According to David Tilman, greater the diversity, greater is the primary productivity. Can you think of a very low diversity man-made ecosystem that has high productivity?
The man-made ecosystems like agricultural field of paddy or wheat show very low diversity, but possess high productivity. These are also an example of monoculture.
What does 'Red' indicate in the IUCN Red list (2004)?
Red in the IUCN Red list (2004) refers to the taxa with the highest risk of extinction.
Explain as to how protection of biodiversity hot spots alone can reduce up to $30 \%$ of the current rate of species extinction.
The biodiversity hot spots are regions with very high level of species richness, especially those under threat from humans, thus their protection can reduce the current rate of extinction. These regions can be protected as biological reserves, national parks and sanctuaries.
What is the difference between endemic and exotic species?
Endemic species are native or indigenous species, which are restricted to a particular geographical region. Exotic or alien species are those species which are introduced from one geographical region to another geographical area. Exotic species may lead to disappearance of native species.
How does species diversity differ from ecological diversity?
Species diversity refers to the number and distribution of species in an area. It is expressed in terms of 'number of species per unit area' and also as number of individuals of different species in an area.
Ecological diversity refers to the diversity at ecosystem level. It is related to different types of ecosystem habitats e.g., terrestrial (forests, grasslands, etc.) and aquatic (freshwater and marine) ecosystems.