Zoogeography and factors affecting animal distribution

Geographical distribution of animals

1. Zoogeography and Factors affecting animal distribution

2. Zoogeography Branch of biology concerned with the distribution of all the animals, invertebrates and vertebrates, the terrestrial and aquatic, over the whole world. Distribution can be studied at 3 levels- Geographical (over the whole world) Regional (in selected segments of the world) Local (geographical distribution of a species in relation to each other and in relation to ecology and evolution)

3. Philip Sclater (1858) and Alfred Wallace (1876) identified the main zoogeographic regions of the world used today- Palearctic region Nearctic region Neotropical region Ethiopian region Oriental region Australian region

4. Palearctic region

5. Includes northern part of Old World. Extends over whole of Europe, China, Japan, North Sahara, Siberia, Mediterranean Sea zone of North Africa and Manchuria, south-west Asia, North of Himalayas and the north of Arabia. Bounded by sea to the west, east and north and by Sahara and Himalayas to the south. Climate is chiefly temperate with an arctic fringe. Includes both wet and dry open Steppe land, large areas of coniferous forests and a fringe of tundra; deciduous forest; wide variation of temperature and great fluctuation in rainfall. Fauna exhibits variations in the climatic and vegetational subdivisions. It is richest in warmer areas and diminishes northward. This region possesses a total of 135 families of terrestrial vertebrates (33 families of mammals, 68 birds, 24 reptiles, 10 amphibian , 13 freshwater fishes.) Subdivided into – European sub region Mediterranean sub region Siberian sub region Manchurian sub region

6. Llama Red panda Moose European salamander Giant Asian salamander Chinese alligator

7. Hedge sparrow Rhacophorus sp. Heron Red fox Giant panda

8. Nearctic region

9. Includes North America above tropics, Greenland, Iceland and Mexican plateau. Except for a narrow strip of Central America it is completely cut off from all other regions by sea. Resembles Palearctic region in climatic conditions. Exhibits extreme variations in temperature and varied climatic conditions. Has extensive mountain ranges in the west running from north to south. North is the arctic belt of Greenland, followed by coniferous belts, deciduous or mixed forests, extensive grasslands and arid zones. The region is much less rich in fauna than other regions, mainly transitional representing a mixture of fauna of Palearctic and Neotropical regions. This region possesses a total of 120 families of vertebrates (26 families of mammals, 4 birds, 21 reptiles, 14 amphibian , 24 fishes.) Subdivided into- Californian sub region Rocky Mountain sub region Alleghany sub region Canadian sub region

10. Pocket gopher Pocket mouse Kangaroo rat Pronghorn Shrew Turkey Garpike Bowfin

11. Axolotl Musk turtle Pit viper Gila monster American salamander Flying squirrel Red deer Beaver

12. Neotropical region

13. Includes South America, Central America, tropical lowland of South Mexico and West Indies. Presents tropical conditions except southern part of South America which constitutes south temperate zones. Extensive rain forests or evergreen forests are found in Amazon valley, tracts of dry forests or grassy plains in Savannah and Argentina, and sub-desert areas are present in western South America. West has long range of Andes which has high mountains. Fauna is both distinctive and varied. Rich in endemic families of all classes. The region has 155 families of terrestrial vertebrates, out of which 33 are endemic. Subdivided into – Chilean sub region Brazilian sub region Mexican sub region Antillean sub region

14. Tapir Anteater Armadillo Sloth Opossums Electric eel

15. Marmoset Tarmarin Tree porcupine Agouti Paca Rhea Toucan Curassows Cock-of-the-rock

16. Ethiopian region

17. Includes Africa south of Sahara, Madagascar and South Arabia. Has land continuity with its northern neighbor (Palearctic) but the Sahara desert acts as an effective barrier between the two. Remaining sides are surrounded by sea. Africa is a tropical country. It has large blocks of lofty evergreen forests in the equatorial region, mountainous region and wide grassy plains in the eastern part. Southern part is warm temperate with mixed vegetation. Vertebrate fauna is rich and well marked with a number of endemic genera and families present because of extensive equatorial forests and swamps as well as grasslands. There are 161 families of terrestrial vertebrates in this region. Subdivided into- East African sub region West African sub region South African sub region Malagasy sub region

18. Slender loris Hippopotamus Gorilla Baboon

19. Ostrich Typhlops sp. African elephant Giraffe Spiny lizard Black bear

20. Aardvark Golden mole African lungfish Turacos sp. Xenopus sp.

21. Oriental region

22. Includes India, south of Himalayas, Myanmar, Thailand, Malaysia, Sumatra, Java, Philippines and South China. Bounded by Himalayas in the north and in the west separated from Palearctic by mountains and desert of eastern Iran, but there is no physical boundary in the south-east corner. Known for its varied physical features. Northern India is temperate, eastern part including Myanmar and N.E. Asia has rain forests; western penninsula is part desert and southern part of India has tropical forests. Fauna exhibits considerable resemblance with that of Ethiopian region. Subdivided into- Indian sub region Indo- China sub region Ceylonese sub region Indo- malayan sub region

23. Gavialis sp. Orangutan Big-headed turtle Gibbons Colugo

24. Peacock One horned rhinoceros Shield tail

25. Indian elephant Tree shrew Tarsier Spiny dormouse

26. Australian region

27. Includes Australia, New Zealand, New Guinea, Tasmania, Moluccas and neighboring islands. Region is partly tropical and partly temperate. New Guinea is tropical and mostly covered with rain forests. Northern part of Australia is tropical but most of the interior is arid. Tasmania is cool and temperate. Fauna is unique and primitive. Most peculiar feature is the absence of higher placental mammals and the region contains many primitive forms, marsupials and monotremes are found only in this region. Subdivided into- Austro- malayan sub region Australian sub region Polynesian sub region New Zealand

28. Marsupial mouse Marsupial mole Flying phalanger Kangaroo Wombat Spiny anteater Australian lungfish Skink Tiger snake

29. Duck billed platypus Cockatoo Loris Pygmy parrot Cassowary Emu Honey sucker Lyre bird

30. Animal Distribution Distribution of animals in space Geographical distribution Bathymetric distribution Distribution of animals in time or geological distribution Two aspects of animal distribution- Patterns of animal distribution- Cosmopolitan distribution Discontinuous distribution Bipolar distribution

31. Factors affecting distribution Animal are found to occupy all diverse habitats wherever life is possible but the animals found in different regions, different areas and different localities are not identical. These exhibit several complications in their distribution pattern. The irregularities in distribution are mainly on account of faulty or non-uniform dispersal of animals which is governed by several factors. These factors which control or check migration and dispersal of animals are known as barriers.

32. Barriers to dispersal Barriers are the factors which hinder in the normal distribution of animals. Maybe either vast tracks of territory inhospitable to a species or narrow bands of environment that may act as narrow fences, preventing species migration to new regions. All natural barriers can be categorized into 3 categories- Physical barriers Climatic barriers Biological barriers

33. Physical barriers Topographical barriers Large bodies of water and land masses Impurity and lack of salinity of sea water, and Vegetative barriers Sheer distance Mozambique Channel

34. Climatic or Ecological barriers Temperature Moisture Amount of light Biological barriers Sedentary habit Home range or territoriality

35. Means of dispersal Natural rafts and driftwoods Wind Storms Land bridges Transportation by animals capable of flight Human agency

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