Chapters 35

1
Chapters 3-5

• Communities,
• Population Biology, Biological Diversity
  Conservation

Big Idea How much can ecosystems handle before
we screw them up permanently?
2
Living in the Community

• Community collection of interacting populations
• Limiting Factors environmental factors that
  affect an organisms ability to survive in its
  environment
• Can be living food availability, predators
• Can be non-living temperature, water, sunlight
• Can affect a population directly or indirectly
• For instance, food availability will affect a
  herbivore and the carnivore that eats the
  herbivore

3
Ranges of Tolerance

• Tolerance the ability of an organism to
  withstand fluctuations in biotic and abiotic
  environmental factors
• Each organism has a specific range that it can
  survive in for a specific factor
• Ex catfish can tolerate warm water with little
  oxygen, while bass or trout cannot

Pg. 66 of book
Organisms Absent Zone of Intolerance
Organisms Infrequent Zone of Physiological stres
s
Greatest Number of Organisms Optimum Range
Organisms Infrequent Zone of Physiological Stres
s
Organisms Absent Zone of Intolerance
Population
Range of Tolerance
Low
High
4
Succession

• Lets say you no longer cut your lawn. What
  would happen with sufficient water?
• 1. The grass gets taller weeds start to grow.
  The area resembles a meadow.
• 2. Later, bushes grow, trees appear and different
  animals enter the area to live.
• 3. The bushes and trees change the environment
  less light reaches the ground. The grass slowly
  disappears.
• 4. Thirty years later, the area is a forest.

5
Succession

• The orderly, natural changes and species
  replacements that take place in the communities
  of an ecosystem
• Primary Succession the colonization of new
  sites by communities of organisms
• Pioneer Species the first species in an area
• Ex Lichen (a combination of fungus and algae)
  grows readily after a volcanic eruption
• Lichens break up rock slowly and help soil
  accumulate
• Slowly, more things are able to live in the
  environment
• Climax Community mature community that
  undergoes little or no change
• Ex Deciduous forest

6
Secondary Succession

• The sequence of community changes that takes
  place after a community is disrupted by natural
  disasters or human actions
• Occurs on land that already has soil
• The pioneer species will be different and the
  community will climax in a shorter time
• Example Yellowstone burned in 1988
• Wildflowers came back first, then grasses, ferns
  and pine seedlings

7
Biome

• A biome is a large group of ecosystems that share
  the same type of climax community
• There are terrestrial biomes (tundra, taiga,
  desert, grassland, temperate forest, rain forest)
• There are aquatic biomes (marine, estuaries,
  freshwater)

8
Review

• What are the two kinds of limiting factors?
• What is a range of tolerance? Give an example.
• What is primary succession?
• What is secondary succession?
• What is a biome?
• What is a pioneer species?

9
Chapter 4 Population Biology

• Population Growth an increase in the size of a
  population over time
• All populations start off growing relatively
  slowly (relative to their capacity to reproduce)
• If resources are not limited, all populations
  will grow exponentially (a J curve)

10
Realistic Population Growth

• Resources are never unlimited
• Populations will reach a carrying capacity the
  number of organisms of one species that an
  environment can support
• Populations follow an S-shaped growth curve

Pg. 94 of book
Carrying Capacity if population gets bigger,
organisms die
--------------------------------------------------
-------------------------------------------------
Carrying Capacity
Leveling Off competition, limited resources
slow growth, limiting factors
Fluctuations birth and death rates fluctuate
with competition and resources
Beginning Growth - Population slowly increases
Rapid Growth exponential growth
11
Patterns of Population Growth

• Some organisms reach their carrying capacity
  faster than others
• This is due to their reproductive patterns
• Environmental Conditions
• Ideal ranges
• In general, organisms that are small and mature
  rapidly reach carrying capacity faster
• Organisms that are large and mature slowly, reach
  a carrying capacity slower

12
Environmental Limits to Population Growth

• Density-Dependent Limiting Factors have an
  increasing effect as the population increases
• Ex disease, competition, parasites, food
• Ex How does predation effect population sizes?
• Density-Independent Limiting Factors affect all
  populations, regardless of their density
• Most are abiotic factors such as temperature,
  storms, flood, drought, habitat destruction

13
Density-Dependent Limiting Factors

• Competition increases within species as
  population gets too big.
• Over food, water, territory, mates, etc.
• Can you see this in a human population?

14
Density-Dependent Limiting Factors

• Crowding Stress as populations increase in
  size, individual animals begin to exhibit
• Aggression
• Decrease in parental care
• Decreased fertility
• Decreased resistance to disease
• Can you see this in a human population?

15
Review

• What conditions must be met for exponential
  growth?
• What pattern do populations follow in reality?
• What determines how fast a population reaches its
  carrying capacity?
• Give 3 density-independent limiting factors.
• How can crowding and stress limit a population?
• Describe the relationship between predators and
  prey.

16
Demographic Trends

• Demography the study of human population growth
  characteristics
• i.e., growth rate, age structure, geographic
  distribution
• Humans reduce negative environmental effects on
  our population
• i.e., eliminating competitors, increasing food
  production, controlling diseases
• Human Population (see pg. 100 in book)
• 1 A.D. around 1850 slow growth
• After 1850-present exponential growth (J-curve)

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Realistic Population Growth

• Where are humans on this curve?
• What will eventually have to happen?

Pg. 94 of book
Carrying Capacity if population gets bigger,
organisms die
--------------------------------------------------
-------------------------------------------------
Carrying Capacity
Fluctuations birth and death rates fluctuate
with competition and resources
Beginning Growth - Population slowly increases
Leveling Off competition, limited resources
slow growth
Rapid Growth exponential growth
19
Birth and Death Rates

• Death Rate the number of deaths per 1000 people
  in a given year
• Affected by life expectancy, diseases in area,
  stress, etc.
• Difference in Africa and U.S.?
• Birth Rate the number of live births per 1000
  people people in a given year.
• Fertility rate is a large influence here
• Difference in Africa and U.S.?

20
Population Growth Rate (PGR)

• Immigration movement of individuals into a
  population
• Emigration movement from a population
• Population Growth Rate (Birthrate Immigration
  Rate) - (Death Rate Emigration Rate)
• Or, for convenience
• PGR Birthrate - Death rate
• When birthrate equals death rate, the population
  isnt growing
• As long as the PGR is positive, the population
  will continue to grow

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22
Doubling Time Age Structure

• Doubling Time - the time needed for a population
  to double in size
• Doubling Time (in years) 70/annual percent
  growth rate
• What is happening to the world doubling time?
• Age structure refers to the proportions of a
  population that are at different age levels
• If a population has many young members, it will
  mostly likely grow rapidly
• If a population has equal numbers of ages, it is
  stable
• Look page 103 in book
• These demographics do not influence world
  population, but do show movement from or to urban
  areas, countries, etc.

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Ecology and Growth

• Population needs differ throughout the world
• Some populations have competition for food,
  water, etc.
• Some population are more concerned about the
  health of their citizens
• When populations grow rapidly, there is often
  competition for resources
• Lead to stress, contamination, etc. that lead to
  disease and affect stability of populations

25
Review

• How do humans change the rules in demography?
• How do birth rates and death rates influence
  population growth?
• How do you calculate population growth rate?
• What is a populations doubling time?
• How do population needs differ around the world?

26
Biological Diversity

• Biodiversity refers to the variety of life in an
  area
• Most common measure is the number of species that
  live in a certain area
• Terrestrial biodiversity tends to increase as you
  move towards the equator (or in isolated warm
  regions)
• 2/3 of all land species on Earth are in tropical
  regions
• The size of the area also affects biodiversity
• Larger areas tend to be more diverse (unless
  other things prevent or encourage life)

27
Importance of Biodiversity

• Organisms are adapted to live together in a
  community
• If you take one away, there are consequences to
  the rest
• Biodiversity brings stability to an ecosystem
• More resources, interactions, etc.
• When a population utilizes more than one
  resource, it will be ok if one of them disappear
• Biodiversity is important to humans
• Oxygen to breath, remove CO2
• Diverse diet / Better crops (resistance)
• Building materials
• Possible pharmaceuticals

28
Loss of Biodiversity

• Extinction the disappearance of a species when
  the last of its members dies
• Since 1980, almost 40 species of plants and
  animals have gone extinct in the U.S.
• Can be natural or human-caused
• Threatened Species when the population of a
  species begins declining rapidly
• In the US sea otters, loggerhead turtles, bald
  eagle
• Endangered Species population numbers so low
  that extinction is possible
• In the US California Condor, Florida manatees

29
Threats to Biodiversity

• Habitat loss the biggest threat
• Take away resources for life
• Habitat fragmentation separation of wilderness
  areas from other wilderness areas
• Roads leads to less biodiversity
• Animals that migrate or need large areas to hunt
• Climates can change (take away shade)
• Edge Effect the different conditions along the
  boundaries of an ecosystem

30
Threats to Biodiversity

• Habitat Degradation the damage to a habitat by
  pollution
• Air, Water, or Land
• Air Pollution
• Burning fossil fuels is the greatest source of
  air pollution
• Acid Precipitation sulfur dioxide from burning
  coal and nitrogen oxides from automobile exhausts
  combine with water
  vapor
• Leaches nutrients from the soil
• Damages plant tissues
• Alters pH of lakes
• Ozone layer damage CFCs break down 03
• Increased skin cancers
• Possible cause for amphibian population decreasing

31
Threats to Biodiversity

• Water Pollution
• Fertilizers and animal wastes carried by runoff
• Causes algal blooms
• These algae die, decay and remove oxygen from the
  water
• Silt from erosion clogs gills, blocks sunlight
• Detergents, metals, industrial chemicals from
  runoff
• Debris in oceans and lakes

32
Threats to Biodiversity

• Land pollution
• Trash the average American produces about 1.8
  kg of solid waste daily 657 kg/yr
• Destroy habitats and pollute areas
• Pesticides, etc. can also lead to habitat
  degredation
• DDT

33
Threats to Biodiversity

• Introduction of Exotics
• Exotic species organisms that are not native to
  a particular area
• Can grow at an exponential rate due to a lack of
  competitors and a lack of predators
• Take over niches of native
  species or replace the
  species
• Sea lamprey in Great
  Lakes after Erie Canal
• Goats on Santa Catalina Island

34
Section 1 Review

• What are two reasons for a species to become
  threatened or endangered?
• Explain how land that gets broken up can
  contribute to loss of species diversity.
• What is an edge effect? Explain how changes in
  an ecosystems edges can affect organisms.
• How can exotic species affect populations of
  native species?

35
Conservation Biology

• Conservation Biology is the study and
  implementation of methods to protect
  biodiversity.
• Natural resource conservation - natural resources
  are those parts of the
  environment that are useful or
  necessary for living
  organisms.
• Species conservation - protecting
  species from extinction and
  preserving biodiversity

36
Legal Protection of Species

• 1973, the U.S. Endangered Species Act made it
  illegal to harm any species on the endangered or
  threatened list
• Illegal for federal agencies to
  fund any
  project that would
  harm these species
• The Convention on International Trade in
  Endangered Species (CITES)
• Established lists of species for which
  international trade is prohibited or controlled
• Honored by 120 countries

37
Preserving Habitats

• One way is to create national parks
• First one in US was Yellowstone
• Originally this was to preserve the geology
• Protects natural environments and
  provides habitats
  for many organisms

38
Habitat Corridors

• Protected strips of land that allow the migration
  of organisms from one wilderness to another
• Isolated populations inbreed too much

39
Sustainable Use

• In National Parks, the land is managed
• This philosophy strives to enable people to use
  natural resources in ways that will benefit them
  and maintain the ecosystem
• Some grazing
• Harvest fruits
• Hiking, camping, etc.

40
Preservation Programs

• Captive Breeding followed by Reintroduction
  Programs
• Release organisms into area where the species
  once lived
• Ex black-footed ferret
• Ex brown pelican after DDT
• Seed banks for threatened and endangered plant
  species

41
Section 2 Review

• Describe the U.S. Endangered Species Act.
• Why is it difficult to reintroduce species that
  have been captive bred?
• What is sustainable use and how does it influence
  Utah?