J and S Curves
J and S Curves
• If things were perfect for a population and all the
individuals survived and reproduced at the
maximum rate, that growth rate is called the biotic
potential.
• It is certainly not common for a population to
grow at its biotic potential.
• When fish are introduced into a lake where there
is plenty of food and space and there are no
predators, the fish can reproduce at their biotic
potential, but not for a long time.
J and S Curves
• The graph of a
population growing at
its biotic potential,
which is called
exponential, can be
very steep.
• The graph of a
population that grows
exponentially is called
a J-shaped curve.
J and S Curves
Carrying Capacity of an Ecosystem
• The area occupied by a population can’t provide
unlimited resources such as food and water.
• These factors limit the population growth and
many times bring about death rates that equal the
birth rates.
• When this happens, the population size reaches a
stable balance.
J and S Curves
• The graph of a
population that grows
until it reaches a stable
size based on the
carrying capacity is
called an S-shaped
curve.
J and S Curves
• A.Begins with a slow rate
of growth.
• E. As the number of mates
increase, the growth rate
speeds up.
• C. When the population
reaches a certain level,
growth rate slows down
and population reaches a
steady state.
J and S Curves
• At this point, if
environmental
conditions remain
stable, population will
continue to exhibit
minor fluctuations.