population ecology

Topics: Population, Population ecology, Demography Pages: 21 (2211 words) Published: February 17, 2014
:

13.0 POPULATION ECOLOGY
(2 HOURS)

Learning outcomes :
13.1 Population Growth
(a) Explain biotic potential (r) and
environmental resistance and their
effect on population growth
(b) Explain carrying capacity and its
importance
(c) Describe natality and mortality and
their effects on the rate of population
growth

Learning outcomes :
13.1 Population Growth
(d) Explain population growth curves
(state the basic forms of growth
curves)
i. Exponential growth curve (human)
ii. Logistic growth curve (Paramecium sp.)
(e) Explain the limiting factors affecting
the population size :
i. Density dependent factors
ii. Density independent factors

Population Ecology
• The study of variables
• That determine the population density
and distributions
• Of a population in time and space

Learning Outcomes :
13.1 (a): Explain biotic potential (r) and environmental resistance and their effects on population growth

Biotic Potential (r) :

The number of offspring of an
individual organism that would survive
to reproductive age under ideal
condition

Learning Outcomes :
13.1 (a): Explain biotic potential (r) and environmental resistance and their effects on population growth

FIGURE 1

Learning Outcomes :
13.1 (a): Explain biotic potential (r) and environmental resistance and their effects on population growth

Biotic Potential is influenced by :

1. The age beginning of reproduction
2. How often reproduction occurs
3. How many offspring are born at a time

Learning Outcomes :
13.1 (a): Explain biotic potential (r) and environmental resistance and their effects on population growth

Biotic Potential & its Effect on Population
Growth
• Biotic potential (r) also varies according to the age
structure of a population
• It also may influence by male : female ratios
• When conditions are optimal and there are no
limitations, a population can grow at its maximum
biotic potential (the vital index, rmax)
• However, under natural conditions, the growth rate
of a population is never at the highest possible rate
because there is environmental resistance

•Learning Outcomes : :
Learning Outcomes
23.1 c: Explain environmental resistanceenvironmental resistance and their effects on population growth 13.1 (a): Explain biotic potential (r) and and discuss its effects on population growth

Environmental
Resistance :
The sum total of the factors that
prevent populations from continually
growing and therefore tend to keep
populations at constant levels

Learning Outcomes :
13.1 (a): Explain biotic potential (r) and environmental resistance and their effects on population growth

FIGURE 2

Learning Outcomes :
13.1 (a): Explain biotic potential (r) and environmental resistance and their effects on population growth

FIGURE 3

Learning Outcomes :
13.1 (a): Explain biotic potential (r) and environmental resistance and their effects on population growth

Environmental Resistance & its Effect on
Population Growth
• If there is zero environmental resistance, the
ability to continue to survive rises and a
population then achieves its full biotic potential
• If the condition continues, individuals in a
population
will
continue
to
increase
exponentially, resulting in overcrowding
• Accumulation of toxic waste, stress, disease due
to overcrowding & poor nutrition

Learning Outcomes :
13.1 (a): Explain biotic potential (r) and environmental resistance and their effects on population growth

• This is prevented by environmental resistance to
maintain the total number of individuals in the
population
• This ensures that the rate of increase (natality
rate) is the same as the rate of decrease
(mortality rate)
• Example : an overcrowded population in a
habitat will reduce food supply or attract more
predators
• When the population size drops to a level below
the carrying capacity, the effect of environmental
resistance is cancelled...
Continue Reading

Please join StudyMode to read the full document

You May Also Find These Documents Helpful

  • Ecology Essay
  • Ecology calculations Essay
  • Essay on Population Growth and Competition in Lemna sp. and Spirodela sp.
  • species area curves in Kawang's Reserve Forest, Sabah Malaysia Essay
  • Uganda's Population Essay
  • Population Control Essay
  • Population Ecology Essay
  • Population Pyramids Essay

Become a StudyMode Member

Sign Up - It's Free