Q. Define biogeographic realm?

Biogeographic regions are large areas that contain characteristic assemblages of animals and plants, d elineated on account of natural barriers such as oceans, mountains and deserts. A biogeographic region is generally characterised by high levels of species endemism.

Boundaries between biogeographic regions are called "biogeographic lines".

Examples are:

· Wallace's line between Southeast Asia and Australia (between Sundaland and Wallaceae), and
· Kangar-Pattini line between India and Myanmar.

The marine environment is three-dimensional with a distinct vertical zonation, each having its distinct associated species. Accordingly in a particular oceanic region, intertidal areas, the upper layers of the open ocean and the deep sea have very different assemblage by species.