Download Science Notes: September 8, 2011 COMPETITON Competition may

Science Notes: September 8, 2011
COMPETITON
Competition may occur for many reasons. Usually this has to do with resources like food and
water, but also for other reasons like living space.
Competition occurs when two or more organisms compete for the same resources.
Example:
in
The Gila woodpecker makes nesting holes
the saguaro cactus. Because there are more
organisms than holes they must compete
with each other for the shelter these holes
provide.
Competition limits population size. When resources are scarce some individuals in a
population might not survive to raise any young.
In nature the most intense competition is between species.
It's because they usually need the same kinds of food and shelter...
Competition occurs WITHIN species and BETWEEN species...
PLEASE ANSWER THE FOLLOWING QUESTION NOW IN YOUR NOTES: What point
am I trying to make above? (what is the difference?)
...For example after the woodpecker (above) abandons its nest, the holes may be inhabited by
snakes, owls or lizards, for example.
LIMITING FACTORS:
In any ecosystem the availability of food, water, living space, mates, places to live and other
resources are limited.
A limiting factor is anything that restricts the number of individuals in a population.
Limiting factors include living and non-living features of the ecosystem.
The same limiting factor can affect more than one population in an area.
For example, a lack of rain can limit plant growth. As a result there would be fewer seed
produced than if there was normal rainfall. For mice that eat seeds the reduction in their food
supply could be a limiting factor. A smaller mouse population could then be a limiting factor
for hawks, owls or snakes that feed on mice.
CARRYING CAPACITY:
(1) Carrying capacity is the largest number of individuals (2) in one species (3) that an
ecosystem can support (4) over time.
Like a credit card...
…you might be able to go over the limit for a short time, but there are consequences.
Examples: (T-Chart)
If the population exceeds the environment's carrying capacity some individuals may not have
enough resources. As a result, they could die or be forced to move.
QUESTIONS?
I have two for you:
1. How are limiting factors related to carrying capacity?
2. Why are food and water the limiting factors that usually have the greatest effect on
population size?