1. Interactions in Ecosystems
SNC 1DI

2. Ecosystem Interactions
Organisms in a community interact with one another in three main ways:
Competition
Predation
Symbiosis

3. Competition
Competition is an interaction between two or more organisms competing for the same resource in a habitat
competition can occur between members of the same species
eg. Mountain goats competing for mates
Competition can also occur between different species
eg. Both raccoons and ravens feeds on eggs from the same nest of a loon

4. Predation
Predation occurs when one organism eats another to obtain food
Prey animals are well adapted to avoid predation, for example:
deer can outrun bears
Porcupines have quills for protection
A stick insect camouflages itself

5. Predation

6. Symbiosis
Symbiosis is a close interaction between different species in which members of one species live in, on or nearby members of another species
There are three types:
Mutualism – benefits both species
Commensalism – benefits one species, the other is unaffected
Parasitism – benefits one species, the other is harmed

7. Mutualism

8. Commensalism

9. Parasitism

10. Characteristics of Populations
As populations grow, each individual gets a smaller share of the resources available in that area
Eventually, the number of births and deaths in a population will become equal, this is called equilibrium

11. Carrying Capacity
The carrying capacity is the maximum number of individuals that an ecosystem can support

12. Factors Affecting Populations
Various combinations of abiotic and biotic factors cause populations to increase or decrease
without any limits, 10 pairs of rabbits could expand to 10 million in just 3 years!
A limiting factor is an environmental factor that prevents an increase in the number of organisms in a population

13. A Population of Hares and Lynx

14. Limiting Factors Abiotic factors include: Biotic factors include:
Sunlight, water, soil, air, weather, natural disasters and human disturbances
Biotic factors include:
Competition among organisms, predators and disease-causing organisms