Populations and Community

• Population:

  A group of interbreeding individuals of the same species

  May be closed or open (no migration or migration possible)
• Density-independent and dependent mortality:

  If limiting factors act increasingly as the populations rise, they are what? Density dependent (e.g. disease, competition, predation)

  If limiting factors act independently of the population size, they are what?

  Density independent (e.g. fire, flood, drought)
• Community:

  Assemblages of populations of different species interacting with each other.

  Each species has a niche (its role in using living and non-living resources).

  What niches are these?

  Where a species can survive and reproduce? Fundamental niche

  Where a species is restricted by interactions with others? Realised niche
• Biotic Interactions in Communities:

  Neither species is affected by the other? Neutralism

  One benefits from the interaction, no effect on the other? Commensalism

  One is at a disadvantage, the other unaffected? Amensalism

  Both benefit? Mutualism

  One benefits, one at a disadvantage? Predation

  Both disadvantaged by interaction? Competition
• Competition:

  Between species? Interspecific

  Within species? Intraspecific

  2 species dispute access to a resource directly? Interference

  2 species access a resource but do not come into contact directly. More efficient benefits to the detriment of the other species? Exploitative