PowerPoint Presentation

							       Chapter 4:
    Population Biology
 What is a population?
 What is exponential population
  growth?
 What is biotic potential?

 What is logistical population growth?

 What is carrying capacity?

 What limits a population’s size?
  Population Density
# organisms in an area
How many mice are in the following population?


                 Estimate!



                   Ready

                    SET


                   Go!
How many did you count?

  What is the best way to count
              them?
        SAMPLING
     Population Sampling
   Usually, the population is
    too large or mobile for the
    researcher to attempt to
    count all of its members.
    – A small, but carefully chosen
      sample can be used to
      represent the population.
    – The sample reflects the
      characteristics of the
      population from which it is
      drawn
So how could we estimate this population
without counting EVERY mouse?
          Population Size
   Factors that affect:
    – 1. Natality (+)
    – 2. Mortality/Fatality (-)
    – 3. Immigration (+)
    – 4. Emigration (-)
    What underlying factors may cause these
      to increase or decrease in an area?
    Changes in Population
            Size
   Birth rate (natality) & Death rate (fatality/mortality)
    – Changes over time are calculated
         EX: If the birth rate in 1990 was 50 per 100,000
          moose and in 2000 it was 150 per 100,000
          moose, what can we say about the birth rate
          over this time period?
           – IT TRIPLED!
    Carrying Capacity (K)
   Maximum # of organisms in a
    population supported by an
    ecosystem’s resources/limiting factors
    – Effected by factors such as the amount
      of:
        Food,   water, space, etc…
    – Can change when these factors change
        EX:   more food = higher carrying capacity!
  Environmental
    Limits to
Population Growth
Factors regulating the size of a
          population

LIMITING FACTORS: Factors
that limit how many organisms
 and ecosystem can support.
        Limiting Factors
   Definition?




Any biotic or abiotic factor
that causes population size
to decrease and influences
what can live where
 What factors limited
the growth of our lima
       beans?
   What contributes
    to the fluctuation
    of the population
    when it reaches
    carrying capacity?
What factors would limit
 these communities?
             Classification of
             Limiting Factors
   Density-dependent                   Density-independent
    –   Nutrients                        – Temperature
    –   Space                            – Natural Disaster
    –   Disease                          – Habitat
    –   Food                               Degradation/Disruption/
    –   Parasitism                       Destruction
    –   Predation                        – MAJOR CHANGES in
    –   Competition                        ABIOTIC FACTORS
            Intraspecific
               – Same species
            Interspecific
               – Different species
    Organism Interactions
     Density Dependant
   Predation
   Competition
    – Both types
 Parasitism
 Crowding/stress/

disease
        Predation – Density
            Dependent
   What can be said
    about this graph?
   Why are predators
    necessary?
   Why don’t prey
    become extinct?
Competition – Density Dependant
 •Competitive Exclusion Principle – No 2
 organisms can occupy the exact same
 niche in the exact same habitat at the
 exact same time
    Competition: Who ultimately
              “wins”?
 The species best adapted to the niche!
 What is a NICHE????
         Two types of
         competition:

 Intraspecific- between same species
 Interspecific-between different species
        Competition – Density

                        Dependant food added
    When either species was cultured alone — with fresh
    regularly — the population grew exponentially at first and then
    leveled off.
   When the two different species were cultured together, P.
    caudatum proved to be the weaker competitor. The population of
    P. aurelia reached a plateau, but so long as P. caudatum
    remained, this was below the population density it achieved when
    grown alone.
   Intra or Inter?
      Limited Resources -
      Density Dependent
   Here is a dramatic
    example of how
    competition among
    members of one
    species for a finite
    resource — in this
    case, food — caused
    a sharp drop in
    population.
   The graph shows a
    population crash; in
    this case of reindeer
    on two islands in the
                            Inter or Intra?
    Bering Sea.
      Natural Disasters –
     Density Independent
   Decline in the population of
    one of Darwin's finches on
    Daphne Major, a tiny (100-
    acre) member of the
    Galapagos Islands.
   The decline (from 1400 to
    200 individuals) occurred
    because of a severe
    drought that reduced the
    quantity of seeds on which
    this species feeds.
   The drought ended in 1978,
    but even with ample food
    once again available the
    finch population recovered
    only slowly.
   Why not Density
    Dependant?
         Logistic Growth
          The “S” Curve
This graph shows
logistical growth


What causes
growth to slow?


ALL growth will
eventually become
logistical or
crash….why?
Population Growth Curves
    Explain what is happening to the
     populations below:
    Exponential Growth
      The “J” Curve

When does this
occur?
•With temporarily
unlimited resources
•With reproduction at
the rate of biotic
potential
  Biotic Potential =
Reproductive Potential
   Reproducing as fasts as
    biological possible
   Rate at which a population
    could grow if it had unlimited
    resources
   Reproducing at biotic potential
    leads to exponential growth
   Humans….
    – Biotic potential on average = 50-
      60 children/woman!
    – Why don’t women have this many
      kids?!?!
They only reproduce part of the year




                         NOTE:
                         gestation ~1
                         week
                         development ~12
                         days
AKS Bio 11c) Relate environmental
conditions to successional changes in an
ecosystem
Succession – The series of ecological
changes in an ecosystem over time




2 Types – Primary & Secondary
From Pioneer Stage  Climax Community
Ecological Succession
   A series of predictable changes that
    occurs in a community over time.
    – Primary Succession
    – Secondary Succession
Ecological Succession
      Overview
    Primary Succession
 No previous
  ecosystem
 Soil must be
  created
 From
  nothing to
  ecosystem
 Pioneer
  species –
  bacteria,
  algae, moss,
  lichen
                        Pioneer
                        Species

   Species that colonize areas

   Bacteria, Mosses, Lichen, Algae -
    brief life cycles

   Improve conditions for species that
    replace them

   Their breakdown makes soil - primary
     Secondary Succession
 An existing
  ecosystem is
  disturbed
 Soil and some
  organisms may
  remain
 Pioneer species
  such as small
  grasses
  repopulate first
    Secondary Succession
 Can change type of
  community/ecosystem
 From lake to forest
  ecosystem
 What might cause
  this?
 How long might this
  take?
      Climax Community
   THE ULTIMATE RESULT OF SUCCESSION!
   Stable array of species that persists relatively
    unchanged over time
               Climax Community
 Ecological succession will occur until a climax
  community is reached.
    – A climax community is when the plant life has
      reached a stable state
   The climax community will continue until
    there is a disturbance.
    – Natural disasters
    – Human Impact
     What would this be?
   A volcano erupts in the ocean. When
    the lava cools, a barren rock is made.
    The rock becomes inhabited by
    mosses and lichen which over time will
    produce soil. This is an example of
    ______________ succession.
    – PRIMARY
        WHY?
     You Tube Clip Chris
       Brown style….
   http://www.youtube.com/watch?v=rzE6
    BNNLew0
The Human Population




 Figure 4.10 pg 104
    Human Population Growth
 What influences growth in the human
  population?
 Change in density dependent limiting
  Factors?
 Change in density independent limiting
  factors?
 Are all countries growing
  exponentially?
            Demography
            Vocabulary




   Age Structure
   Immigration
   Emigration
   Natality & Fatality data
     How does each effect population size?
    Age Structure Pyramids
   These pyramids compare the age structure of the populations of France
    and India in 1984. The relative number (%) of males and females is shown
    in 5-year cohorts. Almost 20% of India's population were children — 15
    years or less in age — who had yet to begin reproduction. When the
    members of a large cohort like this begin reproducing, they add greatly to
    birth rates. In France, in contrast, each cohort is about the size of the next
    until close to the top when old age begins to take its toll.
    Age Structure Pyramids
   These population pyramids show the baby-boom
    generation in 1970 and again in 1985 (green ovals).
   Profound changes (e.g. enrollments in schools and
    colleges) have occurred — and continue to occur — in
    U.S. society as this bulge passes into ever-older age
    brackets.
Do you know which
countries have the
highest population?

 Can you name the top 5?
Link
to
list
A Few more…
Who’s the LEAST populous?

  Let’s keep going down the list…
Human Population:
What Does Bill Nye
Have to Say About
      It……

 Let’s take a look at some
     human population
      demographics…
   Human Impact

  How are humans affecting
ecosystems all over the Earth?
     Biodiversity
   Refers to the
    variety of life
     in an area
    Why is Biodiversity
  important? It’s not just
  about the aesthetics…
Life depends on life…
     *brings stability to an ecosystem
     *living things create niches for other
           living things
     *symbiotic relationships can be
           established or maintained
     *effective food webs can be
  established          or maintained
          Human Impact
   Importance to
    nature –
    biodiversity
Importance to humans?
 Production of oxygen and carbon
  dioxide
 Diet

 Prevention of starvation

 Cross-breeding to make stronger,
  hardier organisms
 Materials for clothes, furniture,
  buildings
 medicines
           Loss of Diversity
   Extinction of Species
   Endangered Species
   Threatened Species
    – Believe it or
      not….99.9% of all once
      living species are now
      extinct!
    – How big is the problem?
     Loss of Biodiversity
    Extinct: entire species has died out and can
     never return


Dodo Bird
Last confirmed
sighting in
1662.
Thought to be
extinct by
1690.
     Loss of Biodiversity
   Endangered: species in immediate
    danger of becoming extinct




    Grizzly Bear
     Loss of Biodiversity
   Threatened species: species are likely
    to become endangered in the future



                                    endangered
                                    if conditions
                                    surrounding
                                    them begin
                                    to or
                                    continue to
Source: http://ecos.fws.gov/tess_public/StateListing.do?state=all = updated daily
Source: http://ecos.fws.gov/tess_public/StateListing.do?state=all = updated daily
Monday, Sept. 14, 2009
 Threats to
Biodiversity
    Threats to Biodiversity

 1.Invasive Species
 2.Habitat Destruction

 3.Habitat Fragmentation
    – Biotic Issues
    – Abiotic Issues
   4.Habitat Degradation
    – Air Pollution
    – Water Pollution
    – Land Pollution
       1. Invasive Species
   Non-native
    organisms that
    “move-in” to a
    particular area
   There can be a
    lack of competitors
    = exponential
    growth
   Out-compete
    natives for
    resources
   Can take over the
    niches of native
    species
Kudzu
Invasive Species
  The Nutria…
         Other Threats to
           Biodiversity
   2. Habitat loss
             *deforestation
             *clear-cutting grasslands
             *draining wetlands
   3. Habitat fragmentation
             *roads, fences
             *makes it difficult for species to re-
                          establish themselves
             *can change climate
             *can lead to edge effects
 4. Habitat degradation
           (damage to habitat by
     pollution)
*3 types of pollution: water, land, air
       Chemical Pollution
            Cycle
   Pollution added to the environment will
    cycle & ultimately reach humans:
    – EX: Chemicals are:
      1. Dumped – land/water  river/lake/ocean

      2. Enter the food chain

      3. Harm the aquatic & terrestrial life

      4. Threaten humans
            Water Pollution
   Additions of solid or liquid waste that is not
    naturally occurring

Ex. Excess fertilizer and
 animal waste wash into
 streams, rivers, lakes,
 ponds, and oceans cause
         ALGAL BLOOMS
         Land Pollution
   Trash, garbage, and litter
       *average American produces ~1.8
    kg of solid waste daily
     Let’s talk about 4
    HUGE human impact
     global problems…
 Biomagnification
 Ozone layer

 Acid Rain

 Earth’s temperature
        BIOMAGNIFICATION
   A concentration INCREASE in a
    chemical as it moves up the trophic
    levels
   WHY?
   EX: DDT, Mercury
Biomagnification – Where less is more
•Put on your name tag – who are you?
•Populations? Community? Ecosystem?
•What is the relationships of these organisms?
•Food web: birds can eat fish & shrimp; fish can
eat shrimp and algae; shrimp can eat algae; what
about algae?
Biomagnification – Where Less is More
•Problem: DDT has reached the ocean habitat of
your organisms and has entered the food chain in
low, non lethal levels
•Each organism has a different exposure –
   •Algae – 1 beans (PP)
   •Shrimp – 2 beans (PP)
   •Fish – 3 beans (PP)
   •Bird – 0 beans*
Biomagnification – Where Less is More
•Organisms “swim” around holding pesticide
particles in the left hand
•When you hear the sound, find the organism closest
to you, introduce yourself and determine any feeding
relationship
•To “eat” an organism, high five that organism with
your right hand (transfer energy!)
•The organism preyed upon gives the predator
his/her beans and sits down. The predator keeps
“swimming”
At the end of the simulation, if you are still “alive”
count the number of DDT particles you have.
If you “survived” what are the effects of the
pesticide on you?
Data Table: Pesticide Effects by Concentration
 Organism      3 PP           4 PP               5 PP             6 PP or greater
 Algae         inability to   cell wall          organism death
               reproduce      damage                                  --------
 Shrimp        no effect      softening of the   offspring        organism death
                              exoskeleton        develop with
                              (shell)            fewer legs
 Fish          no effect      mutations in       kidney damage    tumor
                              egg cells                           formation
 Bird          no effect      no effect          softening of egg problems with
                                                 shells           migration
                                                                  patterns and
                                                                  mating
                                                                  behaviors
     OZONE DEPLETION
   Ozone (O3) Depletion
    – O3 forms a “good layer”
      around the Earth
    – CFC release is breaking
      down the protective ozone
      layer                   ●
          CFC’s are used in refrigeration
           equipment
    – UV rays increase skin
      cancers & other cell
      mutations to plants &
      animals!
Figure 54.27a Erosion of Earth’s ozone shield: The ozone hole over the
                              Antarctic
    Ozone Depletion –
    What’s Been Done?
 CFC’s banned in most 190 countries in
  the 1970’s
 This is a success story!
     ACID RAIN/PRECIPITATION
   Acid Precipitation
     – rain, snow, dew or fog
     – Created when gases
       such as nitrogen oxide
       (NO2) and sulfur oxide
       (SO2), come from the
       burning of fossil fuels
       (coal and oil)
     – They react in the
       atmosphere with
       sunlight to produce
       acids…
           nitric and sulfuric acid
    – These acids dissolve in
      water to become acid
      precipitation
How is Acidity Measured?
 Acidity is measured in
  units called pH.
 The pH scale = 0 to 14
    – pH 7 indicates neutral
    – higher pH numbers =
      alkalinity (base)
    – smaller numbers = acid

       We’lldo more on pH in the
        “Biochemistry” chapter
    Natural Acid Precipitation
   CO2 combines with
    water to form a weak
    acid
    – H2CO3 (carbonic acid)
   But we are adding to
    the problem…
    – by adding nitric and
      sulfuric acids
     Look at the “clean
     rain” – it’s already
     slightly acidic???
     Effects of Acid Precipitation
• In Japan, rain which registers pH 5.6 or less is considered acid rain;
  some 80-90% of the rain that falls in Japan in a year is acid rain.
• In Japan, acid rain with acidity equal to lemon juice has been
  observed at Mount Tsukuba in 1984 (pH 2.5) and at Kagoshima in
  1987 (pH 2.45). The problem is even more serious in North America
  and Europe. In those regions, forests are withering and lakes
  becoming uninhabitable to fish, and stone structures such as buildings
  and bronze statues are being damaged by corrosion.




                     1970                   1985
      Acid Rain – What’s
         Been Done?
 Lower NOx and SOx emission fuels &
  technologies for cars
 Legislation initiatives for businesses
  with low NOx and SOx emissions
 Reduced reliance on coal electric
  power
    – Hydroelectric
    – Nuclear
                 Climate Change
   “The Greenhouse Effect”
    – Fossil fuels give off lots of CO2
        This   builds a blanket around the earth
 It is predicted that the Earth temp. will
  increase ~50C before 2050 = Ice age???
 Greenhouse gases slow/stop the
  escape of heat from Earth’s surface
        Global Warming
   Long-term increase in the temperature
    of Earth’s lower atmosphere
   CO2 – blue
   Temp – red
    Carbon Dioxide
Increase = BAD NEWS!
   Carbon dioxide levels fluctuate seasonally

   The average level is steadily increasing

   Burning of fossil fuels & deforestation are
    contributing to the increase
       Other “Natural”
      Greenhouse Gases
   Methane - produced by bacteria,
    termites, cows, locked in glaciers and
    YOU!
   Nitrous oxide - released by bacteria,
    fertilizers, and animal wastes
     Global Warming –
    What’s Been Done?
 Better fuels and technologies for
  combustion in cars and industry
 Research into oceanic pumping of
  CO2
 Algae “scrubbers” on smokestacks

 Legislation & conferences – Kyoto
  Protocol
 Green initiatives in society
                Conservation
Political Initiatives
 Lay Down The Law
  –   National Parks Act - 1916
  –   Clean Air Act - 1970
  –   Clean Water Act - 1972
  –   1973 = US Endangered
      Species Act
          Made it illegal to harm any
           species on the endangered
           OR threatened list
             – Including changing an
               ecosystem where the
               species lived
           Conservation
   Nature preserves
    – Protects entire communities/ecosystems
        Conservation
 Reintroduction Programs
 Captivity Breeding


Example:
The Ginkgo Tree
would probably
be extinct if it
were not for
Chinese monks
keeping it in
captivity around
temples
          Conservation
   Sustainable use:
    – Use what you need, but don’t damage the
      ecosystem

                                 Is this a
                                 good
                                 example of
                                 sustainable
                                 use?