Ecology and Environmental Problems

1
Ecology and Environmental Problems

• Dr. Ron Chesser Lecture 2 -
• 22 Jan. 04
• Science, Decision-making processes, social
  systems society.
• READING
• Chapters 1 2

2
Can science ever really prove anything?

• Yes and no. It depends on what you mean by
  "prove".
• Theories may change as our abilities to observe
  (measure) improve.

3
What is Occam's Razor?

• Occam's Razor is the principle proposed by
  William of Ockham in the fifteenth century that
  "entities should not be multiplied
  unnecessarily".
• In more modern terms, if you have two theories
  which both explain the observed facts then you
  should use the simplest until more evidence comes
  along.

4
Science and the Secular Universe

• Science does not make moral judgments. One can
  not draw moral lessons from the laws of nature.
• Evolution in particular seems to suffer from
  this. At one time or another it seems to have
  been used to justify Nazism, Communism, and every
  other -ism in between.
• These justifications are all completely false.
  Similarly, anyone who says "evolution theory is
  evil because it is used to support Communism" (or
  any other -ism) has also strayed from the path of
  Logic.

5
What is Dogma?

• Dogma is a statement or concept that is presented
  as accepted theory or fact, but has not been
  rigorously tested.
• Dogma is usually widely accepted.
• Dogma is prevalent in science and society.

6
Faith vs Theory

• Faith, defined as belief that does not rest on
  logical proof or material evidence, does not
  determine whether a scientific theory is adopted
  or discarded.
• One does not question faith.
• A theory must be falsifiable''

7
Where is the Truth?

• There IS a truth. The universe behaves in a real
  way that may be difficult to observe, measure,
  and predict. We have two choices to explain the
  behavior of the universe
• To adhere to a stated belief without question
• To build hypotheses, experimentation, and
  theories that explain the observations
• Neither approach guarantees the truth is found.

8
Did Mendel cook the books?

• Gregor Mendel was a 19th Century monk who
  discovered the laws of inheritance (dominant and
  recessive genes etc.). More recent analysis of
  his results suggest that they are "too good to be
  true". It seems from Mendel's raw data that
  chance played a smaller part in his experiments
  than it should. This does not imply fraud on the
  part of Mendel.
• First, the experiments were not "blind". Deciding
  whether a particular pea is wrinkled or not needs
  judgement, and this could bias Mendel's results
  towards the expected. This is an example of the
  "experimenter effect".
• Second, Mendel's Laws are only approximations. In
  fact, in some cases inheritance is less random
  than his Laws state.
• Third, Mendel might have neglected to publish the
  results of failed' experiments. It is
  interesting to note that all 7 of the
  characteristics measured in his published work
  are controlled by single genes. He did not report
  any experiments with more complicated
  characteristics. Mendel later started experiments
  with a more complex plant, hawkweed, could not
  interpret the results, got discouraged and
  abandoned plant science.

9
Evidence, evidence, evidence

• If you have an idea, remember that the burden of
  proof is on you.
• Science is not easy. It is a demanding
  discipline that is governed by skeptics who
  require rigorous experimentation. (manuscripts,
  seminars, teaching, books)

• a

• b

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Scientific Manuscript

• Abstract (Summary)
• Introduction -- Description of the problem
  (observation). Statement of the Hypothesis(es).
• Methods and Materials Complete description of
  methods used and materials needed.
• Results Statement of results of methods.
• Discussion What the results likely mean.
  Support for or rejection of hypotheses.
• Acknowledgements Who helped in the study.
• Literature Cited Previously published
  manuscripts that the authors used to support or
  build their ideas.

11
Experimenter Effect

• Sometimes you see what you expect to see
• Sometimes you see what you want to see
• Sometimes you see what you are told to see
• Sometimes you see what you are paid to see

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How do you avoid Experimenter Effect?

• Blind Study
• Randomly assign samples where the experimenter
  doesnt know what the groups are
• No one is aware of results until end of study
• Group Shift
• Change the groups so that the experimenter
  thinks one group is the other
• Replicate Experimentation
• Different groups analyze the same samples

13
Science vs Technology

• Science is the search for knowledge through a
  systematic method of the study of variation
• Technology is the application of science to make
  products or processes

14
What Does Society Need?

• Advanced Education and Training
• Energy Resources
• Natural resources (materials)
• Transportation and Communication
• Industry, Finance and Technology
• People who passionately support and defend the
  society
• Mechanisms for making decisions (who/how)
• Judicial Police System (Crime Punishment)

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Especially since 1960, several developments have
dramatically reduced infant and child mortality
throughout the world

• the use of DDT to eliminate mosquito-borne
  malaria
• childhood immunization programs against cholera,
  diphtheria and other often-fatal diseases
• antibiotics.
• During the same period, the "Green Revolution"
  greatly boosted food output through the
  cultivation of new disease-resistant rice and
  other food crops, and the use of fertilizers and
  more effective farming methods.

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r intrinsic rate of increase
Growth there are more born than die.
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Models of population growth
Exponential growth Nt Nt-1 rNt-1
N0er0t

tgeneration rintrinsic increase rate Nt
population size at time t. Nt-1population size
in prior generation N0initial population
size eexponential r0ln(1r)
N
t
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Carrying Capacity
The theoretical number of individuals that can be
supported by the resources within an ecosystem.
20
Earths Resources

• we have already transformed or degraded 39-50 of
  the Earth's land surface (agriculture, urban).
• we use 8 of the primary productivity of the
  oceans.
• we have increased atmospheric CO2 concentration
  by 30
• we use more than half of the accessible surface
  fresh water
• over 50 of terrestrial nitrogen fixation is
  caused by human activity (use of nitrogen
  fertilizer, planting of nitrogen-fixing crops,
  release of reactive nitrogen from fossil fuels
  into the atmosphere)
• on many islands, more than half of plant species
  have been introduced by man on continental areas
  the fraction is 20 or more
• about 20 of bird species have become extinct in
  the past 200 years, almost all of them because of
  human activity
• 22 of marine fisheries are overexploited or
  depleted, 44 more are at the limit of
  exploitation

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POPULATION AND AVAILABILITY OFRENEWABLE RESOURCES

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Models of population growth
Logistic Population growth Nt
K/(1K-N0/N0e-rt)
tgeneration rintrinsic increase rate Nt
population size at time t. Kcarrying capacity
N0initial population size eexponential
N
K
t
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Human Population Growth Was Thomas Malthus
correct?

• Practice problems
• At the beginning of 2000, the human population
  had reached a size of 6,000,000,000. Assuming
  that r0.001 (the intrinsic rate of growth of
  Lithuania) and an exponential growth model, what
  will the size of the human population be in 2025?
  
• Now, assuming the same information in A, but
  with r0.018 (the intrinsic rate of growth of
  Rwanda), use the exponential growth model to
  estimate the size of the human population in
  2025?
• Using the information in Problem A, plus a
  hypothetical carrying capacity, K10,000,000,000
  for the earth, estimate the size of the human
  population in 2025, using the logistic growth
  model?
• Repeat C, except assume that r0.018.

Press
Press
Press
Press
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r 0.001 (as in Latvia)
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r0.001 and r0.013
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Rising Death Rates

• In 1999 the Worldwatch Inst. reported that rising
  death rates are slowing world population growth
  for the first time since famine killed 30 million
  people in China in 1959-61.  Partly because of
  these rising death rates, the U.N. revised its
  estimate for world population in 2025 from 9.4 to
  8.9 billion.  Three factors are pushing the death
  rates up, especially in sub-Saharan Africa and
  the Indian sub-continent
• the HIV epidemic - between a fifth and a quarter
  of adults are already infected in Zimbabwe,
  Botswana, Namibia, Zambia and Swaziland. In
  India, four million adults are now HIV positive,
  more than in any other country.
• the depletion of aquifers - another serious
  problem in India, where water tables are falling
  annually by 1- 3 meters over much of the country.
• shrinking cropland area per person. More than
  half of the children in India are already
  malnourished and underweight.  Dwindling cropland
  also threatens food security in Nigeria, Ethiopia
  and Pakistan.