A plant or animal that plays a unique and crucial role in the way an ecosystem functions.
What is a KEYSTONE SPECIES?
This is a diagram.

What is a CLADOGRAM?
The role and space that an organisms fills in an ecosystem, including all its interactions with the biotic and abiotic factors of its environment.
What is ECOLOGICAL NICHE?
a group of organisms that consists of a common ancestor and all its lineal descendants
What is a CLADE?
A subset of the fundamental niche where an organism can maintain a stable species population.
What is REALISED NICHE?
a system of taxonomy in which the organisms are classified into clades (groups) based on collective characteristics and having common ancestry
What is CLADISTICS?

In the example above which type of niche are all three birds living in separately?
What is REALISED NICHE?
Trait/s shared by a horse and wolf.

What is HAIR?
Usually defined as a state in which two species competing for the same resources cannot stably coexist if other ecological factors are constant. Also called Gause's principle.
What is COMPETITIVE EXCLUSION PRINCIPLE?
The three assumptions of cladistics.
What is COMMON ANCESTRY, BIFURCATION, and PHYSICAL CHANGE?