13. BIODIVERSITY AND CONSERVATION

In our biosphere immense diversity (or heterogeneity) exists not only at the species level but at all levels of biological organisation ranging from macromolecules within cells to biomes. Biodiversity is the term popularised by the sociobiologist Edward Wilson to describe the combined diversity at all the levels of biological organisation. The most important of them are– (i) Genetic diversity: A single species might show high diversity at the genetic level over its distributional range. The genetic variation shown by the medicinal plant Rauwolfia vomitoria growing in different Himalayan ranges might be in terms of the potency and concentration of the active chemical (reserpine) that the plant produces. India has more than 50,000 genetically different strains of rice, and 1,000 varieties of mango. (ii) Species diversity: The diversity at the species level, for example, the Western Ghats have a greater amphibian species diversity than the Eastern Ghats. (iii) Ecological diversity: At the ecosystem level, India, for instance, with its deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows has a greater ecosystem diversity than a Scandinavian country like Norway.

Biodiversity refers to the variety of life forms on Earth, including diversity at genetic, species, and ecological levels. Each level is important for the health of ecosystems. Genetic diversity ensures that species can adapt to changes. Species diversity refers to the number of different species in an ecosystem, and ecological diversity refers to the variety of ecosystems. For instance, a region like the Western Ghats has a much larger variety of amphibians compared to the Eastern Ghats, highlighting how geographical features can influence species richness. In India, diverse habitats like rainforests and alpine meadows promote ecological diversity.

Think of biodiversity like a rich tapestry—each thread is a different species, and without any particular color or pattern, the tapestry loses its beauty and function. Just as removing threads from a tapestry weakens it, losing species diminishes the strength of an ecosystem.

The diversity of plants and animals is not uniform throughout the world but shows a rather uneven distribution. For many groups of animals or plants, there are interesting patterns in diversity, the most well-known being the latitudinal gradient in diversity. In general, species diversity decreases as we move away from the equator towards the poles. With very few exceptions, tropics (latitudinal range of 23.5° N to 23.5° S) harbour more species than temperate or polar areas.

Biodiversity is not evenly spread across the planet. The most well-known pattern is that species richness tends to decrease as you move from the equator to the poles. In tropical regions, such as near the equator, there is generally a greater variety of species. This could be due to factors like a stable climate and abundant sunlight, which foster a range of habitats that support various life forms.

Imagine a lush garden full of different colored flowers near the equator, thriving under the sun, compared to a barren patch in the far north under ice. The garden (the tropics) supports a vibrant ecosystem, while the barren land (the poles) has fewer plants and animals.

Does the number of species in a community really matter to the functioning of the ecosystem? For many decades, ecologists believed that communities with more species, generally, tend to be more stable than those with less species. What exactly is stability for a biological community? A stable community should not show too much variation in productivity from year to year; it must be either resistant or resilient to occasional disturbances (natural or man-made), and it must also be resistant to invasions by alien species.

Research suggests that ecosystems with higher species diversity tend to be more stable and productive. Stability means that an ecosystem can maintain its functions and not vary too much from year to year. A diverse community is better equipped to handle disturbances, whether those are natural disasters or human-induced. For instance, if a disease hits one species, others can fill in its role, maintaining the ecosystem's balance.

Think of an orchestra where each musician plays a unique instrument. If one musician is unable to play, the others can still produce a harmonious sound. Similarly, in an ecosystem, if one species decreases in number due to some disturbance, others can compensate, ensuring stability.

The biological wealth of our planet has been declining rapidly and the accusing finger is clearly pointing to human activities. The colonisation of tropical Pacific Islands by humans is said to have led to the extinction of more than 2,000 species of native birds. The IUCN Red List (2004) documents the extinction of 784 species...

Human activities have accelerated biodiversity loss at an alarming rate. Factors contributing to this loss include habitat destruction, over-exploitation of resources, introduction of invasive species, and co-extinction events where the extinction of one species leads to the extinction of another dependent species. For instance, when a particular fish that is crucial for a local ecosystem disappears, the plants and animals that rely on it may also vanish.

Imagine a row of dominoes; when one falls, it can trigger the entire row to collapse. In ecosystems, the loss of one species can lead to a chain reaction, resulting in the extinction of interconnected species and the overall weakening of the ecosystem.

Conservation of biodiversity can take two main forms: in situ (on-site) and ex situ (off-site) conservation. In situ conservation focuses on protecting species within their natural habitats, whereas ex situ conservation involves relocating species to protected environments such as zoos or botanical gardens.

In situ conservation seeks to protect biodiversity in the natural environment, ensuring that entire ecosystems are preserved, while ex situ conservation involves moving endangered species to safer settings for protection. Both strategies are crucial for maintaining biodiversity. For example, national parks represent in situ efforts, whereas a botanical garden where rare plants are grown represents ex situ conservation efforts.

Think of in situ conservation like nurturing a garden in your backyard, whereas ex situ conservation is like creating a seed bank. Both methods have their purpose—one grows the plants in their natural setting, and the other preserves them for future generations.

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