Land Bridge

Landbridges Defining a landbridge is a matter of understanding how land masses are formed and where they can be found. A landbridge is a tract of land that is sometimes submerged by the ocean, and sometimes it's not. As this is a fluid situation, the tract of land at times is large enough to accommodate migration between the two larger bodies of land between which it is located, and sometimes it is so small as to be non-existent.

The fluidity involved is based upon ocean waves and the depth of the ocean as it ebbs and flows. Because the ebbs and flows of the ocean change so slowly, the resulting landbridge usually changes just as slowly. There are a number of notable landbridges including the Beringia Straits that in centuries gone by connected North America and Asia. The Sinai Peninsula connected Asia and Europe, and the Isthmus of Panama connects North America and South America.

Description A landbridge can best be described as the exposed portions of the ocean bottom. A landbridge occurs because the ocean water that normally covers it has receded which leaves the land exposed that was not exposed before. A landbridge allows the migration of humans, plants and animals from one continent to another. As one recent study states "climatic and geological changes across time are presumed to have shaped the rich biodiversity of tropical regions" (Smith, Amei, Klicka, 2012, p. 3520).

It is speculated that this rich biodiversity is due to the fact that migration could (and can) takes place via the Isthmus of Panama. This holds true for the continents connected by other landbridges as well. Plants and animals found in one continent can easily be traced back to a connected continent and vice versa. The strongest premise can be said that the animals, plants and wildlife migrated between the two continents and in order for that to happen there had to be a connecting landbridge.

Another study determine that "results are in accordance with a recent leading edge mode of colonization, particularly towards the east throughout Canada/Greenland and across the North Atlantic into Scandinavia and Svalbard" (Bronken Eidesen, Carlsen, Molau, Brochmann, 2007, p. 1559). The same study concluded that C. tetragona expanded eastwards from Beringia several times and that the earlier emigrants of this woody species became extinct" (p. 1560). Size The size of a landbridge is a primary factor in whether migration takes place or not, and if that migration is long-term or short-term in aspect.

There are times when the size of the landbridge will allow for migration, and there are times when such migration is not only inconclusive because of the size of the landbridge but also due to the prevailing factors of the linebridge as well. The size can be quite large, and last for quite a while which is conducive to migration, or the landbridge size can be quite small or troubled and that is not conducive at all to migration. The Bronken et al.

study determined that migration of certain emigrants took place over a number of centuries interspersed by eras of no migration at all. It can be conjectured therefore that size is a prevailing factor and can be both positive and.