The realms delineate large areas of Earth's surface within which organisms have evolved in relative isolation over long periods of time, separated by geographic features, such as
oceans, broad
deserts, or high
mountain ranges, that constitute
natural barriers to migration. As such, biogeographic realm designations are used to indicate general groupings of organisms based on their shared biogeography. Biogeographic realms correspond to the
floristic kingdoms of
botany or
zoogeographic region of
zoology. From 1872,
Alfred Russel Wallace developed a system of zoogeographic regions, extending the
ornithologist Philip Sclater's system of six regions. Biogeographic realms are characterized by the evolutionary history of the organisms they contain. They are distinct from
biomes, also known as major habitat types, which are divisions of the Earth's surface based on
life form, or the adaptation of animals, fungi, micro-organisms and plants to climatic,
soil, and other conditions. Biomes are characterized by similar
climax vegetation. Each realm may include a number of different biomes. A
tropical moist broadleaf forest in Central America, for example, may be similar to one in New Guinea in its vegetation type and structure, climate, soils, etc., but these forests are inhabited by animals, fungi, micro-organisms and plants with very different evolutionary histories. The distribution of organisms among the world's biogeographic realms has been influenced by the distribution of
landmasses, as shaped by
plate tectonics over the
geological history of Earth. ==Concept history==