Noun
keystone species (plural keystone species)
(ecology) A species that exerts a large, stabilizing influence throughout an ecological community, despite its relatively small numerical abundance.
Keystone species have lower levels of biomass in the trophic pyramid relative to the importance of their role. Source: Internet
Keystone species or public health threat? Source: Internet
Keystone species tend to have an effect on ecosystem function that is disproportionate to their abundance in an ecosystem. Source: Internet