Biodiversity in Simple Terms

I’m Yash Srivastava a budding Environmentalist pursuing my graduation in Environmental Science. While studying Ecosystems, I was intrigued by the term "Biodiversity-The variety of life" or "The web of life" and its recurrent usage across all topics. This inquisitively forced me to research further on Biodiversity and pen my first blog.

Sir David Attenborough once quoted for Biodiversity - "It is that range of biodiversity that we must care for - the whole thing rather than just one or two stars".

I feel in today's world, there is a need for the conservation of our Biodiversity, by that I mean PROTECTION, PRESERVATION and MANAGEMENT of various ecosystems and natural habitats, thereby ensuring that they are healthy and functional.

My blog is an attempt to explain Biodiversity in simple terms so that we become aware of what it means and how important it is for our survival.

Introduction to Biodiversity

Biodiversity is the abbreviated word for biological diversity. The term biodiversity is a combination of two words where "BIO"-means life and "Diversity"-means variety. 

So, summing up these words, biodiversity can be defined as the wide variety of living organisms on earth.

Fig. 1 Biodiversity

In scientific terms, biodiversity can be defined as the variety of all organisms on earth on various levels from genes to ecosystems and can encompass the evolutionary, ecological, and cultural processes that sustain life.

 

History of Biodiversity

The term "biological diversity" was first used by James Arthur Harris in “The Variable Desert", Scientific American in the year 1916.

The term "natural diversity" was introduced in the year 1974 by John Terborgh.

In 1980, the term "biological diversity" was introduced to the scientific community in a book by Thomas Lovejoy thereby, making it quite common.

Also, in 1985, the term "biodiversity" was coined by Walter. G Rosen who is also known as the "Father of the Biodiversity”.

In 1988, the term was applied in a publication and till now, it is being published in educational books and further research.

 

Types of Biodiversity

There are several levels of biodiversity, each indicating how diverse the genes, species and resources are in a region.

1. Genetic Diversity

Genetic Diversity is the diversity or variability within species, community or assemblage. In general, genetic diversity is a factor enabling natural selection to others. Genetic diversity is important because it helps maintain the health of a population, by including alleles (specific forms of a gene variant) that may be valuable in resisting diseases, pests and other stresses. Genetic diversity is a vital element of biodiversity. One example of genetic diversity could be Human beings.

Fig. 2 Genetic Diversity in Humans

 2. Species diversity

Species diversity is a function of species richness, the number of species in a given locality and species evenness, the degree to which the relative abundances of species are similar. In general, species diversity can be explained as the variety of species and abundance of species. 

Fig. 3 Species Diversity in Tropical Rainforest

One example of species diversity is the tropical rain forest which contains half of the world's species.

· 40% of the world's 2,75,000 species of flowering plants are present in the tropical areas.

· 30% of total bird species are present in the tropical areas.

The species richness of the tropical rainforest is mostly due to the constant environmental conditions.

3. Ecosystem Diversity

Ecosystem Diversity is the diversity at the ecological or habitat level which includes the interaction of the abiotic factors (non-living) and biotic factors (living) in the various ecosystems.

Ecosystem Diversity is the largest scale of biodiversity and within each ecosystem, there is a great deal of both species and genetic diversity. Examples related to the ecosystem diversity could be any ecosystem like desert or grassland or tropical rainforest ecosystem.

Fig. 4 Ecosystem Diversity

 Ecosystem Diversity consists of three categories: -

A. Alpha Diversity (α-diversity): Alpha diversity can be defined as the species diversity of a homogeneous habitat or in other words number of species in a small area. It is also called “within habitat diversity” by Mac Arthur and Wilson.

Fig. 5 Alpha Diversity

B. Beta Diversity (β-diversity): Beta diversity can be defined as the degree of change in species from one habitat to the next. It refers to “between habitat diversity”.

Fig. 6 Beta Diversity

C. Gamma Diversity (γ-diversity): Gamma diversity can be defined as the diversity of larger unit such as the island or landscape or it is the diversity of the group of an area of α-diversity.

Fig. 7 Gamma Diversity

Levels of Biodiversity

Ecosystem Diversity is the diversity at the ecological or habitat level which includes the interaction of the abiotic factors (non-living) and biotic factors (living) in the various ecosystems. 

Biodiversity can be represented at various levels which are as follows:

A. Biodiversity at Global Level: A huge number of species are still unknown on this earth. The tropical rainforests have species of plants, insects, animals. They are the earth's largest storehouses of biodiversity.

· About 2.1 million species have been identified to date.

· About 70% of all known species are invertebrates while about 15% are planted.

· About 40% of terrestrial plants and 25% of vertebrate species are endemic* and found in these hotspots**.

· It has been estimated that 50,000 endemic plants, which comprise 20% of global plant life, probably occur in only 18 hotspots in the world.

*Endemic Species: Endemic Species refers to a species that is      native to where it is found. Some examples of endemic plants and animals can be Lemur in Madagascar and Hawaiian hibiscus, native to Hawaii.

Fig. 8 Lemur is found in Madagascar and is considered as an endemic specie.

**Biodiversity Hotspots: Biodiversity Hotspots can be defined as the bio-geographic region that is both a significant reservoir of biodiversity and is threatened with destruction. Currently, 36 biodiversity hotspots are present in the world out of which four are in India - Western Ghats, the Himalayas, Indo-Burma Region and Sunda land

Fig. 9 Biodiversity Hotspots of the World

 B. Biodiversity at National Level: Every country is characterized by its biodiversity depending mainly on its climate. India has a rich biological diversity of flora and fauna.

· Overall, 6% of the global species are found in India.

· It is estimated that India ranks 10th among the plant-rich countries of the world.

· India ranks 11th in terms of the number of endemic species of higher vertebrates.

· India ranks 6th place among the centres of diversity and origin of crops.

· The total number of living species identified in our country is 1,50,000.

· India is also one of the 12 mega-biodiversity countries in the world. 

 

Biodiversity has many more topics like Values of Biodiversity,  Threats to Biodiversity and Conservation of Biodiversity, which I’ll be covering in my coming blogs.

 

 References:

· Images from Internet, Unesco.org

· References from National Geographic

· References from International Institute for Environment and Development.