Meaning of Biodiversity

The term biodiversity was coined by Walter and Rosen (1985) and is the abbreviated word for Biological Diversity. Life originated on earth almost four billion years ago and nature took more than 1 billion years to develop this wide and complex spectrum of life on earth. Scientists believe that the total number of species on earth is between 10-80 million (Wilson 1988) of which 1.4 million species have been enlisted so far. Biological diversity is abbreviated as biodiversity which refers to the sum of species, populations, communities, and ecosystems. It may also be defined as the variety and variability among the living organisms (unicellular fungi, protozoa, bacteria, and multi-cellular organisms such as plants, fishes, and mammals) and the ecological complexes (including gens, habitats, and ecosystem) in which they occur.

However, we are losing this heritage of millions of years at a very fast rate. The reduction in diversity in life forms is bound to have grave consequences for the entire living world. It has become extremely important to study simultaneously the various life forms on earth and the causes of their destruction. Biodiversity is the total variety of life on our planet.

The biosphere (the web of life that lives within and depends upon the inorganic spheres) constitutes a vital life support system for man and its existence in a healthy and functional state is essential for the existence of the human race.

  • Biodiversity is a term made up from two words…

Bio- Life

Diversity: Variety

(The term biodiversity refers to the variety of life on Earth.)

  • Biodiversity refers to the variety of living species on Earth, including plants, animals, bacteria, and fungi.
  • Variety of life forms found in a particular region.
  • 1.7 – 1.8 million organisms are present on earth.
  • These organisms are different from each other in shape, size, color, pattern, internal structure, habitat, nutrition, behavior, external appearances, etc. (All are interrelated)

Some of the Important Definitions of Biodiversity are given here:

As defined in the Convention on Biological Diversity signed at Earth Summit held in Rio De Janeiro
(Brazil) in 1992
by 154 countries, Biodiversity was defined as “the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic eco-systems and the ecological complexes of which the area part- this includes diversity within species, between species and of the ecosystem.”

According to IUCN in 1998, “the variety and variability of species of their population, the variety of species of their life forms, the diversity of the complex association with species with their interaction and their ecological process which influences perform.”

Biodiversity is the variety of life in all its forms, levels, and combinations. It includes species diversity, genetic diversity, and ecosystem diversity (International Union for Conservation of Nature and Natural Resources—IUCN, United Nations Environment Programme—UNEP and World Wildlife Fund—WWF 1991).

According to U.S. Congressional Biodiversity Act – Biological Diversity is the variety and variability among living organisms and the ecological complexes in which they occur and encompasses ecosystem diversity, species diversity, and genetic diversity.

Types of Biodiversity

1. Ecosystem Diversity

2. Genetic Diversity

3. Species Diversity

1. Ecosystem Diversity

Ecological biodiversity refers to the variations in the plant and animal species living together and connected by food chains and food webs.

Eg. Diversity in different ecosystems like deserts, rainforests, mangroves, etc included ecological diversity.

Different habits, niches, and species interactions.

An assemblage of species living in the same area and interesting in an environment.

The broad differences between ecosystem types and the diversity of habitats and ecological processes occurring within each ecosystem type constitute ecosystem diversity.

Biodiversity is considered at the ecosystem level as it determines the variety and number of species in particular ecosystems through the different habitats for biological communities and biological processes operating in each natural ecosystem.

Ecosystem diversity has three outlooks

a) Alpha (α) Diversity: It is the biodiversity within a particular region, community, or ecosystem. It is usually expressed by the number of species in that ecosystem. This can be calculated by including the number of distinct groups of organisms (taxa) within the ecosystem (Families, genera, and species).

b) Beta (β) Diversity: Beta diversity is a measure of biodiversity which works by matching up the species diversity between ecosystems or along environmental pitches. This involves matching the number of taxa that are exclusive to each of the ecosystems. It depicts a range of communities due to the substitution of species that takes place due to the occurrence of diverse microhabitats, niches, and environmental conditions.

c) Gamma (γ) Diversity: It illustrates the diversity of habitat over a total geographical area. It is a product of component ecosystems (alpha diversity) and the between component ecosystems (beta diversity). Gamma diversity can be expressed in terms of the species abundance of component communities as follows;

γ = s1 + s2 – c
s1 = the total number of species recorded in the first community
s2 = the total number of species recorded in the second community
c = the number of species common to both communities

2. Genetic Diversity
Image by DCStudio on Freepik

Genetic Diversity is the variation in genes and genotypes within a species.

Eg. Every human looks different from each other.

Different genes and combinations of genes within the population.

Allows the population of a species to adapt to environmental changes.

Genetic diversity is the variety present at the level of genes.

Genes, made of DNA (right), are the building blocks that determine how an organism will develop and what its traits and abilities will be.

Genetic diversity can be measured at many different levels including population, species, and community.

The range of genetic material present in the population of a single species.

The Mauritian Pink Pigeon had a population of 10 in 1991. Because of conservation efforts, the population is rising. All pink pigeons alive today originate from this small group.

Human beings genetically belong to the homo-spiens group and also differ in their characteristics such as height, color, physical appearance, etc., considerably.

This genetic diversity is essential for the healthy breeding of a population of species.

Genetic diversity refers to the variation of genes within a population or species. Genetic variation is vital for a vigorous breeding population of a species. Each and every individual of any animal or plant species vary widely from other individuals in its genetic make-up due to the huge number of grouping possible in the genes that give every individual specific characteristic.

Genetic diversity can be measured using a variety of DNA-based and other techniques.

The genetic material of microorganisms, plants, and animals contains information that determines the characteristics of all species and individuals that make up the diversity of the living world. Thus, genetic diversity refers to the differences in genetic make-up between distinct species and to genetic variations within a single species. In simple terms, genetic material dictates whether we have blue or brown eyes, blond or black hair, and are tall or short. It also determines whether an individual animal or plant has the ability to survive in a particular habitat or under particular environmental conditions, some plants, for example, are able to grow in saline water as a result of genetic variation.

– New genetic variation is produced in populations of organisms that can be reproduced sexually by recombination and in individuals by gene and chromosome mutations. The large differences in the amount and distribution of genetic variation can be attributed in part to the enormous variety and complexity of habitats, and the different ways organism obtain their living (Benny Jseph, 2009).

3. Species Diversity
Image by DCStudio on Freepik

Species Diversity is the variety of species within a habitat or a region. It is the biodiversity observed within a community.

Eg. Every human looks different from each other.

Different kinds of organisms, relationships among species.

This refers to the variety of species. It relates to the number of species in a defined area.

The diversity of species can be measured through its richness, abundance, and types.

some areas are more rich in species than others.

Areas rich in species diversity are called hotspots of diversity.

Species is a fundamental unit of classification and is described as the largest group of organisms in which two individuals can mate and produce fertile offspring, typically by sexual reproduction, and thus, share a common ancestry. The numbers of species of flora and fauna that are present in an area comprise its species diversity.

This diversity is seen both in the natural ecosystems and agricultural ecosystems. Some areas are richer in species than others. Every ecosystem contains a unique set of species, all interacting
with each other while some ecosystems could have more numerous species than another

Importance of Biodiversity

1. An integral part of Cultural Identity.

2. Used for medicinal Purposes.

3. Contribute to climate stability.

4. Provide more food resources.

5. Relation b/w Biodiversity and Industry.

6. Economic benefits of biodiversity

7. Helps in pollution management

8. Forming a healthy ecosystem

9. Acts as a source of recreation

10. Soil quality improvement

Factors Influencing Biodiversity

Biodiversity varies from place to place. Factors that affect biodiversity in an ecosystem include area, climate, and diversity (variety) of niches.


Within an ecosystem, a large area will contain more species than a small area.

For example,

Suppose you are counting tree species in a forest. You would find far more tree species in a 100 sq meter area than in a 10 sq meter area.


In general, the number of species increases from the poles towards the equator. Climate change is generally more gradual than habitat destruction, but it threatens ecosystem biodiversity because climate strongly influences the kinds of organisms that have adapted to each ecosystem.

Niche Diversity

Coral reefs make up less than 1% of the Earth’s oceans but are home to about 20% of the world’s saltwater fish species.

A reef (like a rainforest supports many different niches for organisms that live there.

This enables more species to live in a reef than in a more uniform habitat, such as a flat sandbar.
Factors that Increase BiodiversityFactors that Decrease Biodiversity
1. Physically diverse habitat1. Environmental stress
2. Moderate environmental disturbance2. Large environmental disturbance
3. Small variation in environmental conditions 3. Extreme environmental conditions
4. Middle stages of succession 4. Severe limitations of an essential resource
5. Evolution5. Geographic isolation

Factors Contributing To Biodiversity

There are three main factors that can affect biodiversity. They are a change in habitat, a change in the climate, and a decrease or influx of any one species. These factors can be affected naturally, or by human influence. For example, a disease may affect one particular species in an ecosystem and throw off the balance in that area. If all the wolves in the system get sick and many die off, there will be an increase in the rabbit population, which will then mean certain vegetation will be decimated. A change in climate can affect the growth of plants, increasing some or decreasing the likelihood of survival for others. It similarly can cause harm to animals in that system.

A Biodiversity Hotspot

Conservation International, CC BY-SA 4.0 <;, via Wikimedia Commons

A biodiversity hotspot is any area that is both highly diverse and rich in organic life, but also at risk due to human activity. Usually, these are areas that have high biodiversity but are being destroyed for human habitation or development.

Measurement Of Biodiversity

Biodiversity is generally measured in terms of density or richness. This is calculated by accounting for the number of each species within a given area. By analyzing how many individuals of that species exist in a certain region, you can determine how dense that population is. This is also used in relation to a species’ evenness, ie how close in numbers each species is to each other. Evenness is the technical way to measure whether or not a system is ‘in balance’ by comparing the evenness of various species in a particular ecosystem. Biodiversity can also be measured on a genetic level.

Biome With Highest Biodiversity

Tropical forests are known to be the most highly diverse biome on the planet. Rainforests have the greatest species diversity throughout various continents, with most containing a wide variety of plant, animal, and insect life. Species diversity tends to be higher in warmer climates, whereas cold climates generally have a low diversity level.

Loss of Biodiversity

Tropical regions which occupy only about one-fourth of the world, contain about three-fourth of the world’s human population.

Overexploitation of resources and deforestation have become rampant to fulfill the needs of large populations.

As these tropical rain forests contain 50 percent of the species on the earth, the destruction of natural habitats has proved disastrous for the entire biosphere.

Factors responsible for loss of biodiversity

Natural calamities such as earthquakes, floods, volcanic eruptions, forest fires, droughts, etc. cause damage to the flora and fauna of the earth, bringing changes to the biodiversity of respective affected regions.

Pesticides and other pollutants such as hydrocarbons and toxic heavy metals destroy the weak and sensitive species.

A natural biotic community of the ecosystem suffered extensive damage because of the introduction of exotic species. The species that are not the natural inhabitants of the local habitat but are introduced into the system are called exotic species.

The international Union of Conservation of Nature and Natural Resources (IUCN) has classified the threatened species of plants and animals into three categories for the purpose of their conservation.

Endangered Species

Vulnerable Species

Rare Species

Endangered Species

It includes those species which are in danger of extinction.

The IUCN publishes information about endangered species world-wide on the Red List of threatened species.

Vulnerable Species

This includes the species which are likely to be in danger of extinction in the near future if the factors threatening their extinction continue.

Survival of these species is not assured as their population has reduced greatly.

Rare Species

Population of these species is very small in the world.

They are confined to limited areas or thinly scattered over a wider area.

poachers drive
Black-and-white ruffed lemur

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