Hotspots

Introduction

Biodiversity refers to the occurence of various types of ecosystems and species of organisms with a whole range of their biotypes and genes that are adapted to different climates, along with their interactions and processes. Walter G. Rosen in 1985 coined the term  biodiversity. Later, the term was popularized by Edward Wilson in 1992. 

Biodiversity hotspots were identified by Norman Myers. These hotspots are the regions that are rich in biodiversity, and are declared sensitive due to direct or indirect human interference. 

Factors determining Hotspots

The factors determining hotspots are: 

• Number of species diversity

• High degrees of endemism

• Degree of exploitation

• Degree of threat to habitat

Based on the above criteria there are three major biodiversity hotspots in India they include:

The Himalayas

The Himalayan mountain ranges nearly 750,000 km². This region is marked by a record of having about 163 endangered species which comprises one horned Rhino, Wild Asian Water Buffalo and also 10,000 plants species out of which about 3160 are known to be endemic.

The Western Ghats

This region is situated along the western edge of peninsular India, covering most of the forests and rainforests. About 325 globally threatened species of fauna, flora, reptiles, amphibians, birds and fish houses in this region. Out of which there are about 229 species of plants, 31 species of mammals, 43 amphibians species, 15 species of birds, 5 of reptiles species and 1 fish species. UNESCO states that among these 325 globally threatened species about 129 are identified as Vulnerable, 145 as Endangered and 55 as Critically Endangered species. 

The Indo Burma

It covers a distance of 2,373,000 km². This hotspot is better known for the endemic freshwater turtle species, most of which are on the verge of extinction, due to extreme habitat loss and over harvesting. This region comprises about 1,300 different bird species and about 6 large mammals species.

All over the world there are about 34 hotspots.

Endangered Organisms

Organisms that are facing a high risk of extinction in the wild in the near future, due to loss in their habitats and excessive predation or poaching are known as endangered organisms. According to IUCN India accounts for 7-8 percent of endangered species comprising 45,000 species of plants and about 91,000 species of animals. 

The six major endangered fauna and flora of India are:

• Fauna

• The Royal Bengal Tiger

• The Snow Leopard

• The Great Asiatic Lion 

• The Indian Rhino

• Nilgiri Tahr 

• Red panda

• Flora 

• Milkwort

• The Malabar Lily

• Indian Mallow 

• Ebony tree

• Assam Catkin Yew

• Bentinckia nicobarica

Extinction 

Once a species becomes extinct all of its genetic heritage is lost. Thus, the species have to evolve into new species in order to survive the environmental changes or changes in genetic inheritance. The IUCN Red List accounts for the extinction of about 784 species (338 vertebrates, 359 invertebrates, and 87 species of plants) in the last 500 years. Recent studies show that in the last twenty one years a total of 27 species have disappeared. This record shows that extinction across taxa is not random, rather some groups like that of amphibians appear to be more vulnerable to extinction. 

About more than 3 billion years ago, since the origin of life on earth there were nearly five episodes of mass extinction of species. The recent species extinction rates are about 100 to 1,000 times faster than in pre-human times. 

Causes of Extinction

The increased rates of species extinction that the world is facing is mainly due to human activities. There are majorly four reasons for extinction, and they are commonly known as  “The Evil Quartet”. They are discussed as follows:

Habitat Loss and Fragmentation

This is the main reason for driving flora and fauna to extinction by destruction of their natural habitats like filling wetlands, deforestation, plowing grasslands, construction work for development of dams, reservoirs etc. Fragmentation of habitats like plantations, orchards, urban areas etc, results in splitting of complex interactions amongst species, destruction of species in cleared regions etc, migrated animals go astray and are killed. The major extinction that occurred due to habitat loss was of “The Amazon Rainforest” also known as “lungs of the planet” which previously used to cover 14% of the earth’s land and now covers only 6%, millions of species there are being cleared and cut for cultivating soybeans and developing grasslands for raising beef cattle.

Over-Exploitation 

Enormous exploitation of both plants and animals species, reduces the size of its population and it thus, becomes vulnerable to extinction. Some examples of animals that are being extinct due to over-exploitation by humans are Dodo, Passenger Pigeon, Steller’s Sea Cow and three subspecies of tiger (Bali, Caspian and Javan). 

Alien Species Invasion

Alien species are often introduced for their economic uses. They become invasive and drive away local species. E.g. Introduction of Nile Perch in lake Victoria of South Africa killed and eliminated about 200 native species of Cichlid Fish, further introduction of Lantana camara  as an ornamental plant in many parts of India has replaced many species in the forests.

Co-Extinction

Some mutualistic relationships occur in nature, in which extinction of one species will automatically cause the extinction of the other e.g. Pronuba moth and Yucca plant.

Red Data Book

It is a document established in 1948 by IUCN, with an aim to maintain a complete list of every rare and  endangered species of both plants and animals that exists within a state or a country.

Objectives of Red Data Book

• It provides scientific records on the status of species and subspecies at a global level

• The information provided by this book helps the Zoological and National parks to use them and upgrade vital policies like parks regulation in a timely manner

• It helps in evaluating the population of a particular species

• By the help of this book we estimate the risk of taxa becoming extinct

Categories of Red List

The IUCN listed about 9 categories of Red List they are as follows:

• Extinct: this taxon has completely disappeared from earth e.g. Dodo

• Extinct in wild: this means that the taxon is absent in any of its natural habitat in the wild

• Critically endangered: taxon facing high risk of extinction in the wild, and can become extinct at any moment in near future e.g. Pygmy Hog

• Endangered: the members of this taxon are facing high risk of extinction in the wild in near future due to reduced habitat e.g. Lion tailed Macaque

• Vulnerable: the population of the members is presently sufficient but is undergoing reduction due to some factors, and faces the risk of extinction in medium term future e.g. Clouded Leopard

• Near threat: the taxon is likely to become endangered soon.

• Low risk: these are the threatened species and are having low risk of extinction

• Data deficient: no sufficient data is present to assess its risk of extinction

• Not evaluated: taxon is not evaluated for the risk of extinction

Conclusion

Biodiversity is not evenly distributed on earth. Some areas have habitat in small proportion and some have in large proportion this refers to hotspots. We must try harder to increase the population of endangered species and to prevent more animals from being extinct.