• Robert McCredie May is a theoretical ecologist and promoter of science.
• He estimated that there are almost 7 million species globally.

• The mutualistic relationship between a fungus and photosynthesizing algae is called lichens.
• Of all the plant species recorded, lichens have the minimum number of species.
• They are used in the food industry, making dyes and have medicinal use.

Tropical rainforests are disappearing fastly from India due to deforestation, habitat loss and fragmentation. These forests are of extreme value since they contain the maximum biodiversity.

IUCN is International Union of Conservation of Nature and Natural Resources, which is now called world conservation Union (WCU). It has its headquarters at Morges, Switzerland. It maintains a Red Data Book or Red List which is a catalogue of taxa facing risk of extinction.

About 20% of the world oxygen is produced in the amazon rainforests. They are described as the 'lungs of the planet because they provide the assential world environmental service of continously recycling CO₂ into O₂ .

In the absence of their natural predators, exotic species flourish better and pose a threat to indigenous species.

Genetic diversity is the diversity in the numbers and types of genes as well as chromosomes present in different species and the variations in the genes and their alleles in the same species. The genetic variation in Rauwolfia vomitoria growing in different Himalayan range indicates genetic diversity. Another example is of presence of more than 50,000 genetically different strains of rice, and 1000 varieties of mango in  India.

Species diversity is the variety in the number and richness of the species of a region. Western ghats have greater amphibian species diversity as compared to Eastern ghats. The number of the species per unit area is called species richness. Number of individuals of different species represent species evenness or species equitability.

Keystone species are those which have significant and disproportionately large influence on the community structure and characteristics. It has often considerably low abundance and biomass as compared to dominant species. Removal of such species causes serious disruption in structure and function of community.

A. Beta diversity - Between community diversity
B. Rich biodiversity - Tropical areas
C. Gamma diversity - Diversity of whole geographical region
D. Extinct species - Dodo
E. Critically endangered species - Great Indian bustard