Edexcel A (SNAB) A Level Biology:复习笔记5.1.3 Niches: Distribution & Abundance

Niches: Distribution & Abundance

  • The place where a species lives is known as its habitat
  • Species will occupy a specific niche within a habitat
  • The term niche can be defined as the role of a species within its habitat
  • The role of a species includes
    • What it eats
    • Which other species depend on it for food
    • What time of day a species is active
    • Exactly where in a habitat a species lives
    • Exactly where in a habitat a species feeds
  • No two species can fill the same niche within a habitat; if this ever happens the two species will be in direct competition with each other for resources, and one of the two species will out-compete the other, causing it to die out in that particular habitat
    • It can sometimes seem as though species are occupying the same niche, but there will still be subtle differences in their role; e.g. they might feed at different times of day, or have different food sources
  • The niche filled by a species determines its abundance within a habitat
    • The term abundance can be defined as the number of individuals of a particular species living in a habitat
    • If two species occupy a similar niche within a habitat, they will be competing with each other, so their populations will be smaller, and their abundance will therefore be lower
  • The niche filled by a species determines its distribution
    • The term distribution can be defined as where a species lives
    • Species can only survive in habitats to which they are well adapted; if they are not well suited to a habitat's biotic and abiotic factors then they will move to a more suitable habitat and their distribution will change

Feeding location is an example of a feature that may differ between niches.