A species that has decreased until it is almost
endangered is considered

A species that no longer exists is considered

The term used to describe the wide variety of life on
Earth is

A species that may become extinct if its population
decreases further is considered

A condition that controls the size or growth of a
population is called a

When a community has stabilized and succession
has slowed down or stopped, it is a

The gradual replacement of one community by another
is called

The first species to establish themselves in a lifeless
area form a