Chapter 18: Biodiversity, Classification and Conservation


Biodiversity is the variety of life on Earth at all its levels, from genes to ecosystems, and can encompass the evolutionary, ecological, and cultural processes that sustain life. Biodiversity is usually explored at three levels – genetic diversity, species diversity and ecosystem diversity. These three levels work together to create the complexity of life on Earth.

Genetic Diversity refers to the range of different inherited traits within a species. In a species with high genetic diversity, there would be many individuals with a wide variety of different traits. Genetic diversity is critical for a population to adapt to changing environments. Different breeds of dogs. Dogs are selectively bred to get the desired traits. Different varieties of rose flower, wheat, etc. There are more than 50,000 varieties of rice and more than a thousand varieties of mangoes found in India.

Species diversity is defined as the number of species and abundance of each species that live in a particular location. The number of species that live in a certain location is called species richness. Australia’s Great Barrier Reef is an example of species diversity. It is the home to the largest coral reef in the world. It contains approximately 400 different types of coral species, 150 fish species, 4000 species of mollusks, and 10 species of turtles.

Ecosystem diversity deals with the variations in ecosystems within a geographical location and its overall impact on human existence and the environment. Ecosystem diversity addresses the combined characteristics of biotic properties (biodiversity) and abiotic properties (geodiversity). Some examples are Deserts, Forests, Rainforests, etc.

Biodiversity can also be measured using the index of diversity (D) which can be calculated as following:

D= Diversity index

N= total number of organisms

n= total number of organisms of each species


Pearson’s Correlation

Pearson’s correlation coefficient is the test statistics that measures the statistical relationship, or association, between two continuous variables. … It gives information about the magnitude of the association, or correlation, as well as the direction of the relationship.

To calculate the Pearson product-moment correlation, one must first determine the covariance of the two variables in question. Next, one must calculate each variable’s standard deviation. The correlation coefficient is determined by dividing the covariance by the product of the two variables’ standard deviations.


Spearman’s Rank-order Correlation

The Spearman’s rank-order correlation is the nonparametric version of the Pearson product-moment correlation. Spearman’s correlation coefficient, (ρ, also signified by rs) measures the strength and direction of association between two ranked variables.


Classification is the process of naming and organizing organisms into groups based on their characteristics. Organisms can be grouped into one of the five kingdoms: animals, plants, fungi, prokaryotes and protoctista.

  1. Animals
  • Multicellular
  • Presence of a nucleus and other membrane bound organelles
  • No cell wall
  • No chloroplasts
  • They store food in the form of glycogen
  1. Plants
  • Multicellular
  • Presence of a nucleus and other membrane bound organelles
  • Contains a cellulose cell wall
  • Contain chloroplasts as well as chlorophyll
  • Store food in the form of starch
  1. Protoctista
  • Mostly unicellular
  • Presence of a nucleus and other membrane bound organelles
  • Some contain chloroplasts
  • Some can he heterotrophic feeders
  • Some can be parasite
  • Some can be both autotrophic and heterotrophic
  1. Fungi
  • They can be multicellular or unicellular
  • Contain chitin cell wall
  • Presence of nucleus and other membrane bound organelles
  • Contain no chloroplasts or chlorophyll
  • Most of them have body or mycelium composed of thread like hyphae
  • Mostly store food in the form of glycogen
  1. Prokaryotes
  • Mostly unicellular
  • Divided into two domain; Bacteria and Archaea
  • Lack an envelope enclosed nucleus, mitochondria or any other eukaryotic membrane bound organelles
  • They can store food in the form of lipid molecules or glycogen granules.


Extinction is when a species come to an end or dies out. Extinction occurs when species are diminished because of environmental forces (habitat fragmentation, global change, natural disaster, overexploitation of species for human use) or because of evolutionary changes in their members (genetic inbreeding, poor reproduction, decline in population numbers). Humans also cause other species to become extinct by hunting, overharvesting, introducing invasive species to the wild, polluting, and changing wetlands and forests to croplands and urban areas.

Mass extinction events have also occurred in the past where a very large number of species went extinct at one time. The rate of extinction during these periods is very high.

Past mass extinctions were likely caused by major and sudden shifts in the environment such as an Ice Age or an asteroid hitting the earth.

The reasons for extinction include following:

  • Climate change
  • Competition
  • Introduction of species
  • Hunting by Humans
  • Degradation and loss of habitats


There are many threats to the endangered species in the ecosystem. They may go extinct any time. By conserving wildlife, we’re ensuring that future generations can enjoy our natural world and the incredible species that live within it. To help protect wildlife, it’s important to understand how species interact within their ecosystems, and how they’re affected by environmental and human influences.

  • National parks and marine parks are examples of conservation methods that do this

Conservation means using natural resources wisely, while preservation simply allows game species to go to waste and reduces opportunities to increase the populations of other species.

  • Zoos and botanic gardens take part in conservation programs

Conserved areas

  • National parks are areas within countries where the wildlife and environment are protected
  • Governments control these areas and pass legislation to ensure their protection
  • There are several restrictions

Human’s access is strictly controlled

Industrial activities such as agriculture and building are tightly regulated

Hunting is limited or completely prohibited

  • Marine parks are protected areas of water that have been set up for the conservation of endangered marine ecosystems and species
  • They also have restrictions to prevent overfishing and pollution
  • Public engagement with conservation efforts is important for long term success:
  • Zoos can also contribute towards the conservation of endangered animal species
  • Botanic gardens are the plant equivalent of zoos

Non-governmental organizations, such as World Wide Fund for Nature (WWF) and Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) play important role in local and global conservation.