10, Jun, 2017
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ZOO GEOGRAPHICAL EVIDENCES OF ORGANIC EVOLUTION

The study of the distribution of animals on the globe is called Zoo geography. The different kinds of animals living in a particular area forms the fauna. The geographical distribution of animals provides a good evidence for organic evolution.

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1. FAUNA OF AFRICA AND MADAGASCAR

The earth inhabits various kinds of animals. But all kinds of animals are not present in all regions of the earth. Hence the distribution is not uniform. It is mainly due to the difference in climatic conditions of various regions. But even though the climatic conditions are same in southern hemisphere, the fauna varies. For example the fauna of Africa belongs to Ethiopian region differs from the fauna of Madagascar even though both the regions are present in subtropics. The African fauna consists of Lions, Elephants, Rhinos, Chimpanzees and Gorilla. Where as Madagascar consists of primitive primates Lemurs. This can be explained that both the regions had the same fauna i.e lemurs during the early tertiary period. Due to the separation of Madagascar from main land by sea water, Lemurs were unable to migrate into new places to evolve into new individuals. Where as the African fauna migrated into new regions hence they evolved into new individuals.

2. FAUNA OF AUSTRALIA AND SOUTH AMERICA

The fauna of Australia differs from that of South America even though the climatic conditions are same. The fauna of South America located d in neotropical region consists of bears,llamas, sloths, armadillos etc. This is because Australia was separated from the main land, when the globe consisted of prototherians and metatherians. As these individuals are unable to migrate into new regions, they are confined to Australian region only. Where as these individuals in main land migrated into new climatic conditions, hence evolved into eutherian mammals. The South America was seperated from main land when the land consisted of armadillos, slothes etc.

zoo geography evolution
Figure 604.1: Fauna of Australia and South America

3. FAUNA OF POLES

The south and north poles consist of same ecological conditions. The south pole consists of penguins, where as the north pole consists of polar bears. This difference is mainly due to adaptability.

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4. DISCONTINUOUS DISTRIBUTION

Another peculiar fauna of distribution is that similar animals exist in widely separated regions. But in between these regions there are no such representatives. For example lung fishes are found in Australia, Africa and South America. Such distribution is said to be discontinuous distribution. It can be explained, that these individuals might have present continuously. But due to changes in climatic conditions between the above continuity they became extinct.

dipnoi lungfish
Figure 604.2: (A) Australian Lungfish, (B) South American Lungfish, and (C) African Lungfish

5. FAUNA OF NORTHEREN HEMISPHERE

The continents, North America and Eurasia of northern hemisphere consist of same fauna. It is mainly because these two continents are connected by land isthmus called bearing isthamus. Hence the animals from North America are migrated to Eurasia and vice versa. But now the 56 miled bearing land isthmus was recently converted into aquatic isthamus.

Thus the geographical distribution of animals supports the theory of organic evolution.

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Last modified on Thursday, 21 February 2019 22:02
Read 725 times
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