Biological Diversity or Biodiversity

  • The term biological diversity (or Biodiversity) was coined by Walter G. Rosen in 1986.
  • The term biodiversity includes diversity within species, between species and of ecosystems.

Types of Species Diversity:

Genetic Diversity:

  • Genes give specific characteristics to individual.
  • Each member of any animal or plant species differs  from other individuals in its genetic material because of the large number of possible combinations in the genes.
  • Due to this genetic variability healthy breeding population of a species is assured.
  • The diversity in wild species forms the ‘gene pool’ from which our crops and domestic animals have been developed over thousands of years. Using this gene pool new varieties of more productive and diseases resistant crops is obtained. Similarly breed of better domestic animals is obtained.
  • In modern biotechnology  and genetic engineering techniques genes are manipulated for developing better types of medicines and a variety of industrial products.

Species Diversity:

  • The numbers of species of plants and animals that are present in a region constitutes its species diversity. This diversity can be observed in  both in natural ecosystems and in agricultural ecosystems.
  • Natural tropical forests have much greater species richness than plantations.
  • A natural forest ecosystem provides fruit, fuel wood, fodder, fiber, gum, resin and medicines to local people.
  • Areas that are rich in species diversity are called ‘hot spots’ of diversity.

Ecosystem or Community Diversity:

  • There are a large variety of different ecosystems on earth,Ecosystem diversity can be described for a specific geographical region.
  • Distinctive land ecosystems include landscapes such as forests, grasslands, deserts, mountains, etc. Aquatic ecosystems includes rivers, lakes, and the sea.
  • Due to overuse or misuse productivity of ecosystem is decreases and the ecosystem becomes degraded.

Types of Ecosystem Community Diversity:

  • R.H. Whittaker proposed four level of diversity.

Point Diversity:

  • This is the diversity on a smallest scale. It is diversity in microhabitat.

Alpha Diversity:

  •  It is diversity over comparatively larger area. It is also called local diversity.
  • It includes variety of living organisms occurring in a particular habitat.It is usually expressed by the number of species in that ecosystem.
  • This is measured by counting the number of taxa (distinct groups of organisms) within the ecosystem

Gamma Diversity:

  • It is diversity over larger area or region such as island or landscape. It is a measure of the overall diversity for the different ecosystems (alpha diversity) within a region.
  • It is the inclusive diversity of all the habitat types within an area (region).

Epsilon Diversity:

  • The epsilon or regional diversity is defined as the total diversity of a group of areas of gamma diversity.


  • A single plant can be considered as example of unit of alpha diversity, then leaf of a plant can be considered as point diversity.  The group of plants together in region can be considered as gamma diversity. The forest in which this region is located can be considered as epsilon diversity.

Mathematical Approach Towards Diversity:

Beta Diversity:

  • R.H. Whittaker defined it as “the extent of change in community composition, or degree of community differentiation, in relation to a complex-gradient of environment, or a pattern of environments”.
  • Beta diversity is defined as the ratio between gamma (regional) and alpha (local) diversities .
  • Beta diversity does not only account for the relationship between local and regional diversity, but also informs about the degree of differentiation among biological communities.
  • It is a bridge from the alpha (local) diversity to the gamma (regional) diversity.

Delta Diversity:

  • Delta diversity is defined as the change in species composition and abundance between areas of gamma diversity, which occur within an area of epsilon diversity.
  • It shows differentiation diversity over wide geographic areas.

Region of Megadiversity:

  • The warm and humid tropical regions of the earth between the tropic of Cancer and tropic of Capricorn, are rich in diversity of life i.e. plants, animals and microorganisms. This region is called region of megadiversity.
  • More than half of the biodiversities of the world are concentrated in 12 countries. They are Brazil, Colombia, Ecuador, Peru, Mexico, Zaire, Madagascar, Australia, China, India, Indonesia and Malaysia.

Uniqueness of Indian Biodiversity:

  • India is one of the 12 megadiversity countries in the world.
  • India is divided into 10 biogeographical regions.
  • India has variety of physical features and climatic conditions. India has forests, grasslands. deserts, rivers, wetlands, coastal and marine regions which act as ecosystem and habitat for variety of animals.Hence India has a great biodiversity .

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