1. Ecosystems
Part 2

2. Biotic Interactions in populations
Symbolic relationships (or symbiosis): is the interaction between different species that populate the same ecosystem.
There are three main interactions: Commensalism, mutualism and parasitism

3. Commensalism
Commensalism is a relationship where one species benefits while the other remains unaffected (not helped or harmed).
Typically one species will provide some sort of protection or transport for the other species.
Spanish Moss (old mans beard) anchors high up in trees to absorb sunlight

4. Mutualism
Mutualism is a relationship between two species where both benefit
The two species are unable to survive without each other.
Ants and Acacia trees:

5. Parasitism
Parasitism is a relationship where one species benefits while the other is harmed
Parasites are typically much smaller than their hosts, but come in greater numbers.
The parasite typically doesn’t kill the host, instead it causes damage.
For example: there are over 100 species of worm that can act as parasites in the human body

6. Niches: the special roles an organism has in an ecosystem. i. e
Niches: the special roles an organism has in an ecosystem. i.e. its all the physical, chemical and biological interactions required for a species to survive, grow and reproduce.
Competition: a harmful interaction between two species competing for the same resource . This is typically something like food, and will occur at the same area and time.
Predation: is a term used to describe the predator-prey interaction. The predator will hunt the prey for food. Predators will typically have adaptations to help them hunt prey (i.e. long teeth, claws, strong sense of smell)

7. Predation
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Number of hares per km2
Number of lynx per 100 km2
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Years

8. Biodiversity
Biodiversity refers to the variety and number of different individuals and species in an ecosystem.
Healthy ecosystems generally have high biodiversity.
Most biodiversity losses occur from the loss of habitat.
Humans often have a negative impact on biodiversity.
Many efforts are now made to lessen this impact in order to maintain biodiversity.