sexta-feira, 6 de dezembro de 2013
Third generation BIOGEOGRAPHY
In the first attempts to explain the distribution of organisms across the planet, they not take into account the existence of continental drift, and as an explanation, an evolutionary center was established in Eurasia, from where departed all life forms. From this center there were successive dispersions to America, Africa and Oceania.
With the consolidation of the concept of Wegner's Continental Drift, new proposals emerge as the vicariance of "gondwanics" biotas and ideas as Antarctica bridge served dispersal to marsupials and southern temperate forests.
Third generation Biogeography is based on the idea of a planet growing, on which Pangea is synonymous with the Earth's surface, without a super-ocean, like the mythical Panthalassa.
We will begin from a smaller fully connected planet, where current oceans did not exist.
The waters covered almost the entire planet and few regions emerged from this great primordial ocean full of life.
According the data collected in the present oceans, we can say that the oldest sediments are in the Mediterranean region. For about 280 million years the planet has expanded and we had the beginning of a series of changes that resulted in a gradual opening and expansion of the oceans. With the opening of the Tethys Sea, more lands were exposed lower regions began to concentrating the waters forming the current oceans. Around 160 million years ago (Jurassic Period) the great oceans start to appear, this time opened up a large space in the North Pacific and lower portions around Africa, the current continents begin to isolate. Regional fauna begin to evolve independently of each other. Starting from a common substrate developed differently under different environmental conditions.
In the picture above I introduce an extremely didactic ordination, which will allow a better understanding as well as functioning as a mechanism for memory. Just as a "Biogeography Periodic Table". Starting from the lower left to the upper right corner we see a large diagonal. It is ordered the different stages of mammalian evolution and faunas that succeeded in time. We use the evolution of mammals as a base, since it reflects the surrounding environment.
See details in this link:
http://www.flickr.com/photos/nelson_gomes/11064218393/in/photostream/
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