Amphiborealic Distribution of Organisms

Amphiborealic Distribution of Organisms

 

disconnected (severed) distribution of certain species, or more rarely of closely related genera, of animals encountered in the temperate zone (boreal waters) and the border of the arctic area of the Atlantic and Pacific oceans. These species are absent from the seas which wash northern Asia and northern North America and from tropical and warm seas.

The term “amphiborealic distribution of organisms” was proposed by L. S. Berg in 1934. Amphiborealic distribution is explained by the fact that the water temperature of the polar seas during the Pliocene epoch was significantly higher than it is today, and thus many species of sea animals were able to penetrate from the North Atlantic through the polar seas that wash the northern coast of Asia into the northern part of the Pacific Ocean and to move in the opposite direction. The significant cooling which came during the Recent Epoch caused a sharp drop in the temperature of the polar seas, which resulted in a number of species there becoming extinct. In the more southerly latitudes of the Atlantic Ocean, the Bering Sea, and the Pacific Ocean, the temperature drop was not so significant, and the aforementioned sea animals did not become extinct.

Amphiborealic distribution includes representatives of different groups: dolphins (Grampus griseus and Phocaena phocaena), common seals, auks, sharks (herring, giant, and Greenland), ocean herring, cod, and prawns (Pandalus borealis).

REFERENCE

Zenkevich, L. A. Biologiia morei SSSR. Moscow, 1963.