Biodiversity and its Conservation
Class 12 Biology · Biology · Chapter 13
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Summary
This chapter discusses biodiversity, the variety and variability among living organisms and ecosystems, and the importance of conserving it. Biodiversity is described at three levels: genetic diversity (variation within a species), species diversity (variety of species) and ecological or ecosystem diversity (variety of habitats and communities). Patterns of biodiversity include the latitudinal gradient (diversity increases from the poles to the equator, with the tropics being richest) and the species-area relationship, expressed by Alexander von Humboldt as a rectangular hyperbola and a straight line on a logarithmic scale. The importance of biodiversity is explained through narrowly utilitarian, broadly utilitarian and ethical arguments, and the rivet-popper hypothesis illustrating ecosystem stability. Causes of biodiversity loss, the "Evil Quartet", include habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinctions. Conservation strategies are classified as in situ (protection in natural habitats through biosphere reserves, national parks, wildlife sanctuaries, sacred groves and biodiversity hotspots) and ex situ (protection outside natural habitats through zoological parks, botanical gardens, seed banks, cryopreservation and in vitro fertilisation). The chapter concludes with international efforts and conventions, such as the Earth Summit and the Convention on Biological Diversity, that aim to ensure the sustainable use and equitable sharing of biological resources.
Levels of biodiversityPatterns of biodiversityImportance of biodiversityLoss of biodiversity and the Evil QuartetIn situ conservationEx situ conservation
Key terms
Biodiversity
The variety and variability of life forms at genetic, species and ecosystem levels in a given region.
Species diversity
The variety of species present in a region or ecosystem.
Endemism
The phenomenon of a species being restricted to and found only in a particular geographical area.
In situ conservation
The conservation of species in their natural habitats, such as in national parks and sanctuaries.
Ex situ conservation
The conservation of species outside their natural habitats, such as in zoos and seed banks.
Biodiversity hotspot
A region with a very high level of species richness and a high degree of endemism that is under threat.
Extra questions & answers
Try one from this chapter
Which of the following is NOT a level of biodiversity?