Nearctic
The Nearctic is one of the eight major biogeographical regions of the world .
It includes almost all of North America , Greenland and the highlands of Mexico . In contrast, southern Mexico, southern Florida , Central America and the Caribbean islands together with South America belong to the Neotropic .
North and South America, which are now connected at the Isthmus of Panama , were separated about 180 million years ago and so developed very different species of plants and animals . When the supercontinent Pangea broke up , North America remained connected to Eurasia and thus became part of the newly formed northern supercontinent Laurasia , while South America became part of the southern supercontinent Gondwana . With the opening of the Atlantic Ocean , North America and Europe separated .
North America was later connected to Asia ( Beringia ) and South America ( Isthmus of Panama ) by land bridges . This allowed an exchange of species between the continents , the so-called Great American exchange ( Great American Interchange ).
As a result, the Nearctic and the Palearctic share a large number of animal and plant species. The two biogeographical regions are therefore also linked to form a common Holarctic region.
Many large animals, e.g. B. Horses , camels , mammoths , mastodons , early bison , saber-toothed tigers and short-faced bears died out at the end of the last Ice Age in the course of the Quaternary extinction wave with the simultaneous settlement by humans . Scientists believe that it was not the change in climate but the extinction caused by human hunting and the resulting scarcity of food for predators that caused the extinction of species.
In addition to humans, the modern American bison , grizzly bear and wapiti were able to gain a foothold through the ecological niches that became free.
Originally the dogs (Canidae), the camels (Camelidae) and the horses (Equidae) only occurred in the Nearctic. The Paarhuferfamilie the Gabelhorn carrier (Antilocapridae) always remained limited to this region.
The cheetah originally developed in North America and first came to Asia and later to Europe and is still mainly found in Africa today. The short-faced bears also only lived in North America. The only surviving species in this family is the spectacled bear that still lives in South America today .
literature
- Dieter Heinrich, Manfred Hergt, Rudolf Fahnert: dtv-Atlas Earth . Physical geography. 1st edition. Deutscher Taschenbuch Verlag, Munich 2006, ISBN 3-423-03329-0 , pp. 266-267 .
