commensalism A type of symbiosis in which one species benefits while the other is not
affected.
community An assemblage within the same area, of populations of different species inter-
acting with one another.
competition Organisms of the same or different species compete for a limited supply of
at least one resource, thereby lowering the fitness of one organism by the presence of
the other.
competitive exclusion principle Species less suited to compete for resources will either
adapt, be excluded from the area, or die out.
grazing A type of predation where the predator eats part of the prey, but rarely kills it.
keystone species A predator species that plays an important role in the community by
controlling the prey population and, thus, the populations of other species in the
community as well.
mutualism A type of symbiosis in which both species benefit.
parasitism Atypeofsymbiosisinwhichtheparasitespeciesbenefits, whilethehostspecies
is harmed.
predation An interaction where a predator organism feeds on another living organism or
organisms, known as prey.
symbiosis Close and often long-term interactions between different species, in which at
least one species benefits.
true predation A type of predation where the predator kills and eats the prey.
Points to Consider
- How do you think predation helps a species to survive?