Australian region,one of the zoogeographical realms

Australian region

Introduction

Zoogeographical realms : Based on the faunal peculiarity & the pattern of animal distribution , the earth surface can be divided into several megafaunal zones .

The term “realm” was first proposed by Lydekker He divided earth’s surface into 3 realms 1. Arctogaea 2. Notogaea 3. Neogaea

Arctogaea is the largest division which includes the continuous land mass of northern hemisphere

Arctogaea is further subdivided into 4 regions 1. Palaearctic 2. Nearctic 3. Ethiopian 4. Oriental regions Notogaea includes Australia Neogaea includes South America

Sclater (1867) : six geographical region based mainly distribution of birds

1. Palearctic region : consist Europe , temperate regions of Asia & the northern temperate part of Africa lying north of atlas mountains.

2. Ethiopian or western palaeotropical region : consist of Africa & southern Arabia .

3. Indian or middle palaeotropical region : consist of tropical Asia & the associated continental islands.

4. Australian or eastern palaeotropical region : consist of Australia , New Guinea & Tasmania.5. Nearctic or North American regions : consist of north

America , north to central Mexico .6. Neotropical or south American region : consist of south & central America & southern Mexico.

Zoogeographic realms

Largely based on Wallace’s analysis of the ranges of families of mammals

Alfred Russel Wallace in his famous work “Geographical Distribution of Animals (1876)

Today the widely accepted system of zoogeographical classification is that of Wallace

Six realms 1. Palaearctic region 2. Nearctic region 3. Neotropical region 4. Ethiopean region 5. Oriental region 6. Australian region

Faunal RegionsPalearcticNearctic

Neotropical Ethiopian Oriental Australian

Australian region

Geographical & Climatic features

This region consist of Australia , New guinea , Tasmania & Indonesia islands

Some authors include New Zealand also in this region and call the region Australasia , instead of Australia

The region is a mixture of tropical and temperate zones.

Northern part --- large tropical region Southern part---- temperate region

Australia , New Zealand & New Caledonia are all portions of the ancient supercontinent of Gondwana

Which started to break into smaller continents in the Cretaceous era , 130-65 million year ago

New Zealand broke away first , more than 80 million years ago Australia finally broke apart from Antarctica about 45 million

year ago.

Australia moved northward to desert latitude , the continents become hotter & drier As a result new drought – tolerant and fire resistant flora , dominated by Eucalyptus , Casuarina , Acacia , Grasses and Scrubs Presently , Australia is the smallest , the driest and the flattest ( lowest in elevation ) continent.

Faunal characteristics

From a zoological point of view , Australia is a distinct region with a common evolutionary history and very unique animals .

Some of these animals are common to the entire area , others specific to particular parts but sharing a common ancestry .

Australia & New Guinea are distinguished by their marsupial mammals , including Kangaroos , possums and Wombats .

The last remaining monotreme mammals , the echidnas & the platypus are endemic to Australia .

Sub - regions

Australian region is further subdivided into three sub regions 1. Austro- Malayan sub region (islands of Malayan Archipelago , New Guinea and Solomon islands ) 2. Australian sub region ( Australia and Tasmania ) :

3. Polynesian sub region ( islands of Polynesia and sandwich islands )

Thank you by Anand P P