Env. Science: Species Interactions
The zebra mussel has completely dispaced 20 native mussel species in Lake St. Claire.
The Niche: describes an organism’s use of resources and functional role in a community.
Includes not only where an organism lives, but also includes:
what it eats
how and when it responds
what other organisms it interacts with
It is affected by an organism’s tolerance — its ability to survive and reproduce under changing environmental conditions.
Some organisms have very restricted tolerance ranges and are called SPECIALISTS
Some organisms have a very wide tolerance range and are called GENERALISTS
The full niche of a species is called its fundamental niche; a niche restricted by competition is called a realized niche.
Organisms compete when they seek the same limited resources.
In rare cases, one species can entirely exclude another from using resources — this is called competitive exclusion.
To reduce competition, species often partition resources, which can lead to character displacement.
Character displacement is the evolution of physical characteristics among the competing species.
Predation is the process by which a predator hunts, kills, and consumes prey.
Causes cycles in predatory and prey population sizes.
Defensive traits such as camouflage, mimicry, and warning coloration have evolved in response to predator-prey interactions.
Some predator-prey relationships are examples of coevolution, the process by which two species evolve in response to changes in each other.
Parasitism: one organism (the parasite) relies on another (the host) for nourishment or some other benefit.
Symbiosis: the definition is disputed, but for now, we will say that it is a long-lasting and physically close relationship in which at least one organism benefits.
Herbivory: an animal feeding on a plant
Mutualism: a relationship in which two or more species benefits
Commensalism: a relationship in which one species benefits while the other is unaffected.