Biodiversity and Its Conservation: One Mark Questions, Book Back Answers and Notes

About Biodiversity and Its Conservation

Medium ~120 min study

Biodiversity is the variety of life on Earth at three levels: the genes within a species, the species in a region and the ecosystems they form. Human life depends on it. Food, medicines, clean water, fertile soil and a stable climate all come from working ecosystems. The chapter first describes how this variety is spread over the globe and why some regions hold far more species than others.

From patterns it moves to loss. The species-area relationship shows why shrinking habitats mean fewer species. Habitat fragmentation, over-exploitation, pollution and invasive alien species have pushed extinction rates far above the natural rate. The last part of the chapter turns to what can be done: protected areas, captive breeding, gene banks and the laws that support them.

For the exam, be clear on the difference between in-situ and ex-situ conservation, with examples of each. Learn the species-area equation \( \log S = \log C + Z \log A \) and what each symbol stands for. Know the biodiversity hotspots found in India and the IUCN Red List categories, and be ready to give one example for each.

What you'll learn

• Define biodiversity and explain its genetic, species and ecosystem levels with examples.
• Use the species-area relationship and its regression coefficient Z, and explain the latitudinal gradient in species richness.
• Explain how habitat fragmentation, over-exploitation and alien species invasions raise extinction rates.
• Compare in-situ and ex-situ conservation, with the advantages and limits of each.
• Describe the role of the IUCN, the Red Data Book and the National Biodiversity Authority.

Before you start

• Trophic levels, food chains and food webs in an ecosystem.
• The basics of organic evolution, natural selection and speciation.
• How genetic variation arises within a population.

Biodiversity and Its Conservation explained

Biodiversity and Conservation at a Glance

Levels and Patterns of Biodiversity

Biodiversity is studied at three levels. Genetic diversity is the variation of genes within a species and helps a population adapt. Species diversity is the number and variety of species in an area. Ecosystem diversity is the variety of communities and habitats in a region. Species richness falls as we move from the equator towards the poles. The tropics have had a stable climate for a long time, which allowed more species to evolve. Alexander von Humboldt showed that species richness rises with the area explored, up to a limit. On a log scale the relationship is a straight line: \( \log S = \log C + Z \log A \).

Importance of Biodiversity

A rich variety of species keeps ecosystem services running: nutrient cycling, soil formation and climate regulation. Paul Ehrlich's Rivet Popper Hypothesis compares an ecosystem to an aeroplane and its species to the rivets. Losing a few rivets may not make the plane unsafe at once, but each loss weakens it. Losing the rivets on the wings, which stand for key species, can bring the plane down. The point is that every species we lose weakens the ecosystem a little more.

Biogeographical Zones of India

India is one of the 17 megadiverse countries of the world and is divided into ten biogeographic zones based on climate, soil and living organisms. These range from the cold, dry Trans-Himalaya and the Thar desert to the Western Ghats and the Andaman and Nicobar Islands. India also contains parts of four global biodiversity hotspots. A hotspot is a region very rich in endemic species that is also losing its habitat fast. These areas supply biological resources and have great aesthetic and cultural value.

Causes of Biodiversity Loss

The main human causes are habitat loss and fragmentation, over-exploitation, pollution, climate change and invasive alien species. Fragmentation breaks a large forest into small isolated patches, which cuts migration routes and separates populations. Over-exploitation wiped out the passenger pigeon. Alien species such as the African catfish Clarias gariepinus threaten native fishes in Indian rivers. Deforestation, slash-and-burn (shifting) cultivation and co-extinction, where a species dies out because its host or partner has gone, add to the loss.

IUCN and the Red Data Book

The International Union for Conservation of Nature (IUCN) assesses the risk of extinction of species and publishes the Red Data Book, or Red List. Species are placed in categories such as Extinct, Critically Endangered, Endangered and Vulnerable. The list shows which groups are declining fastest. Scientists and governments use it to decide priorities, frame international agreements and plan recovery programmes.

In-Situ and Ex-Situ Conservation

In-situ conservation protects species in their natural habitat, so the whole ecosystem is saved along with them. National parks, wildlife sanctuaries, biosphere reserves and sacred groves are examples. Ex-situ conservation protects threatened species outside their natural habitat, under controlled conditions. Zoological parks, botanical gardens, gene banks and cryopreservation of gametes are used, and captive breeding in these places can save a species that is close to extinction.

The Biological Diversity Act

The Convention on Biological Diversity asks countries to share the benefits of biological resources fairly. India met this through the Biological Diversity Act, 2002. The Act set up the National Biodiversity Authority, with its headquarters in Chennai. The Authority controls commercial use of biological resources, protects traditional knowledge and makes sure local communities receive a fair share of the benefits.

Common mistakes to avoid

• Mixing up in-situ and ex-situ. In-situ means in the natural habitat, as in a national park; ex-situ means outside it, as in a zoo or gene bank.
• Writing that species richness increases towards the poles. It is the opposite: diversity is highest in the tropics and falls towards the poles.
• Assuming Z has the same value everywhere. For small regions Z is usually 0.1 to 0.2, but for very large areas such as whole continents the slope is much steeper, about 0.6 to 1.2.
• Thinking introduced species are harmless. Alien species such as the African catfish Clarias gariepinus and tilapia have harmed native fishes in Indian waters.
• Believing the Red Data Book lists only extinct species. Most entries are living species placed in threat categories such as Critically Endangered, Endangered and Vulnerable.

Test yourself on these with the practice test, then check the worked reasoning in the solved MCQs.

Frequently asked questions

What is the difference between genetic and species diversity?

Genetic diversity is the variation in genes within one species, which helps it adapt to change. India has more than 50,000 genetically different strains of rice, for example. Species diversity is the number and variety of species in an area. The Western Ghats, for example, have more amphibian species than the Eastern Ghats.

How does the species-area relationship work?

Alexander von Humboldt observed that the number of species in a region increases with the area explored, but only up to a limit. When plotted on log scales, the relationship is a straight line, \( \log S = \log C + Z \log A \), where S is species richness, A is area, C is the Y-intercept and Z is the slope (regression coefficient).

What is the Rivet Popper Hypothesis and who proposed it?

Paul Ehrlich proposed it. He compared an ecosystem to an aeroplane and its species to the rivets holding it together. Removing a few rivets may not make the plane unsafe straight away, but every loss weakens it. Removing rivets from a vital part such as the wings, like losing key species, can make the whole system fail.

Why are tropical regions richer in biodiversity than polar regions?

The tropics have been relatively undisturbed for millions of years and have a stable climate with little seasonal change, so species have had long periods to evolve and specialise. The tropics also receive more solar energy, which raises productivity and supports more species.

What is the difference between in-situ and ex-situ conservation?

In-situ conservation protects species inside their natural habitats, so the whole ecosystem is saved. National parks, wildlife sanctuaries and biosphere reserves are examples. Ex-situ conservation keeps species outside their natural habitats under human care, in botanical gardens, zoological parks, gene banks and through cryopreservation of gametes.

What is the purpose of the IUCN Red Data Book?

The Red Data Book, or Red List, published by the IUCN, records how close each assessed plant and animal species is to extinction. It uses nine categories, including Extinct, Critically Endangered, Endangered and Vulnerable. The list raises public awareness, helps set conservation priorities and guides international agreements.

What does the Biological Diversity Act, 2002 regulate?

The Act protects India's biodiversity and controls access to biological resources and the traditional knowledge linked to them. It set up the National Biodiversity Authority, headquartered in Chennai, which makes sure that benefits from commercial use of these resources are shared fairly with local communities.