Dominant Species Vs. Keystone Species
Transcript Dominant Species Vs. Keystone Species
What is a Keystone Species?
• A Keystone Species =
Species that plays a critical role in
maintaining the structure of an
ecological community, and its impact
on the community is greater than
expected based on its relative
abundance or total biomass.
Keystone Species: Background
• Introduced by Robert Paine in 1969
• Observed that the carnivorous starfish
Pisaster ochracceus, played a key role in
maintaining the balance of all other species in
• Removing the starfish, species diversity
quickly dwindled and affected the
• Not abundant in a community
• They exert strong control on community
structure not by numerical might, but by
ecological roles, or niches.
• Niche-is a term describing the relational
position of a species or population in its
ecosystem to each other.
What is a Dominant Species?
• A Dominant Species =
Species that predominates in an
ecological community, particularly
when they are most numerous or
form the bulk of the biomass.
• It is based highly on those species in a
community that have the highest abundance
or highest biomass.
• They exert powerful control over the
occurrence and distribution of other species.
Why do some species become
dominant in a community?
• Species earn their dominance because they
are most competitive in exploiting limited
• Ex. American chestnut was a dominant tree
and species in North America
Elimination of Dominant
• When a dominant species is eliminated it
can sometimes drastically hurt a
community, where in some communities it
may not effect a species.
• If a community isn’t drastically affected it’s
because one or more species less
competitive may take over the dominant
• Keystone is thus a species that is not
numerically abundant but is necessary to
keep a population diverse and thriving.
• Whereas dominant species are large in size
in the various biomes and take on a big role
in the nourishment of a community
The End :)
<3 Tia and Matt