Scope of Ecology

1
Scope of Ecology

• Ecology- Economy of Nature
• The study of the interactions of organisms with
• other organisms, and
• The physical environment or Habitat

2
Density and Distribution of Populations

• Population Density - Number of individuals per
  unit area or volume
• Population Distribution - Pattern of dispersal of
  individuals within a space of interest
• Limiting factors are factors that predominantly
  determine whether a species lives in a habitat

3
Population Growth

• Exponential Growth
• Rate of increase increases as the total number of
  females increases
• Biotic Potential
• Maximum population growth that can possibly occur
  under ideal circumstances
• Biotic potential is having full effect and
  birthrate is a maximum during exponential growth

4
Human Population Growth

• Human population has an exponential growth
  pattern
• Doubling time currently estimated at 53 years
• Population Size
• 1800 1 Billion
• 1930 2 Billion
• 1960 3 Billion
• 2000 6 Billion

5
Mortality Patterns

• A cohort
• Composed of all the members of a population born
  at the same time
• Survivorship
• The probability that newborn individuals of a
  cohort will survive to a particular age

6
Regulation of Population Size

• Density-dependent Factors
• Number of organisms present influences the effect
  of the factor
• Competition or Predation
• Density-independent Factors
• Number of organisms present does not influence
  the effect of the factor
• Natural disasters

7
Carrying Capacity

• Carrying Capacity
• The maximum number of individuals of a species
  the environment can continuously support
• The closer the population to the carrying
  capacity, the greater the environmental resistance

8
Life History Patterns

• r - Strategists (Opportunistic)
• Produce large numbers of offspring
• Small body size
• Early maturity
• No parental care
• Good dispersers and colonizers

9
Life History Patterns

• k - Strategists (Equilibrium)
• Produce small numbers of offspring
• Large body size
• Late maturity
• Significant parental care
• Specialists

10
Environmental Impact

• Environmental impact of a population is measured
  in terms of
• Population size
• Resource consumption per capita
• Resultant pollution

11
Greenhouse Effect

• Greenhouse gases
• Carbon dioxide, nitrous oxide, methane
• Allow sunlight to pass through atmosphere
• Reflect infrared back to earth
• Trap heat in atmosphere
• If Earths temperature rises
• More water will evaporate
• More clouds will form

12
Nitrogen and Air Pollution

• Acid Deposition
• Nitrogen oxides and sulfur dioxide are converted
  to acids when they combine with water vapor
• Acid rain dramatically reduces pH of surface
  waters in some areas
• Causes heavy metals to leach out of rocks,
  poisoning aquatic organisms and kill wildlife.
• Smog

13
Phosphorus

• Phosphorus does not enter the atmosphere
• Sedimentary cycle
• Phosphate taken up by producers incorporated into
  a variety of organic molecules
• Can lead to water eutrophication
• Biomagnification

14

• Sources of Pollution?