Palearctic realm

Definition

The largest of Earth's eight biogeographic realms, encompassing the temperate and cold regions of Europe, Asia north of the Himalayan foothills, and North Africa. It is bounded by the Nearctic realm across Beringia and the Atlantic, the Oriental realm to the southeast, and the Afrotropical realm to the southwest. The Palearctic shares many temperate-adapted insect and arachnid lineages with the Nearctic due to Pleistocene land connections and subsequent vicariance, yet retains distinctive endemic groups shaped by continental climate severity and Pleistocene refugia.

Etymology

From Greek palaios (ancient, old) + arktikos (northern, of the Bear), referring to the ancient northern lands of Eurasia.

Example

The Palearctic realm's steppe and taiga zones harbor characteristic ground beetle assemblages (Carabidae: Carabus, Calosoma) that differ markedly from Nearctic equivalents, with many species showing disjunct distributions reflecting post-glacial range shifts.

Synonyms

• Palearctic
• Palearctic ecozone

Related Terms

• biogeographic realm
• Nearctic realm
• Oriental realm
• Afrotropical realm
• Holarctic
• Pleistocene refugium
• vicariance
• disjunct distribution

Usage Notes

Often shortened to 'the Palearctic' in technical writing. Contrasts with 'Palearctic region,' an older term sometimes used more loosely for zoogeographic provinces. The realm's boundaries with the Oriental realm follow the Himalayan front and associated mountain systems; this transition zone (the Sino-Himalayan region) contains mixed faunas and is biogeographically complex. In entomological literature, 'western Palearctic' and 'eastern Palearctic' are frequently used informally to distinguish European-Mediterranean from Asian temperate faunas.