1. What is Biodiversity?
Definition:
Biodiversity is the term used to describe the variety of life forms on Earth. It includes the diversity of:
- Genes (within species)
- Species (number and types of organisms)
- Ecosystems (natural habitats and interactions)
The term was coined from “biological diversity” and refers not just to the number of species, but also to the genetic variation within them and the ecosystems they form.
2. Levels or Types of Biodiversity:
a. Genetic Diversity:
- Refers to the variation in genes within a species.
- Every individual in a species is genetically different from the other.
- More genetic variation means better adaptability to environmental changes.
Example:
- Different varieties of rice (e.g., Basmati, IR-64).
- Different breeds of dogs (Labrador, German Shepherd, Pug).
b. Species Diversity:
- Refers to the variety of species present in a particular region or ecosystem.
- It considers both the number of species (richness) and their relative abundance.
Example:
- The Western Ghats have over 7,400 plant species.
- Coral reefs have high fish species diversity.
c. Ecosystem Diversity:
- Refers to the variety of ecosystems in a given area.
- Each ecosystem has its own climate, soil, flora, fauna, and interactions.
Example:
- Deserts (like Thar), rainforests (like in Assam), wetlands (like Chilika Lake), and alpine ecosystems (like the Himalayas).
3. Significance of Biodiversity:
Biodiversity is crucial for the survival and well-being of life on Earth.
i. Ecological Role:
- Each species plays a role in maintaining the balance of nature.
- Pollination by bees, oxygen production by plants, decomposition by fungi—are all essential services provided by biodiversity.
ii. Economic Importance:
- Provides resources such as food, medicines, timber, fiber, and industrial materials.
- Biodiverse ecosystems support agriculture, fisheries, and tourism industries.
Example:
- Neem and turmeric are medicinal plants.
- Forests provide timber, gum, and resins.
iii. Scientific and Educational Value:
- Biodiversity helps scientists understand evolution, genetics, and ecological interactions.
- It offers opportunities for research and learning.
iv. Cultural and Aesthetic Value:
- Many species are considered sacred or important in traditions.
- Natural landscapes and wildlife attract tourism and artistic inspiration.
4. Levels of Measuring Biodiversity (as per ICSE Syllabus):
a. Alpha Diversity:
- Refers to species diversity within a specific area or ecosystem.
- Example: Number of species in a pond.
b. Beta Diversity:
- Refers to the difference in species between two habitats.
- It indicates species turnover or change in biodiversity.
- Example: Comparison of a pond and a nearby forest.
c. Gamma Diversity:
- Refers to the overall biodiversity across larger landscapes or regions.
- Example: Total biodiversity of the Western Ghats region.
5. Conservation of Biodiversity:
To protect biodiversity, two main conservation methods are followed:
a. In-situ Conservation:
- Protecting the species in their natural habitat.
- Maintains not only species but also their interactions with the environment.
Examples:
- National Parks (e.g., Jim Corbett National Park)
- Wildlife Sanctuaries (e.g., Kaziranga Sanctuary)
- Biosphere Reserves (e.g., Nilgiri Biosphere Reserve)
b. Ex-situ Conservation:
- Conserving organisms outside their natural habitats.
- Useful for endangered species that cannot survive in the wild.
Examples:
- Zoological Parks
- Botanical Gardens
- Seed Banks
- Gene Banks
6. Threats to Biodiversity:
Biodiversity is under serious threat due to human activities. Some of the major threats include:
- Habitat destruction: Due to deforestation, urbanization, and mining.
- Pollution: Air, water, and soil pollution affect both flora and fauna.
- Overexploitation: Excessive hunting, fishing, and logging.
- Climate change: Global warming alters habitats and species survival.
- Invasive species: Non-native species often compete with or kill local species.
- Illegal wildlife trade: Poaching of tigers, elephants, and rare plants.
7. Biodiversity Hotspots:
Definition:
A biodiversity hotspot is a region that is rich in endemic species but is also highly threatened due to human activities.
To qualify as a hotspot:
- Must have at least 1,500 endemic vascular plant species.
- Must have lost at least 70% of its original vegetation.
Examples of Biodiversity Hotspots in India:
- The Himalayas
- Western Ghats
- Indo-Burma region
- Sundaland (including Nicobar Islands)
8. Important Terms (ICSE Format):
| Term | Definition |
|---|---|
| Endemic Species | Species found only in a particular region and nowhere else. |
| Extinct Species | Species that no longer exist anywhere on Earth. |
| Endangered Species | Species that are at high risk of extinction in the near future. |
| Exotic/Invasive Species | Species introduced to a region where they are not native, often harmful. |
| Conservation | Planned management to preserve biodiversity and natural resources. |
9. Sample ICSE Board-style Questions:
Q1. Define biodiversity. Explain its three types with suitable examples.
Q2. What is ecosystem diversity? How is it different from species diversity?
Q3. What are the differences between in-situ and ex-situ conservation? Give two examples of each.
Q4. Define biodiversity hotspot. Name any two such hotspots found in India.
Q5. List four major threats to biodiversity.