They often contain the limits of distribution of the biota of neighbouring regions.
[1] Biotones are especially useful in marine biogeography, where the movement of water may result in substantial overlap in the floral and faunal components of adjacent regions.
This region is a biotone characterized by the transition between tropical and temperate waters.
Tropical biota that do not extend into temperate areas would be at the limit of their range in this biotone, and vice versa.
The co-occurrence of biota that are normally distinct can result in unusual ecological relationships.