Ecosystem Interactions

Environmental Science

What Shapes Ecosystems AbioticAbiotic and BioticBiotic

Factors HabitatHabitat – physical

location where an organism lives

NicheNiche – the use of the habitat by an organism (includes food, physical location, how it interacts with other organisms, etc.)

Species Interactions

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.

Competition CompetitionCompetition – 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

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

Community Interactions - Predation

Predator/Prey Relationship PredatorPredator – organism

that hunts/kills PreyPrey – organism that is

food (e.g. cat and mouse)

Sometime one predator may also be another organism’s prey

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

Symbiosis and Coevolution SymbiosisSymbiosis – two species who live closely

together

Overtime, species in close relationships may coevolvecoevolve. These species may evolve adaptations that reduce the harm or improve the benefit of the relationship.

Mutualism MutualismMutualism – symbiosis

in which both organisms benefit – often each species depends on the other

Ex. Flowers and their pollinators

Commensalism CommensalismCommensalism –

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 orBirds nesting in trees

Parasitism ParasitismParasitism – symbiosis

in which one organism is helped and one is harmed

ParasiteParasite – the organism that feeds on another organism

Host Host – the organism parasite takes its nourishment fromEx. Fleas and ticks

The difference between a parasite and a predator is that a parasite does not usually kill its host.