Interactions in Ecosystems SNC 1DI

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

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

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

Predation

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

Mutualism

Commensalism

Parasitism

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

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

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

A Population of Hares and Lynx

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