Habitat

• Species?are adapted, or well-suited, to life in a particular habitat
• A habitat can be defined as?the place where an organism lives
  • A habitat can be?large,?e.g. a desert, or?small,?e.g. an individual tree
    • Small habitats are sometimes referred to as?microhabitats
  • Some species are habitat?specialists,?meaning that they can only survive in a very specific type of habitat, while others are?generalists?and can survive in a range of habitats
    • Generalists are more likely to be able to invade and take over a new habitat; such species are known as invasive species
      • Humans sometime release new species into a habitat, either accidentally or on purpose; these species can disrupt the normal species interactions in a habitat and cause serious problems

Population

• When a species is found in a habitat, that habitat is said to support a?population
• A population can be defined as?all of the individuals of one species living in a habitat
  • The size of a population can be measured; this is the?abundance?of a species in a habitat
  • The exact location of a population within a habitat is a species'?distribution?within that habitat

Community

• Species?do not exist by themselves in their own isolated environment; they?interact?with?other species, forming?communities
• A community can be defined as?multiple populations living and interacting in the same area
  • For example, a garden pond?community?is made up of populations of fish, frogs, newts, pond snails, damselflies and dragonflies and their larvae, pondweed, water lilies, and all other populations living in the pond

Ecosystem

• Communities interact with the?non-living components?of the?habitat?they live in, forming?ecosystems
• An ecosystem can be defined as?a?community and its interactions with the non-living parts of its habitat
  • There is a?flow of energy?within an ecosystem and nutrients within it are recycled
  • There are both?biotic?and?abiotic?components?within an ecosystem
  • Ecosystems?vary greatly in size and scale
    • A small pond in a back garden and the open ocean could both be described as ecosystems
  • Ecosystems?vary in complexity
    • A desert is a relatively simple ecosystem
    • A tropical rainforest is a very complex ecosystem
  • No ecosystem is completely self-contained as organisms from one ecosystem can often move to another
    • E.g. birds and aquatic animals are able to migrate long distances to feed from multiple ecosystems

Individual members of a species together in a habitat form a population, populations interact within a community, and communities interact with each other and with non-living components of their habitat to form an ecosystem.