Chapter 5: Interactions

Predation

A species interaction in which one species kills and eats another

Competition

A species interaction in which two or more individuals, from the same or different species, compete for the same resource in the same area

Symbiosis

A relationship between individuals of two or more species in which at least one organism benefits from the interaction

Parasitism

One species benefits at the expense of the other (+/-)

Parasite

An organism that causes long-term disease while leaving the host alive, such as protozoa and worms

Host

An organism that is infected with a pathogen or parasite

Mutualism

Both species benefit from the interaction (+/+)

Commensalism

One species benefits and the other neither benefits nor is harmed (+/0)

Keystone species

A plant or an animal that plays a unique and crucial role in the way an ecosystem functions

Ecological niche

The role and space that an organism fills in an ecosystem, including all its interactions with the biotic and abiotic factors of its environment

Fundamental niche

The widest potential niche that a species could occupy without competitors, predators or parasites

Realised niche

The actual niche that a species occupies, given the restrictions placed on it by interactions with other species

Competitive exclusion principle

A key ecological principle that states that no two species can occupy exactly the same niche in an ecosystem

Resource partitioning

The creative use of space and time that reduces competition between species and allows many unique ecological niches to exist in the same area

Overexploitation

The unsustainable use of natural resources through hunting, logging, fishing and the gathering of plants, removing these organisms faster than they can be replaced

Habitat fragmentation

The process by which areas of a habitat are lost, resulting in a large continuous habitat being broken up into smaller, more isolated habitats

Monoculture

The agricultural practice of growing a single crop or species over a wide area for many consecutive years

Waterlogging

What happens to plants when the water table rises into the root zone; results in anaerobic conditions that may kill some plants; may also increase salinity levels in the soil

Salination

Increased salt concentration

Pollution

The introduction of harmful materials into the environment