Download population - Hicksville Public Schools

Aim: How are populations limited by the
carrying capacity of the environment?
Relationships in an Ecosystem
Predator vs. Prey
The stability of an Ecosystem
is dependent on the balance of
these relationships/cycles.
Photosynthesis
Water Cycle
3 Factors that can affect Population Size:
* Number of births
* Number
entering or
leaving the
population.
* Number of Deaths
What limits the size of the student
population?
Ex: The number of desks, teachers, space…
Limiting Factors
• Limiting Factors- anything that limits or
decrease the size of a population
• Abiotic
Biotic
What abiotic factors that may limit the
size of a population?
•
•
•
•
•
Sunlight/Energy
Temperature
Water
carbon dioxide
Oxygen
•
•
•
•
•
Soil
minerals
pH
Nutrients
wind
These resources are finite (limited) not infinite (unlimited).
Finite- bounded or limited in magnitude (limited).
Infinite- having no limits or boundaries (unlimited).
What limiting factors can affect the
size of a population?
•
•
•
•
•
Competition*
Predation*
Parasitism & disease*
Drought (Climate Extremes)
Human Disturbances
Competition
The struggle for resources among organisms within
a species or population or between members of
different species.
How does competition limit populations?
The population that is the best adapted to the
environment will increase and the other population
will die out or will migrate.
Predator vs. Prey
The relationship between both that
limits the growth of both populations.
How Does Predation limit populations?
Predation (Predator-prey relationship)
limit the
As predators eat their prey, they ____________
_________
growth of the prey.
If many prey are killed, predators begin to ______,
starve
population is reduced
& their _________________________.
*With fewer predators, the size of the prey
population begins to recover.
*What is going on in this graph?
*The graphs show that the relationships
are cyclical.
*The population of one depends on the
other.
Movie – Importance of having predators
http://www.bbc.co.uk/schools/gcsebitesize/biology/
livingthingsenvironment/0habitatsandpopsrev8.sht
ml
Carrying Capacity:
• The maximum number of
organisms that the
ecosystem can support.
• It is determined by the
limiting factors &
competition.
What happens to new, small populations?
The population usually will increase until the
carrying capacity is reached and then the
population will remain stable.
Can the carrying capacity of an environment change?
Yes, anytime there is a natural
catastrophe or when humans take
space away from the ecosystem
•Natural disaster
•Seasonal cycles
•Human activities