Study Notes on Biodiversity For UGC NET Paper-1

By Mohit Choudhary|Updated : October 1st, 2022

 UGC NET EXAM consists of paper 1 and paper 2. The environment section is the most important part of Paper-1. Every year 5 questions are asked directly from it. Anyone aiming to clear NET/ NET-JRF cannot ignore this section. A holistic preparation of Paper-1 can help you clear the Exam in one go. Don’t forget to do mock tests as well. It helps you identify your weak areas so that improvement could be made there. In today’s post, we are providing study notes on Biodiversity. Keep learning and working hard.

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What is Biodiversity?

  • Biodiversity term is giver by E.D Wilson.
  • It is defined as ‘the variability among living organisms from all sources, including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part; this includes diversity within species, between species and of ecosystems’.
  • Robert May estimated that there are around 7 million species globally, out of which more than 75 percent are yet to be discovered.

Levels of Biodiversity

Genetic diversity

  • It is the total number of genetic characteristics in the genetic makeup of a species.
  • Genetic diversity allows species to adapt to changing environments, survive drastic changes and thus carry on desirable genes.
  • Woody plants, such as trees, tend to have more genetic diversity, on the whole, than vascular plants, such as grasses.
  • Diversity occurs due to the size of each species geographic range.
  • The genetic diversity gives us beautiful butterflies, roses, parakeets or coral in a myriad hues, shapes and sizes.

Species diversity

  • It is defined as number of different species present in an ecosystem and relative abundance of each of those species.
  • Species differ from one another, markedly in their genetic makeup, do not inter-breed in nature.
  • Closely-related species however have in common much of their hereditary characteristics. For instance, about 98.4 per cent of the genes of humans and chimpanzees are the same.
  • The species diversity varies in a different geographical location with tropics having different geographical location with tropics having highest and declines as we move towards poles.
  • Examples- four or five different species of tree in a woodland forest, more than hundred varieties of fishes, crustaceans and coral in a certain reef.

Community diversity

  • This refers to variations in biological communities in which species live.
  • It represents the diversity of organism sharing the same habitat or community.
  • In a habitat this is clearly visible. A habitat comprises of climate, vegetation and geography of a region.
  • There are several kinds of habitats present around the world.
  • Example of habitats- Corals, grasslands, wetland, desert, mangrove and tropical rain forests.
  • Species adapt to different kind of climatic conditions. Therefore, the variety or diversity of species in the ecosystem is influenced by the nature of ecosystem.

Measurement of Biodiversity

Biodiversity is measured by two different ways:

1. Species richness

2. Species evenness.

Species richness

It refers to the number of different species present in an area. More species means greater richness.

1. Alpha diversity

It is diversity within a particular area or ecosystem and is expressed by the number of species in that ecosystem.

2. Beta diversity

It compares diversity between ecosystems and is expressed as the change in amount of species between the ecosystems.

3. Gamma diversity

It is a measure of the overall diversity for the different ecosystems within a region.

Species evenness

  • IT refers to how close in numbers each species in an environment is.
  • It describes the relative abundance of the different species in an area.
  • Low evenness indicates that a few species dominate the site, more abundance means more evenness.

Biodiversity and Food Web

  • Biodiversity refers to the web of life as many microorganism, plant and animals interact with each other.
  • Food web refers to who eats whom in a habitat.
  • Plant, animals and humans building block of life are four elements- carbon, oxygen, nitrogen and hydrogen.
  • These are present in air, water and soil
  • Green plants are called producers because they use Nitrogen, sunlight and water to produce energy by a process called Photosynthesis.
  • Animals and Humans are called consumers because they consume plants are their food.
  • The chain that links consumers to producers is called the food chain or web.
  • Every living creature is found in a food chain.
  • There are several food chains and they can be complex or simple depending on the environment.
  • For examples, grasshoppers eat grass and are in turn eaten by frogs; snakes eat frogs and rodents.
  • Tampering with the food chain only produces negative results, leading to the destruction of the species.
  • Each time a species become extinct, it leads to breaking of chain and threat for human survival.

Services provided by Biodiversity

Ecosystem services

  • Supporting soil formation
  • Supporting nutrient cycling.
  • Supporting primary production.
  • Regulating climate.
  • Water purification.
  • Pollination
  • Protection of water resources
  • Pollution breakdown and absorption
  • Maintenance of ecosystems
  • Recovery from unpredictable events

Biological services

  • Fresh Water.
  • Food
  • Fuelwood
  • Fiber
  • Genetic resources
  • Ornamental plants
  • Breeding stocks
  • Medicinal resources and pharmaceutical drugs.

Social services

  • Spiritual and religious.
  • Recreation and ecotourism.
  • Aesthetic and inspirational.
  • Sense of pride.
  • Research, education and monitoring
  • Cultural heritage.

Causes for Biodiversity Loss

  • It is termed as decrease in biodiversity within a species, an ecosystem and a given geographic area.
  • It is defined in terms of loss of a particular species or the habitat essential for its survival.
  • Leading cause of extinction of species is for economic gain or for hunting for food.
  • Climate change is another reason for extinction of species that man is hugely responsible for.

Natural causes

  • floods,
  • earthquakes,
  • landslides,
  • rivalry among species,
  • lack of pollination and diseases.

Man-Made causes

  • Habitat destruction
  • Uncontrolled commercial exploitation
  • Hunting & poaching
  • Conversion of rich biodiversity site for human settlement and industrial development
  • Extension of agriculture
  • Pollution
  • Filling up of wetlands
  • Destruction of coastal areas

Biodiversity conservation

Ex-situ conservation

  • Conservation of biodiversity or reintroduction of animals or plants outside an area where they naturally occur.
  • Example- Zoological parks or Botanical gardens and Reintroduction of various species in different national parks. Also seed banks and horticultural and recreation garden.

In-situ conservation

  • Conserving biodiversity and animals or plants in their own natural habitats is known as in-situ conservation.
  • Example-National parks, Sanctuaries, Biosphere reserves, Reserved forests, Protected forests.

We hope you all understood the terms related to biodiversity.

Thank you,

Team BYJU'S Exam Prep


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