[Biology] Bio-diversity

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  • The term Biodiversity comes from two words: ‘bio’ meaning life and ‘diversity’ means variability.
  • Biodiversity represents variety in all the living beings i.e. the different plants, animals, microorganisms along with all the genetic information they have and the ecosystem they form.


  • Biodiversity describes the enormous variety of life on earth.
  • It is estimated that there are about 8.7 million species of animals and plants in existence, of which only 1.2 million species have been identified.
  • Most of the organisms remain a complete mystery. There is so much biodiversity to be discovered.
  • All of the species that are currently alive today have evolved unique traits, over generations, that make them distinct from other species. Organisms with the same ancestral history have evolved to an extent where they can no longer reproduce with each other and are considered different species.


  • Biodiversity is usually explored at three levels, which work together and create complexity of life on earth.
  • These include:
    • Genetic diversity
    • Species diversity
    • Ecosystem diversity


  • Genetic diversity refers to the variety of genes within a species.
  • it encompasses the variety in type and number of genes and chromosomes present in various species.
  • Every individual of a species has its own genetic composition. It means that a species may have different populations, each with different genetic combinations.


  • Various breeds of dogs, as they are bred to get the desired traits.
  • Varieties of rose, wheat, woody plants etc.
  • There are more than 50,000 varieties of rice in India.


  • The variation of different genes allows the individual or the whole population to have the ability to bear any form of environmental stress.
  • The ones able to bear and adapt to change have a greater chance of survival than those who fail to do so. Thus, genetic diversity can, in a way, tackle natural selection to give a better environment.
  • Genetic diversity helps to grow new varieties of plants with better and desirable traits.
  • It also reduces the recurrence of undesirable traits.


  • Species diversity is defined as the number of species per unit area. It refers to the variety of species in a habitat and their relative abundance.
  • The species diversity varies with geographical location as tropics are richer in species and it declines as we move towards the poles.

  • Species diversity has two constituents:


  • Species richness refers to the number of various species present in an ecosystem.
  • Tropical areas have greater species richness.


  • the relative abundance of individuals in each of the species.
  • A species is said to have high evenness when the number of its individuals is fairly constant across the communities.


  • More diverse ecosystem tends to be more productive as a larger number of producer species will produce a larger biomass for consumer species.
  • Greater productivity makes the ecosystem more stable.
  • Rich diversity is necessary for the survival of organisms as it increases the ability to withstand catastrophes like drought, infestations etc.
  • Humans also derive various products from nature i.e. fruits, meat, medicine, wood antibiotics, dyes as a result of species diversity.
  • Besides these, there are other benefits as recreation, tourism, education and research etc.


  • Ecological diversity explains the interaction and aggregation of species living together and the physical environment of that region. Ecological diversity refers to biotic communities, habitats and ecological processes occurring in the entire biosphere.
  • Ecosystem diversity deals with;
  1. Variations in ecosystems within a geographical location and its impact on the existence of mankind and the environment.
  2. Variations in the complexity of a community, including the number of different niches, trophic levels and other ecological processes.
  3. Variations in the plant and animal species that live together and are connected by food chains and food webs.
  • It is the largest scale of biodiversity, and within each ecosystem, there is both species and genetic diversity.


  • The landscapes i.e. mountains, grasslands, deserts exhibit ecosystem diversity.



  • Biodiversity on earth is not uniform, rather distributed unevenly, in which latitude gradient pattern can be observed.
  • Latitudinal diversity is an increase in the number of species from high to low latitudes.
  • This means that tropics or the warm productive regions of the globe host a greater variety of species.
  • This number decreases as we move towards the poles.


  • Within America, measures of local mammal diversity vary from 178 species in tropical regions of the southern part of central America to only 20 species in arctic regions of north-central Canada.


  • The species-area relationship is the oldest known and most documented pattern in ecology.
  • It describes the general pattern of increasing richness of species with the increase in area of observation.


  • A species-area curve is a relationship between the area (taken on x-axis) and the number of species (taken on y-axis) found within that area. Larger areas tend to contain larger numbers of species.

  • It is important to note that on log scale, the species-area relationship becomes linear and is represented by the following equation;


The maintenance of biodiversity is very necessary for sustaining life on earth. Some of the reasons why biodiversity is important are:


  • Every species has its specific role in an ecosystem.
  • They take over and store energy and also produce and decompose the organic matter.
  • The ecosystem sustains the services without which humans cannot survive. A diverse ecosystem is more productive and is able to withstand environmental stress.


  • Biodiversity serves as a reservoir of resources for the manufacture of food, cosmetics and pharmaceuticals.
  • Plants, livestock, fishery, and forests etc. are the rich sources of food.
  • Wild plants such as Cinchona are used for medicinal purposes.
  • Wood, fiber, perfumes, lubricants, rubber, resins and cork are all derived from different plants.
  • The national parks and sanctuaries provide a source of recreation and tourism. They are a source of beauty and joy for people.


  • Biodiversity plays an important role in prevention of extinction of species.
  • Biodiversity enables species to adapt according to the environment, thereby not only ensuring their preservation but also providing a vast genetic pool.
  • Biodiversity is also responsible for the provision of food and wide range of material for survival.


  • Biodiversity gives stability to the ecosystem and maintains the ecological balance. Different species in the ecosystem are linked to each other through food chains and food webs. The loss of one species affects the survival of other species. Thus, the ecosystem becomes fragile.
  • Biodiversity plays an important role in soil formation and its conservation. Vegetation improves the soil structure; water holds the capacity of the soil and raises the nutrient level of the soil.
  • Biodiversity also plays a part in nutrient recycling. It serves as the sink and source of nutrients. Microorganisms decompose the dead plants and animals in the soil thus facilitate the return of nutrients to the soil.
  • Forests with diverse groups of plant species are the major sinks of carbon dioxide which is a greenhouse gas causing global warming, thus biologically diverse forests help in reducing global warming.
  • Biodiversity protects the water resources. Vegetation facilitates the percolation of water into the soil, thus helping in maintenance of the ground water table.


  • The major threat to biodiversity, according to Edward Wilson, is HIPPO.
  • HIPPO stands for;
    • Habitat destruction
    • Climate change
    • Invasive species
    • Pollution
    • Human overpopulation
    • Over-harvesting


  • Habitat loss refers to changes in the ecosystem that results in the development of a non-viable habitat.
  • Such a habitat can no longer support the organisms present, thus leading to a decline in their population.


  • It is the long term and irreversible change that occurs in the Earth’s climate.
  • The increase in the temperature of the atmosphere has some major effects on our environment such as the seasons, rising sea levels, and glacial retreats.
  • The rapidly increasing rate of climate change is a great threat for human security as it is exacerbating the problem of habitat loss and natural resources are becoming more and more limited.


  • All forms of pollution are a threat to all life forms on Earth. However, it imposes a major threat to biodiversity when it comes to the nutrient reloading of the elements; nitrogen and phosphorus.


  • Overexploitation means overharvesting species at rates faster than they can sustain themselves in the wild. Because of this, the species population is put into risk of extinction.


  • With the rapid increase in human population, natural habitats are being lost and human indulgence in bio-diversity is increasing.
  • The human-induced activities such as economic, technological, scientific, cultural, and demographic factors also have great impact on biodiversity.


  • Invasive Species (alien species), are non-native species, having arrived and settled outside their natural distribution to areas where they easily invade ecosystems, marginalize and deteriorate several native species which brings about large scale environmental, ecological, and economic damage.
  • Loss of habitat is in-turn exacerbating the problem of invasive species which aid in loss of biodiversity.


Conservation of biodiversity refers to the protection, restoration and management of biodiversity to derive sustainable benefits for present and future generations.


  • Biodiversity can be conserved by reversing the decline of species. The aim of this is to restore the population of declined species.
  • The conservation of all biological aspects covers and conserves food, livestock, microbes, agriculture including plants and animals.
  • Biodiversity can be conserved by effective utilization of natural resources.
  • Deforestation can be preserved by every means.
  • Poaching and killing wild animals must be prohibited.
  • Public awareness must be provided about biodiversity and its conservation.


  • Arihant’s handbook of biology. The living world. Page no: 1-6.
  • NCERT biology; textbook for class 11. The living world. Page no: 1-62.
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