Biodiversity Patterns and Conservation

Biodiversity Patterns and Conservation

Biodiversity (जैव विविधता) refers to the variety and variability of living organisms present on Earth. It includes diversity at the level of genes, species and ecosystems.

Biodiversity is not uniformly distributed across the Earth. Different regions have different numbers and types of species. Some regions are exceptionally rich in species and are called biodiversity hotspots.

1. Levels of Biodiversity

Biodiversity can be studied at three major levels:

Level	Meaning	Example
Genetic diversity	Variation in genes within a species	Different varieties of rice
Species diversity	Variety of species in a region	Different species of birds, mammals and plants
Ecosystem diversity	Variety of ecosystems in a region	Forests, grasslands, deserts, wetlands

2. Patterns of Biodiversity

Biodiversity shows certain geographical patterns. Two important patterns are:

• Latitudinal gradient
• Species-area relationship

3. Latitudinal Gradient

The latitudinal gradient refers to the gradual change in species diversity with latitude.

In general, species diversity is highest near the equator and decreases as we move towards the poles.

Tropics → Higher Species Diversity

Temperate Regions → Lower Species Diversity

Polar Regions → Still Lower Species Diversity

This pattern is clearly observed in many groups of organisms.

Why are Tropical Regions More Biodiverse?

Several explanations have been proposed:

• Tropical regions have remained relatively less affected by major climatic changes over long periods.
• They receive more solar energy, which can support higher productivity.
• Warm and relatively stable climatic conditions can support a large number of species.
• Longer periods of evolutionary diversification may have contributed to higher species richness.

4. Species-Area Relationship

The relationship between the number of species and the area of a region was studied by Alexander von Humboldt.

He observed that within a region, species richness generally increases with increasing explored area, but only up to a certain limit.

The relationship can be represented as:

S = C A^Z

Where:

• S = Species richness
• A = Area
• C = Constant
• Z = Regression coefficient or slope of the species-area relationship

On a logarithmic scale:

log S = log C + Z log A

Thus, a plot of log S against log A gives a straight line.

5. Species-Area Relationship in Large Areas

For relatively small areas, species richness generally increases with area in a regular manner.

For very large areas, the relationship can show a different slope. In studies of very large areas, the value of Z is often much steeper than that observed for smaller areas.

NCERT discusses this relationship in the context of conservation because destruction of a large habitat can result in significant species loss.

Why is Biodiversity Important?

6. Importance of Biodiversity

Biodiversity is important for the functioning and stability of ecosystems as well as for human welfare.

Ecological Importance

• Different species perform different ecological roles.
• Biodiversity supports food webs and nutrient cycling.
• It contributes to ecosystem stability and resilience.
• It supports processes such as pollination, decomposition and soil formation.

Economic Importance

Humans obtain numerous useful products from biodiversity, including food, medicines, fibres, timber and other biological resources.

Direct and Indirect Values

Biodiversity has direct use values because humans directly use many biological resources. It also has indirect use values because ecosystems provide services such as pollination, climate regulation, water purification and soil conservation.

Ethical Value

Every species has an intrinsic value (स्वाभाविक महत्व). Humans have a responsibility to protect other living organisms and the ecosystems on which life depends.

Biodiversity Loss

7. What is Biodiversity Loss?

Biodiversity loss means a decline in the variety, abundance or distribution of organisms in a region or on Earth.

Species may become rare, threatened or completely extinct due to natural and, increasingly, human-induced causes.

8. The Evil Quartet

NCERT describes four major causes of biodiversity loss as the “Evil Quartet”.

Cause	Meaning	Example / Effect
Habitat loss and fragmentation	Destruction and breaking up of natural habitats	Forest clearing for agriculture and development
Over-exploitation	Excessive use of biological resources	Overfishing, excessive hunting
Alien species invasions	Introduction of non-native species that harm native species	Water hyacinth, Lantana
Co-extinctions	Extinction of one species following the extinction of another species on which it depends	Host-specific parasites and their hosts

9. Habitat Loss and Fragmentation

Habitat loss occurs when a natural habitat is destroyed or converted into another land-use type.

Habitat fragmentation occurs when a large continuous habitat is divided into smaller isolated patches.

Fragmentation can make movement, breeding and feeding difficult for organisms and may increase their vulnerability to local extinction.

Large-scale habitat destruction is one of the most important causes of biodiversity loss.

10. Over-exploitation

Over-exploitation occurs when humans use a biological resource at a rate faster than its natural ability to recover.

Examples include:

• Excessive hunting
• Overfishing
• Unsustainable collection of medicinal plants
• Excessive harvesting of forest products

When exploitation becomes severe, populations may decline and species may become threatened or extinct.

11. Alien Species Invasions

An alien species is a species introduced into an area outside its natural geographical range.

Some alien species become invasive and negatively affect native species.

Important NCERT examples include:

• Parthenium
• Lantana
• Eichhornia (water hyacinth)

Invasive species may compete with native organisms for food, space and other resources.

12. Co-extinction

Co-extinction occurs when the extinction of one species causes the extinction of another species that depends closely on it.

For example, if a host-specific parasite loses its only host species, the parasite may also become extinct.

This shows that species are interconnected through ecological relationships.

Conservation of Biodiversity

13. What is Biodiversity Conservation?

Biodiversity conservation means protecting species, genetic diversity and ecosystems and ensuring their sustainable use for the future.

Two major approaches are:

• In situ conservation
• Ex situ conservation

14. In Situ Conservation

In situ conservation means conserving organisms in their natural habitats.

इस method में species को उनके natural environment में ही protect किया जाता है, जिससे ecological interactions और evolutionary processes भी continue रह सकते हैं।

Major examples include:

• Biosphere reserves
• National parks
• Wildlife sanctuaries
• Sacred groves

15. Biosphere Reserves

A biosphere reserve is a large protected area designed to conserve biodiversity along with the sustainable use of natural resources.

Biosphere reserves can contain different zones with varying degrees of protection and human activity.

16. National Parks

National parks are protected areas established for the conservation of wildlife and their habitats.

Human activities are generally more strictly regulated in national parks than in many other protected areas.

17. Wildlife Sanctuaries

Wildlife sanctuaries are protected areas where wildlife and habitats are conserved. Certain regulated human activities may be permitted depending on the rules of the sanctuary.

18. Sacred Groves

Sacred groves are patches of natural vegetation protected by local communities because of traditional or cultural beliefs.

They provide important refuges for many plants and animals and help conserve biodiversity.

Examples occur in the Khasi and Jaintia Hills of Meghalaya, the Western Ghats and other parts of India.

19. Biodiversity Hotspots

Biodiversity hotspots are regions with exceptionally high species richness and a high degree of endemism that are also under significant threat.

Endemic species are species naturally restricted to a particular geographical region.

20. In Situ vs Ex Situ Conservation

In Situ Conservation	Ex Situ Conservation
Conservation in natural habitat	Conservation outside natural habitat
Natural ecological interactions are maintained	Organisms are maintained under controlled conditions
Examples: National parks, wildlife sanctuaries, biosphere reserves	Examples: Zoos, botanical gardens, seed banks

21. Ex Situ Conservation

Ex situ conservation means conserving threatened organisms outside their natural habitats.

It is particularly useful when a species is critically threatened or when its natural habitat has been severely damaged.

Examples include:

• Zoological parks
• Botanical gardens
• Seed banks
• Gene banks
• Field gene banks
• Cryopreservation

22. Cryopreservation

Cryopreservation is the preservation of biological material at extremely low temperatures, commonly using liquid nitrogen.

It can be used for preserving germplasm, cells, tissues, embryos and other biological material for long-term conservation.

23. Seed Banks

Seed banks store seeds under controlled conditions so that plant genetic resources can be preserved for future use.

They are an important method of ex situ conservation.

24. Conservation Strategies in India

India has a wide variety of ecosystems and species. Conservation efforts include protected areas, species-specific programmes, legislation and community participation.

Examples of conservation approaches include:

• Protected areas
• Wildlife conservation programmes
• Habitat restoration
• Afforestation and reforestation
• Community-based conservation
• Sustainable use of natural resources

25. Why Should Biodiversity Be Conserved?

Biodiversity conservation is necessary because the loss of species can disturb ecological processes and reduce ecosystem resilience.

Conservation also protects genetic resources that may be useful for agriculture, medicine and future scientific research.

Protecting biodiversity ultimately means protecting the ecological systems that support human life.

26. Important Terms

Term	Meaning
Biodiversity	Variety and variability of living organisms
Genetic diversity	Variation within a species
Species diversity	Variety of species in a region
Ecosystem diversity	Variety of ecosystems
Endemic species	Species restricted naturally to a particular region
Hotspot	Highly threatened region with high endemism and rich biodiversity
In situ conservation	Conservation in natural habitat
Ex situ conservation	Conservation outside natural habitat
Co-extinction	Extinction of one species following the extinction of another closely associated species

27. Very Short Answer Questions

1. What is biodiversity?
2. Name the three levels of biodiversity.
3. What is genetic diversity?
4. What is species diversity?
5. What is ecosystem diversity?
6. What is a biodiversity hotspot?
7. What is an endemic species?
8. What is a latitudinal gradient?
9. Write the species-area relationship.
10. What is habitat fragmentation?
11. What is over-exploitation?
12. What is co-extinction?
13. What is in situ conservation?
14. What is ex situ conservation?
15. What is cryopreservation?

28. Short Answer Questions

1. Explain the three levels of biodiversity with examples.
2. Describe the latitudinal gradient of biodiversity.
3. Why is biodiversity generally higher in tropical regions?
4. Explain the species-area relationship.
5. What is habitat loss and fragmentation? Explain their effect on biodiversity.
6. Explain the “Evil Quartet” responsible for biodiversity loss.
7. How do alien species cause biodiversity loss?
8. Explain co-extinction with an example.
9. Differentiate between in situ and ex situ conservation.
10. Explain the importance of sacred groves in biodiversity conservation.

29. Long Answer Questions

1. Explain the major patterns of biodiversity with reference to latitudinal gradient and species-area relationship.
2. Describe the major causes of biodiversity loss known as the “Evil Quartet”.
3. Explain the different methods of biodiversity conservation.
4. Differentiate between in situ and ex situ conservation and give suitable examples.
5. What are biodiversity hotspots? Explain their significance in conservation.
6. Explain why biodiversity is important for ecosystem functioning and human welfare.

30. Multiple Choice Questions

1. The variety of genes within a species is called:

   (A) Species diversity   (B) Genetic diversity   (C) Ecosystem diversity   (D) Community diversity

   Answer: (B) Genetic diversity

2. Species diversity is generally highest in:

   (A) Polar regions   (B) Temperate regions   (C) Tropical regions   (D) Arctic regions

   Answer: (C) Tropical regions

3. The species-area relationship was studied by:

   (A) Charles Darwin   (B) Alexander von Humboldt   (C) Mendel   (D) Watson

   Answer: (B) Alexander von Humboldt

4. The species-area relationship is represented by:

   (A) S = CA^Z   (B) S = C + A   (C) S = Z/A   (D) S = A/C

   Answer: (A) S = CA^Z

5. Which is NOT included in the “Evil Quartet”?

   (A) Habitat loss   (B) Over-exploitation   (C) Photosynthesis   (D) Alien species invasion

   Answer: (C) Photosynthesis

6. Which is an example of an invasive alien plant in India?

   (A) Lantana   (B) Wheat   (C) Rice   (D) Mango

   Answer: (A) Lantana

7. Extinction of a species following the extinction of another closely associated species is called:

   (A) Adaptive radiation   (B) Co-extinction   (C) Mutation   (D) Migration

   Answer: (B) Co-extinction

8. Conservation of species in their natural habitat is called:

   (A) Ex situ conservation   (B) In situ conservation   (C) Artificial selection   (D) Hybridisation

   Answer: (B) In situ conservation

9. Which is an example of ex situ conservation?

   (A) National park   (B) Wildlife sanctuary   (C) Seed bank   (D) Biosphere reserve

   Answer: (C) Seed bank

10. Sacred groves are important because they:

    (A) Destroy natural vegetation   (B) Conserve natural vegetation and biodiversity   (C) Increase pollution   (D) Promote over-exploitation

    Answer: (B) Conserve natural vegetation and biodiversity

11. Cryopreservation generally uses:

    (A) Hot water   (B) Liquid nitrogen   (C) Carbon dioxide only   (D) Oxygen

    Answer: (B) Liquid nitrogen

12. A species restricted naturally to a particular geographical region is called:

    (A) Cosmopolitan   (B) Endemic   (C) Invasive   (D) Exotic

    Answer: (B) Endemic

13. Which conservation method preserves organisms outside their natural habitat?

    (A) In situ   (B) Ex situ   (C) Natural selection   (D) Habitat fragmentation

    Answer: (B) Ex situ

14. Which of the following can directly reduce biodiversity?

    (A) Habitat destruction   (B) Pollination   (C) Nutrient cycling   (D) Photosynthesis

    Answer: (A) Habitat destruction

15. Which of the following is an example of in situ conservation?

    (A) Zoo   (B) Botanical garden   (C) National park   (D) Seed bank

    Answer: (C) National park

31. Fill in the Blanks

1. The variety of living organisms is called ________.
2. Variation within a species is called ________ diversity.
3. Biodiversity generally decreases from the ________ towards the poles.
4. The species-area relationship is represented by S = ________.
5. Destruction and division of natural habitats is called habitat loss and ________.
6. Excessive use of biological resources is called ________.
7. Extinction of one species due to the extinction of another closely associated species is called ________.
8. Conservation in the natural habitat is called ________ conservation.
9. Conservation outside the natural habitat is called ________ conservation.
10. Long-term preservation of biological material at extremely low temperature is called ________.

Answers:

1. Biodiversity
2. Genetic
3. Equator
4. CA^Z
5. Fragmentation
6. Over-exploitation
7. Co-extinction
8. In situ
9. Ex situ
10. Cryopreservation

32. Assertion and Reason

1. Assertion: Tropical regions generally have greater species diversity than polar regions.

   Reason: Tropical regions have relatively stable climatic conditions and higher productivity.

   Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.

2. Assertion: Habitat fragmentation can increase the risk of local extinction.

   Reason: Fragmentation divides a continuous habitat into smaller isolated patches.

   Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.

3. Assertion: Ex situ conservation is carried out outside the natural habitat of an organism.

   Reason: Seed banks and zoological parks are examples of ex situ conservation.

   Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.

4. Assertion: Biodiversity hotspots are important for conservation.

   Reason: They combine high levels of endemism with significant threats to their habitats.

   Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion.

33. Match the Following

Column A	Column B
1. Genetic diversity	a. Conservation outside natural habitat
2. Endemic species	b. Variation within a species
3. Co-extinction	c. Species restricted to a region
4. In situ conservation	d. Extinction of closely associated species
5. Ex situ conservation	e. Conservation in natural habitat

Answers: 1-b, 2-c, 3-d, 4-e, 5-a

34. Quick Revision

35. Must Remember for Board Exam