A dominant species that constitutes a large proportion of the biomass and which affects many other species

A species which makes up only a small proportion of the total biomass of a community, yet has a huge impact on the community's organization and survival

A common species that has plenty of biomass, yet has a fairly low impact on the community's organization

A rare species that has minimal impact on the biomass and on other species in the community

High fertility, low or rapidly falling mortality rate, rapid population growth and a very young age distribution

High mortality high density, uneven population growth and a very old age distribution

High fertility, high density, rapidly rising mortality rate and very young age distribution

High infant mortality, low fertility, uneven population growth and a very young age distribution

Ectoparasitism

Decomposers

Endoparasitism

Symbiotic relationship

Competitive exclusion principal

Weiseman's theory

Allen's law

Gause's hypothesis