Biodiversity and its Conservation — Part 1: Biodiversity and its patterns: visual lesson, ISC Class 12 Biology

Lesson

Biodiversity

Part 1 — what biodiversity is, how it is distributed, and why it matters.

In this lesson you will

Distinguish genetic, species and ecosystem diversity, and state the global numbers and proportions of major taxa
Explain the latitudinal gradient and the species–area relationship (graph and equation)
Explain the rivet popper hypothesis and the narrowly utilitarian, broadly utilitarian and ethical reasons for conserving biodiversity

Concept

Three levels of biodiversity

Biodiversity exists at three levels.

Table of the three levels of biodiversity
Level	Example
Genetic diversity	Rauwolfia vomitoria in different Himalayan ranges varies in the potency of its chemical reserpine; India has over 50 000 strains of rice and about 1000 varieties of mango
Species diversity	The Western Ghats have a greater diversity of amphibian species than the Eastern Ghats
Ecological (ecosystem) diversity	India’s deserts, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows, far more than a Scandinavian country

Diagram

How many species are there?

The IUCN (2004) puts the number of described species at slightly more than 1.5 million; Robert May estimated the global total at about 7 million. More than 70 percent of recorded species are animals; plants are no more than 22 percent; among animals, insects are more than 70 percent.

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