Holarctic realm

The Holarctic realm is a biogeographic zone comprising the majority of habitats found across the continents of the Northern Hemisphere, uniting the Nearctic region of North America with the Palearctic region of North Africa and Eurasia, excluding Southeast Asia, the Indian subcontinent, and the southern Arabian Peninsula. These two regions correspond to the floristic Boreal Kingdom and are further subdivided into a variety of ecoregions. The Holarctic's unity comes from a shared glacial history: repeated Pleistocene ice ages shaped the landscape and species distributions, and as the glaciers retreated, plants and animals recolonized the newly exposed land from surviving refugia. The Bering land bridge allowed further movement between continents, so that the Palearctic and Nearctic share many species in common, a cross-continental connectivity that remains a defining feature of the realm. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/