Biodiversity
உயிரியல் பன்முகத்தன்மை
Do not confuse biodiversity with mere species count. Edward Wilson defined it as the total biological organization from macromolecules to biomes. If you think it is just about animals, you have already lost a mark.
The idea
Biodiversity is the cumulative diversity at all levels of biological organization. It is categorized into three types: genetic diversity, species diversity, and ecological diversity. Genetic diversity refers to the variation in genes within a species, such as Rauwolfia vomitoria. Species diversity measures the variety of species in a region, like the Western Ghats versus the Eastern Ghats. Ecological diversity pertains to ecosystem-level variations like deserts, rain forests, and mangroves.
Why it matters
It exists as a result of millions of years of evolutionary processes, allowing life to adapt to various environmental conditions and maintain ecosystem stability.
NEET lens
NEET focuses on the examples provided in NCERT. Memorize the Rauwolfia vomitoria example for genetic diversity. Questions often ask to distinguish between genetic, species, and ecological diversity. Do not skip the definitions; they are frequently tested as 'Match the Following' or 'Statement-based' questions.
Clinical significance
Loss of genetic diversity leads to inbreeding depression, reducing the fitness of a population. In humans, this mirrors the risk of recessive genetic disorders in isolated populations. Ecosystem collapse follows the loss of keystone species, disrupting the biological services essential for human survival.
Introduction
Biodiversity is the term popularised by the sociobiologist Edward Wilson to describe the combined diversity at all the levels of biological organisation — genetic, species and ecological.
Core concept
Levels: genetic diversity (e.g. Rauwolfia vomitoria in the Himalayas shows variation in the potency and concentration of reserpine; India has more than 50,000 genetically different strains of rice and 1,000 varieties of mango); species diversity (e.g. the Western Ghats have a greater amphibian species diversity than the Eastern Ghats); ecological diversity (India, with deserts, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows, has greater ecosystem diversity than a Scandinavian country like Norway). Number of species: according to the IUCN (2004), the total number of plant and animal species described so far is slightly more than 1.5 million; Robert May places the global species diversity at about 7 million. More than 70 per cent of all the species recorded are animals, while plants (including algae, fungi, bryophytes, gymnosperms and angiosperms) comprise no more than 22 per cent of the total; among animals, insects are the most species-rich group, making up more than 70 per cent of the total. Although India has only 2.4 per cent of the world's land area, its share of the global species diversity is an impressive 8.1 per cent — one of the 12 mega-diversity countries. The historic Convention on Biological Diversity ('The Earth Summit') held in Rio de Janeiro in 1992 called upon all nations to take appropriate measures for conservation of biodiversity and sustainable utilisation of its benefits.
Go deeper
Why conserve biodiversity: narrowly utilitarian (food, fibre, medicines — bioprospecting), broadly utilitarian (ecosystem services such as oxygen production, pollination, aesthetic pleasure) and ethical (every species has intrinsic value).
From Class 10
Biodiversity is the variety of life — different genes, different species and different ecosystems.