The Tropical barrier separates the Tamaulipan and Veracruzian biotic provinces.

Being euryphagous, crows exert a stabilizing influence on many kinds of prey and on the biotic community as a whole.

The major part of this biotic area lies within the Lower Sonoran Life-zone.

These birds are widely distributed and vary geographically without corresponding to the Biotic Provinces.

Biotic relations of the wood rat (Neotoma fuscipes) in the Berkeley Hills.

The three barriers separate the four Biotic Provinces in Tamaulipas.

In our literature survey we found records of biotic associations for about 400 species.

In classifying the biotic associates of cockroaches, we were immediately confronted with a problem in semantics.

The Californian Biotic Province dominates the biotic aspect of the coastal slope of the range.

Each of these has varying combinations of physical and biotic factors that are important in the ecology of amphibians.