A keystone species is a species that has a disproportionately
strong effect on the health and functioning of its ecosystem.
Identifying and studying keystone species
can be useful in studying and preserving the health of an ecosystem
Here's two examples of keystone species.
Reintroducing wolves in the greater Yellowstone ecosystem
had cascading positive effects
on plant populations, on soil health,
in all the processes that depend on both.
And restoring sea otters along the Pacific Coast of North America
depressed populations of marine herbivores and predators,
which allowed other species to recover.
Keystone species are not just limited to charismatic mammals.
Effectively any organism in an ecosystem could be keystone.
The critical characteristic of a keystone species
is that a large portion of the flow of energy and sources through an ecosystem
depends on that species.
This can occur when the species consumes resources itself,
or promotes or inhibits the consumption of resources by others.
Consider the north american coastal redwood
Not only does this tree provide raw sources of carbon
for other organisms to consume
it also alters the local climate.
Increasing moisture, building organic rich soils
and providing a complex substrate
for other organisms to live in
from bryophytes to birds to insects to microorganisms.
In effect, redwoods create ecosystems within ecosystems
That's how highly connected they are within the network of
all biological interactions along the Pacific Coast
These species and many others were discovered by accident
by misguided human actions leading to their removal.
Resulting in negative downstream consequences due to their absence.
But it doesn't have to be that way.
Tools from Network Science now allow us to identify keystone species
using information about the interactions that connect members of an ecosystem.
Such as when on spices feeds on another or relies on another for its survival.
Using this network approach we don't have to wait for the accidents to realize
what drives the ecosystem health.
Understanding keystone species can help us explore ways
to restore biodiversity that sustains us.
And here, at the Santa Fe Institute we'd like to apply concepts
across disciplinary boundaries so we can use the idea of keystone species to
understand how innovations revolutionized economy or how life itself began on earth.