Zoogeographical regions
Sclater (1857) was the first one to give concepts of zoogeography and divided the continental masses into six Realms based on his studies on the bird fauna under two Creatio or centres of Creation, namely, Palaeogeana (Old world) and Neogeana (New world).
Creatio PALAEOGEANA (Old World)
Realms PALAEARCTIC (Temperate Eurasia)
AETHIOPIAN (West Paleotropic). Africa.
INDIAN (Middle Paleotropic). Tropical Asia.
AUSTRALIAN 9East Paleotropic). Australia, New Guinea, Tasmania.
Creatio NEOGEANA (New World)
Realms NEARCTIC (North America). Greenland, North America up to Mexico.
NEOTROPICAL (South America). South America south of Mexico.
T.H. Huxley (1868) grouped different regions into 3 divisions as follows:
NEOGEA (Neotropical).
NOTOGEA (Australian).
ARCTOGEA (Rest of the Word).
A.R.Wallace (1876), who is considered father of modern zoogeography agreed with Sclater’s classification but proposed the name ORIENTAL instead of INDIAN and AFRICAN instead of ETHIOPIAN regions because the earlier names represented countries and not the zoogeographical regions.
The widely accepted modern classification of land masses into regions is given below which is based on Wallace (1876) and Darlington (1957).
1. Realm MEGAGEA
1. Region PALEARCTIC (Europe, Russia, Mediterranean).
2. NEARCTIC (North America up to the middle of Mexico).
3. AFRICAN (=ETHIOPIAN) (Africa south of Sahara).
4. ORIENTAL (Tropical Asia south of 30o latitude).
2. Realm NEOGEA
5. Region NEOTROPICAL (South America, tropical Mexico and Caribbean Islands).
3. Realm NOTOGEA
6. Region AUSTRALIAN (Australia, Tasmania, New Guinea and New Zealand).
distribution
Animals are not uniformly distributed on land and in freshwater. They are restricted to certain places by several factors such as climate, food, shelter, flora and fauna etc. Generally distribution can be classified into three categories, namely, Continuous, Discontinuous and Bipolar distribution.
1. Continuous distribution. Eurytopic or wide-ranging animals are adapted to a wide variety of environmental conditions and are not specific to any particular type of food or may have special power to cross barriers either by flight, rafting or swimming and adapt to new environmental conditions.
2. Discontinuous distribution. When continuity of distribution of a species is broken by uninhabited areas which are sometimes very large stretches of oceans. There are primarily four reasons why animals are distributed in widely separated areas.
Examples:
Peripatus (Phylum Onychophora) has 75 species distributed in Southeast Asia, East Indies, Australia, New Zealand, Africa, South and Central America
3. Bipolar distribution. Some species because they are adapted to the cold arctic cl
Dr. K. Rama Rao
Govt. Degree College
TEKKALI; Srikakulam Dt: A. P.
