many of these species could have possibly become
  useful to humans as medicines, foods, or
  industrial products.

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Conservation BiologyChapter 55

• Another interesting chapter in what is being done
  to lessen human impact on the globebut we will
  not be going into it