A. Geographical Boundaries:The Neotropical Realm includes South and Central America, the lower part of Mexico, and the West Indies. It is connected to the Nearctic Realm via the Central American Isthmus, while its other boundaries are defined by surrounding seas.
B. Subdivisions:This realm is divided into four sub-regions:
Chilean Sub-region: Encompasses the western part of South America, including Peru, Bolivia, and the Andes mountain range. This region has relatively low faunal diversity.
Brazilian Sub-region: Covers the entire country of Brazil and extends up to the Panama Canal. It is exceptionally rich in biodiversity.
Mexican Sub-region: Located between North and South America, this sub-region includes the northern side of the Panama Isthmus and supports significant faunal diversity.
Antillean Sub-region: Comprises the entire West Indies, except Trinidad and Tobago, and is characterized by a relatively low number of animal species.
C. Climatic Conditions: Most of this region consists of tropical dry lands, while the southern part of South America experiences a temperate climate.
D. Ecological Conditions:
The Amazon Valley hosts vast tropical rainforests.
The temperate regions contain savannahs and grasslands.
The western part of South America is arid, with desert-like ecosystems.
Argentina is largely covered by grasslands.
E. Characteristic Vertebrate Fauna:
Fish: This region has 120 genera spanning three families—Polycentridae, Gymnotidae, and Trigonidae. Notable species include Lepidosiren, eel, and catfish.
Amphibians: Includes Caecilia, Siphonopsis, Hyla, salamanders, frogs, and toads.
Reptiles: Notable species include snakes (Dromicus, Boa, Epicrates), geckos, alligators, and turtles such as Chelys.
Birds: Around 700 genera of birds are recorded here, including rheas, tinamous, screamers, thrushes, and parakeets.
Mammals: The region has 32 recorded families, including opossums, caenolestes, sloths, armadillos, rodents, American tapirs, bats, spider monkeys, and llamas.
Ethiopian Realm
A. Geographical Boundaries: The Ethiopian Realm consists of Africa south of the Tropic of Cancer, most of the African mainland, the southern part of the Arabian Peninsula, and Madagascar.
B. Subdivisions:This realm is divided into four sub-regions:
East African Sub-region: Includes the hot and dry regions of Africa and the Arabian Peninsula.
West African Sub-region: Covers the western parts of the Ethiopian realm, extending up to the Congo region.
South African Sub-region: Comprises the entirety of southern Africa.
Malagasy Sub-region: Includes the island of Madagascar.
C. Climatic Conditions:The climate is mainly temperate, but remains hot for most of the year.
D. Ecological Conditions:
The equatorial and West African regions contain rainforests along large rivers.
Most of the remaining areas consist of dry deciduous forests.
The northern and southern regions are largely desert landscapes.
E. Characteristic Vertebrate Fauna:
Fish: Includes catfish and lungfish such as Protopterus and Polypterus, along with various freshwater species.
Amphibians: Features Xenopus and several species of caecilians. The group Caudata (salamanders) is completely absent.
Reptiles: Includes snakes (Leptorhynchus, Ramnophis), lizards (Monotrophis, Cordylus, Agama, Chameleon), and various turtle species.
Birds: Comprises 67 recorded families, including ostriches, cuckoos, parakeets, eagles, kites, pigeons, and hornbills.
Mammals: There are 51 recorded mammalian families, with 15 endemic ones. Notable species include zebras, gorillas, antelopes, leopards, two-horned rhinoceroses, hippopotamuses, lemurs, gnus, baboons, lions, giraffes, chimpanzees, and African elephants (Loxodonta).
Oriental Realm
A. Geographical Boundaries:The Oriental Realm includes most Asian countries located south of the Himalayas. It encompasses India, Burma, Indochina, Malaysia, Sumatra, Java, Bali, Borneo, and the Philippines.
B. Subdivisions:This realm is divided into four sub-regions:
Indian Sub-region: Covers the entire Indian subcontinent from the base of the Himalayas.
Wallace (1876) separated this sub-region based on molluscs, reptiles, birds, and mammals.
Mahendra (1942) further classified it into 10 divisions based on floral and faunal distribution.
The Indian sub-region includes:
Northern India’s dry and semi-dry areas
Western Himalayas
Southern Burma
The Ganges Plateau
Southern India below 20° latitude
The Ganges Plateau above 20° latitude
Tribankur
Sri Lanka (Ceylon)
Nicobar Islands
Andaman Islands
Ceylonese Sub-region: Covers parts of the Indian Peninsula and Sri Lanka.
Indo-Chinese Sub-region: Includes South China, Burma, Thailand, and Indochina.
Indo-Malayan Sub-region: Comprises the eastern part of the Oriental Realm, including Malaysia and the East Indies.
C. Climatic Conditions:Most of the region experiences a temperate climate, with an annual rainfall exceeding 1500 mm.
D. Ecological Conditions:
Eastern parts contain dense rainforests.
Western regions have desert landscapes.
Other areas feature moderate forests.
E. Characteristic Vertebrate Fauna:
Fish: Includes various types of carp, catfish, notopteridae, osteoglossids, and cypriniformes.
Amphibians: Consists of diverse anurans, some salamanders, and caecilians.
Reptiles: Features numerous snakes (vipers, pit vipers, kraits), lizards (Gekko, Agamidae, Varanus, Chameleons), and turtles from the Platysternidae family. Crocodiles and gavials are also present.
Birds: Includes pigeons, owls, finches, pheasants, peacocks, and sarus cranes.
Mammals: Notable species include shrews, rabbits, dogs, cats, boars, rodents, flying lemurs, elephants, oxen, tigers, orangutans, gibbons, tapirs, pangolins, and Rhinoceros unicornis. Among 30 recorded mammalian families, only four are endemic.
Australian Realm
A. Geographical Boundaries: The Australian Realm includes Australia, New Zealand, New Guinea, Tasmania, and several nearby islands.
B. Subdivisions: This realm is divided into four sub-regions:
Austro-Malayan Sub-region: Covers the Malay Archipelago, including New Guinea, the Moluccas, and the Solomon Islands.
Australian Sub-region: Includes Tasmania and mainland Australia.
Polynesian Sub-region: Comprises Polynesia and the Sandwich Islands.
New Zealand Sub-region: Encompasses New Zealand, Norfolk Island, Auckland, Campbell.
C. Climatic Conditions:The Australian Realm experiences both hot and temperate climates. The average annual rainfall is approximately 75 mm.
D. Ecological Conditions:This region features diverse ecosystems, including rainforests, grasslands, and eucalyptus forests.
E. Characteristic Vertebrate Fauna:
(i) Fishes:Notable fish species include the Neoceratodus lungfish, Osteoglossids, and members of the Gadopsidae family.
(ii) Amphibians:The Xenorhinidae family is found exclusively in New Guinea.Other significant amphibians include Pseudophryne, Pachybatrachus, Helioporus, and Pelodyrus.A total of 11 amphibian families are recorded in this realm.
(iii) Reptiles:Important snake families include Pythonidae and Elapidae.Prominent lizard families are Pygopodidae, Aprasia, and Liadidae.The Sphenodon, belonging to the Rhynchocephalidae family, is a well-known relict reptile found in New Zealand.
(iv) Birds:This realm is home to 906 recorded bird species, including the cassowary, lyrebird, magpie, emu, kiwi, scrub-bird, and bowerbird.
(v) Mammals:
Unique mammals include Ornithorhynchus (platypus) and Tachyglossus (echidna).
Marsupials are highly diverse, with notable species such as kangaroos, dasyures, Dendrolagus (tree kangaroo), and Petaurus (flying opossum).
Other remarkable mammals include the Tasmanian wolf (thylacine) and various possum species.acquarie Islands.
