13.3. Summary

Since life originated on earth nearly 3.8 billion years ago, there had been enormous diversification of life forms on earth. Biodiversity refers to the sum total of diversity that exists at all levels of biological organisation.

Biodiversity is a broad term that encompasses the variety of life forms on Earth. It reflects the diversity within species, between species, and across ecosystems. The concept highlights that biodiversity has developed over billions of years and is crucial for maintaining life's balance on our planet.

Think of biodiversity like a large library. Each book represents a different species. Just as a library is valuable for its diverse collection of books on different subjects, biodiversity is vital for the health of our planet as it includes various species living in different environments.

Of particular importance is the diversity at genetic, species and ecosystem levels and conservation efforts are aimed at protecting diversity at all these levels.

Biodiversity can be understood at three levels: genetic diversity refers to the variations within a species; species diversity refers to the number of different species in a particular area; ecosystem diversity pertains to the varying habitats, communities, and ecological processes. Conservation efforts seek to maintain these diverse levels to ensure ecological stability.

Imagine a garden: genetic diversity is like the different colors of flowers in the garden; species diversity is about having different kinds of plants and animals interacting; and ecosystem diversity refers to having various garden layouts, such as flower beds, vegetables, and ponds.

More than 1.5 million species have been recorded in the world, but there might still be nearly 6 million species on earth waiting to be discovered and named. Of the named species, > 70 per cent are animals, of which 70 per cent are insects. The group Fungi has more species than all the vertebrate species combined.

The current total of known species is just over 1.5 million, representing a fraction of what might exist on Earth. The significant majority of identified species are animals, particularly insects. Furthermore, fungi represent a tremendous diversity of life, often exceeding the variety of vertebrate animals, such as mammals and birds.

Think of it like exploring a huge city where you've only seen a small part. Each type of building in the city represents a different species. Just as there are many buildings still unseen in the city, many species remain undiscovered in nature, highlighting the vastness of our biological world.

Species diversity on earth is not uniformly distributed but shows interesting patterns. It is generally highest in the tropics and decreases towards the poles. Important explanations for the species richness of the tropics are: Tropics had more evolutionary time; they provide a relatively constant environment and, they receive more solar energy which contributes to greater productivity.

Species diversity decreases as one moves away from the equator towards the poles. The tropics are rich in biodiversity due to longer evolutionary times, stable environments that favor specialization, and abundant solar energy that boosts productivity and supports more species.

Consider the tropics as a bustling marketplace filled with many vendors (species) thriving in a warm and welcoming environment. In contrast, the poles are like a quiet corner of a small town, fewer vendors (species) due to harsh conditions. The marketplace allows for diverse interactions and flourishing business, just as the tropical regions allow for a multitude of species to coexist.

Earth’s fossil history reveals incidence of mass extinctions in the past, but the present rates of extinction, largely attributed to human activities, are 100 to 1000 times higher. Nearly 700 species have become extinct in recent times and more than 15,500 species (of which > 650 are from India) currently face the threat of extinction.

Throughout Earth's history, there have been several mass extinction events. However, today's extinction rates are alarmingly high, primarily due to human actions such as habitat destruction, pollution, and climate change. Many species are currently endangered, highlighting an urgent need for conservation efforts.

Imagine a large forest where many animals live happily. If humans start cutting down trees (habitat destruction) and polluting water sources, many animals will struggle to survive. Just like a forest losing its trees becomes less vibrant and alive, our planet is losing its richness as species disappear.

Earth’s rich biodiversity is vital for the very survival of mankind. The reasons for conserving biodiversity are narrowly utilitarian, broadly utilitarian and ethical.

Conserving biodiversity is essential for human survival due to direct economic benefits (like food and medicine), ecosystem services (such as clean air and water), and ethical considerations (responsibility towards other living beings). Protecting biodiversity ensures that future generations inherit a healthy and diverse planet.

Think of nature as a big bank account. The more species and ecosystems we have, the richer our account is. If we spend too much without saving (over-exploiting resources), we risk going bankrupt (losing biodiversity). It's crucial to maintain a balance to ensure resources are available for the long term.

Biodiversity conservation may be in situ as well as ex situ. In in situ conservation, the endangered species are protected in their natural habitat so that the entire ecosystem is protected.

Conservation can occur in two ways: in situ, where species are protected in their natural environments, and ex situ, where species are taken out of their habitats to be cared for in controlled environments like zoos or botanical gardens. Both strategies aim to preserve species and their ecosystems.

Consider a scenic park where a certain animal species lives. If we protect the park (in situ), the animals thrive on their own. But if the animals are endangered and can't survive in the park anymore, they might be taken to a wildlife refuge (ex situ) where they can be safe until they can return to their natural habitat.

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