About Keystone Species

1. Herald
&
Wandaphira

3. Introduction
• A keystone species is a plant or an animal that
plays a unique and crucial role in the way an
ecosystem functions.
• Without keystone species, the ecosystem
would be dramatically different our cease to
exist altogether.

4. • In 1995, 14 wolves were reintroduced to the Yellowstone
National Park. The deer started to avoid some areas. The
deer’s absence in these areas meant that plant could grow
again and the trees began to flourish. With trees and
bushes came more berries and bugs which resulted in more
birds. The beaver previously extinct, returned. The wolves
also fed on the coyotes which led to the population growth
of mice and rabbit. This attracted red foxes, weasels,
badgers and hawks. Even the population of bald eagles
rose.
• With better balance of prey and predator, other species
thrived.
• This is a classic example of role played by keystone species.

5. History
• The theory that the balance of ecosystems can rely on
one keystone species was first established in 1969 by
an American zoology professor Robert T. Paine
• He coined the term "keystone species," he observed
the habitat of the Pisaster ochraceus sea star, Paine
experimented by actually changing the habitat. Paine
and his students from the University of Washington
spent 25 years removing the sea stars from a tidal area
on the coast of Tatoosh Island, Washington, in order to
see what happened when they were gone. He was one
of the first scientists in his field to experiment in nature
in this manner.

6. • A keystone species is often, but not always a
predator. A few predators can control the
distribution and population of large numbers of
prey species.
• Eg., A single mountain lion can roam hundreds of
kilometres. The deer, rabbits and bird species in
the ecosystem were affected by the mountain
lion including their feeding behaviour and where
they chose to nest or make burrows.

7. • Herbivores can also be keystone species
• Eg., In Serengeti plains in Tanzania, Elephants
are a keystone species. Elephants eats small
trees that grow on the savanna. Even if such
trees grew to a height, the elephants were to
knock over the tree and uproot them. This
feeding behaviour keeps the savanna from
tuning into a forest or a woodland

8. Conclusion
A keystone species’ disappearance
would start a domino affect, such
that if the species goes extinct all
the other species and the ecosystem
would fail.

9. • Without the keystone species, new plants or
animals could invade the habitat and push out
the native species.
• Eg., In the Sonoran Desert of North America,
some species of hummingbirds are the keystone
species such that they pollinate many varieties of
native cactus and other plants. In areas of the
desert with few humming birds, invasive species
have taken over the ecosystem.

10. Thank You

11. References
• www.nationalgeographic.org