Download Population Dynamics

Population Dynamics
Organism Interactions as a Limiting
Factor.
Predation
• Predation is a limiting factor
• What is a limiting factor? How could predation
be a limiting factor?
• There is a cycle to predation. This cycle occurs
both in laboratory settings as well as in nature.
(how do you think the two would differ)
• Predation also helps keep prey numbers down so
that there is enough resources for the prey.
(usually takes the young, old, or injured members
leaving behind a stronger population)
• When the hare pop. increases, there is more food
for the lynx pop., thus the lynx pop also
increases.
• When the lynx pop. increases then predation
increase thus causing the hare pop. to decrease.
• With fewer hares, the lynx pop. drops and then
the hares can increase again thus continuing the
cycle.
• So the two sides affect each other.
Competition
• Competition is when organism of the same species
need the same resource and that resource is
currently scarce.
• Competition can also pit one species against
another if they have the same niche.
• Competition also follows a cycle.
– When numbers are down resources are abundant
allowing numbers to increase.
– When the numbers increase it becomes harder to find
necessary supplies like food and shelter.
– Numbers will then decrease. Once numbers are down,
the resources build back up and the cycle continues.
Stress and Crowding
• When a population gets crowed or has a high
population density, then stress occurs.
• Stress is characterized by:
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Aggression
Lack of parental care
Decreased fertility
Decreased resistance to disease
• Stress is a negative factor for populations and
even becomes a limiting factor to help keep pop.s
at or below the carrying capacity.