1. Ecosystem Interactions
Environmental Science

2. What Shapes Ecosystems
Abiotic and Biotic Factors
Habitat – physical location where an organism lives
Niche – the use of the habitat by an organism (includes food, physical location, how it interacts with other organisms, etc.)

3. Species Interactions

4. Ways in Which Species Interact
These categories are based on whether each species causes benefit or harm to the other species.
Other types of interactions are possible.
Many interactions between species are indirect, some interactions do not fit in a category clearly, and other types seem possible but are rarely found. Therefore, many interactions are neither categorized nor well studied.

5. Competition
Competition – when different individuals or populations attempt to use the same resource
Within a species – food, mates, territory
Between species – food, water
Competition can occur even if the individuals never meet.
Flowers competing for the same pollinators

6. Community Interactions - Competition
When members of different species compete for the same resources, we say that their niches overlap.
These species will divide up the resources either by time or space – called niche restriction
Ex. Warblers in coniferous trees will live only on certain levels of the trees
Ex. Diurnal v. Nocturnal insects - both need the same resources, but some are only active in the day and others at night

7. Community Interactions - Predation
Predator/Prey Relationship
Predator – organism that hunts/kills
Prey – organism that is food (e.g. cat and mouse)
Sometime one predator may also be another organism’s prey

8. Specialists v. Generalists
Species that eat mostly one type of prey are called specialists
Ex. Canadian Lynx and the Snowshoe Hare
Generalists will eat whatever is easiest to find and capture
Ex. Coyotes or Wolves

9. Symbiosis and Coevolution
Symbiosis – two species who live closely together
Overtime, species in close relationships may coevolve. These species may evolve adaptations that reduce the harm or improve the benefit of the relationship.

10. Mutualism
Mutualism – symbiosis in which both organisms benefit – often each species depends on the other
Ex. Flowers and their pollinators

11. Ex. Barnacles on a whale’s skin or
Commensalism
Commensalism – symbiosis in which one organism benefits and the other is neither helped nor harmed.
Even seemingly harmless activity, however, might have an effect on another species.
Ex. Barnacles on a whale’s skin or
Birds nesting in trees

12. Parasitism
Parasitism – symbiosis in which one organism is helped and one is harmed
Parasite – the organism that feeds on another organism
Host – the organism parasite takes its nourishment from
Ex. Fleas and ticks
The difference between a
parasite and a predator is
that a parasite does not
usually kill its host.