Environmental Biology

The conditions of life include everything that affects an organism during its
lifetime, the circumstances of biological existence, or the environments effects
upon an organism. The effect may be subtle; it may be severe. No environment
is permanent; change is inevitable. Habitat destruction eliminates
environments. The loss of habitat is the loss of the (necessary) conditions of
(existence for) life; the loss of habitat is the primary cause of extinction.
Habitat destruction occurs throughout time, in varying degrees of severity.
The degree in severity of extinction seems to parallel the degree of habitat
destruction.