∞ generated and posted on 2016.08.18 ∞
Otherwise unoccupied ecological niche.
The idea behind adaptive zone is that a species is provided with an opportunity to exploit a niche and to do so without competition from organisms that are much more well adapted to that niche. As a consequence, the invading organism need not be very adept at exploiting that niche but instead simply adept enough to survive. With time, however, surviving populations will have opportunity to indeed adapt to the niche, becoming better competitors within it.
Adaptive zones are represent evolutionary opportunities to organisms, that is, opportunities to modify how they go about doing things under circumstances in which the costs of such experimentation are lower. Substantial adaptation can occur under such circumstances both because the costs of "mistakes" are lower and the need for substantial ecological sophistication is low.
"In the land of the blind, the one-eyed [organism] is king." (Desiderius Erasmus)
With the loss of the dinosaurs, for example, the niche formerly occupied on land by large vertebrates – backbone-containing animals, that is, tetrapods – was vacant and so was available to be filled by surviving mammals.
With plants, or at least their green algae ancestors, the adaptive zone was dry land.