1. Why do organisms compete?

2. Unit Standards
5.L.4B.1
Analyze and Interpret data to explain how organisms obtain their energy and classify organisms as producers, consumers (including herbivore, carnivore, and omnivore), or decomposers (such as Fungi, Bacteria insects and molds).
5.L.4B.2
Develop and use models of food chains and food webs to describe the flow of energy in an ecosystem.
5.L.4B.3
Construct explanations for how organisms interact with each other in an ecosystem (including predators and prey, and parasites and hosts).
5.L.4B.4
Construct scientific arguments to explain how limiting factors (including food, water, space, and shelter) or newly introduced organisms can affect an ecosystem.

3. Why do organisms compete?
Life in an ecosystem is a constant struggle. Food, water, space, and other resources are restricted. Organisms struggle to get their share of each resource.

4. Why do organisms compete?
Competition- the fight for limited resources.

5. Why do organisms compete?
Organisms within a population compete with one another. A fox must compete with other foxes to catch rabbits.

6. Why do organisms compete?
Populations also compete. Foxes and hawks both eat rabbits. Since there is a limited number of rabbits, the two predator populations compete for food.

7. Why do organisms compete?
The rabbits must also compete with other herbivore populations for their food.

8. Why do organisms compete?
Ultimately, the survival of populations comes down to resources.
Limiting factor- any resource that restricts the growth of populations.

9. Why do organisms compete?
A forest gets more rainfall and it much warmer in summer than winter.
In summer, the forest can support many more populations than in winter. In this case, rainfall and temperature are limiting factors.

10. Why do organisms compete?
Common abiotic limiting factors include water, temperature, weather, soil type, space to grow, shelter, and sunlight.
Light
Temperature
Weather
space

11. Why do organisms compete?
Biotic limiting factors can also limit ecosystems. A prairie ecosystem has more producers than a desert ecosystem.
As a result, the prairie can support more herbivores, which support more carnivores.
In this case, the amount of available food is the biotic limiting factor for the desert ecosystem.
With more available food, the prairie ecosystem can support more populations.

12. Why do organisms compete?
Together, biotic and abiotic factors determine the carrying capacity for each population.

13. Why do organisms compete?
Carrying capacity- is the greatest number of individuals with in a population that an ecosystem can support.

14. Why do organisms compete?
For example, a rain forest can support a certain number of jaguars.
If the jaguar population starts to rise, food becomes harder to find.
Soon, some of the jaguars die and the population returns to its former level.

15. Why do organisms compete?
Overcrowding also limits growth.
An algae population in a nutrient-rich pond may seem like it can grow indefinitely.
But the algae will eventually get so thick that they start to use up the oxygen in the pond.
Without enough oxygen for respiration, the algae and other organisms begin to die off.