MEVE 014: Unit 01 - Concept of Biodiversity

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 UNIT 1: CONCEPT OF BIODIVERSITY

1.0 Introduction

Biodiversity, a contraction of "biological diversity," refers to the variety and variability of life on Earth. It encompasses the different organisms, ecosystems, and genetic differences within species. As the foundation of ecosystem services essential for human survival, biodiversity is crucial for food security, climate regulation, medicine, and cultural identity. Understanding its composition, measurement, and conservation is essential in an era of environmental change and biodiversity loss.

1.1 Objectives

After studying this unit, you will be able to:

  • Define and explain the concept and scope of biodiversity.
  • Distinguish between different types and levels of biodiversity.
  • Understand the constraints and challenges in biodiversity science.
  • Apply different measures and indices of biodiversity.
  • Evaluate the ecological significance and value of biodiversity.

1.2 Concept and Definition

  • Biodiversity is the total variability of life forms on Earth, from genes to ecosystems.
  • Defined by the UN Convention on Biological Diversity (CBD, 1992) as:

“The variability among living organisms from all sources, including terrestrial, marine, and other aquatic ecosystems, and the ecological complexes of which they are part; this includes diversity within species, between species, and of ecosystems.”

  • It is a multi-dimensional concept, incorporating:
    • Genetic diversity within species
    • Species diversity among organisms
    • Ecosystem diversity across landscapes

1.3 Scope and Constraints of Biodiversity Science

Scope:

  • Encompasses research in taxonomy, ecology, genetics, conservation biology, and climate science.
  • Supports ecosystem services like pollination, water purification, disease regulation, and nutrient cycling.
  • Aids sustainable agriculture, forestry, and medicine through gene and species conservation.

Constraints:

  • Incomplete taxonomic knowledge (only a fraction of species are described).
  • Limited funding and political will for biodiversity studies.
  • Data gaps in poorly studied habitats like deep oceans or tropical forests.
  • Rapid loss of biodiversity due to anthropogenic pressures outpacing conservation efforts.

1.4 Composition and Types of Biodiversity

Biodiversity is structured into four key components:

1.4.1 Genetic Diversity

  • Refers to the variation of genes within a species.
  • Enables populations to adapt to environmental changes and resist diseases.
  • Example: Diverse rice varieties in India adapted to different soil and climate conditions.

1.4.2 Species/Organismal Diversity

  • Diversity of species in a particular region.
  • Includes species richness (number of species) and species evenness (abundance distribution).
  • Example: Coral reefs exhibit high species diversity.

1.4.3 Ecological/Ecosystem Diversity

  • Variety of ecosystems in a geographical location.
  • Includes terrestrial (forests, deserts), freshwater (lakes, rivers), and marine ecosystems (estuaries, coral reefs).
  • Example: India hosts ecosystems ranging from Himalayas to mangroves.

1.4.4 Landscape/Pattern Diversity

  • Diversity of habitat types, landforms, and spatial arrangements in a region.
  • Influences species distribution and ecological interactions.
  • Example: The Western Ghats’ mosaic of forests, grasslands, and agricultural fields.

1.5 Measures of Biodiversity

Quantifying biodiversity helps in comparing ecosystems and guiding conservation priorities.

1.5.1 Indices of Biodiversity and Evenness

  • Species Richness: Number of species in a sample.
  • Shannon-Wiener Index (H′): Considers both richness and evenness.
  • Simpson's Index (D): Probability of two individuals belonging to the same species.
  • Evenness Index (E): Distribution of individuals among species.

These indices help in monitoring biodiversity loss or restoration effectiveness.

1.5.2 Alpha, Beta, and Gamma Diversities

  • Alpha Diversity: Diversity within a specific habitat or ecosystem.
    • Example: Number of tree species in a forest patch.
  • Beta Diversity: Difference in species composition between ecosystems.
    • Example: Comparing species between a grassland and adjacent forest.
  • Gamma Diversity: Total diversity across a large geographic region or landscape.
    • Example: Biodiversity of an entire river basin or mountain range.

1.6 Let Us Sum Up

  • Biodiversity includes genetic, species, ecosystem, and landscape diversity.
  • It plays a critical role in ecological stability, resilience, and human well-being.
  • Measurement of biodiversity through various indices and diversity types provides a scientific basis for conservation strategies.
  • Despite its importance, biodiversity science faces multiple challenges, including data limitations, human-induced threats, and funding issues.

1.7 Key Words

  1. Biodiversity – The variety of life at all levels, from genes to ecosystems.
  2. Genetic Diversity – Variation of genes within species.
  3. Species Diversity – Variety and abundance of species in a region.
  4. Ecosystem Diversity – Variety of habitats and ecological processes.
  5. Landscape Diversity – Spatial variation in landforms and habitats.
  6. Species Richness – Number of species in a defined area.
  7. Evenness – Uniformity in species abundance.
  8. Shannon-Wiener Index – A measure of species diversity accounting for richness and evenness.
  9. Alpha Diversity – Diversity within a habitat or ecosystem.
  10. Beta Diversity – Species turnover between habitats.
  11. Gamma Diversity – Overall diversity across regions or landscapes.

 

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