1. Introduction to Ecosystems
APES 1.1
Introduction to Ecosystems

2. The Niche
Describes an organisms use of resources and functional role in a community.
Includes:
Habitat
Food eaten
Reproduction (how and when)
Interactions with other organisms
Example: A large part of a spider’s niche is to prey on food that is caught in its web.

3. The Niche The Niche can be affected by an organism’s tolerance
It’s ability to survive and reproduce under changing environmental conditions.
Specialist: very restricted tolerance range
Ex: Giant Panda, Koala
Generalist: Wide tolerance range, can live in a wide variety of places with a wide variety of resources
Ex. Rat, mouse, cockroach

4. The Nice
Organisms with similar roles in the environment compete when they seek the same limited resources.
Competitive Exclusion can occur in rare cases when one species can entirely exclude another from using the resources.

5. The Niche
Fundamental Niche: When a species fulfills all its roles and uses all of the resources possible.
Realized Nice: Resources and roles fulfilled by a species competing with other species (adjusted)

7. Resource Partitioning: When species divide (partition) the resource they use in common by specializing in different ways.
Ex: One bird may eat in the morning while one eats at night. Or, types of food they eat from the same resource.
The Niche

9. Competition Species Interactions
When organisms of the same or different species attempt to use a limited resource in the same place at the same time.
Ex: Lions and hyenas compete for the same prey such as zebras
Ram Fight

10. Predation Species Interactions
One organism (the predator) captures and feeds on another organism (the prey)

11. Species Interaction
Predation can cause cycles in predatory and prey population sizes.
Why?

12. Species Interactions Predation & Evolution
Likewise, individuals predators that are better at hunting will likely be more successful than less skilled hunters so natural selection leads to evolution of characteristics that enable predators to be better hunters
Prey that are better at defending themselves will be more successful and pass these traits onto their offspring.

13. Symbiosis Species Interactions
A close relationship between two different species.
Parasitism
Mutualism
commensalism

14. Parasitism Species Interactions
One organism benefits at the expense of another
the other is harmed

15. Mutualism Species Interactions
Both organisms benefit from the relationship

16. Commensalism Species Interactions
One organism is benefiting and the other is neither harmed nor benefited