Ex-Situ Conservation :
It is conservation of selected rare plants/ animals in places outside their natural homes. It includes offsite collections and gene banks. Offsite Collections: They are live collections of wild and domesticated species in Botanical gardens, Zoological parks, Wildlife safari parks, Arborata (gardens with trees and shrubs). The organisms are well maintained for captive breeding programmes. As a result, many animals which have become extinct in the world continue to be maintained in Zoological Parks. As the number increases in captive breeding, the individuals are selectively released in the wild. In this way the Indian crocodile and gangetic dolphin have been saved from extinction.
Gene Banks:
Gene banks are a type of biorepository which preserve genetic materials. Seeds of different genetic strains of commercially important plants can be stored for long periods in seed banks, gametes of threatened species can be preserved in viable and fertile condition for long periods using cryopreservation techniques. However, it is not economically feasible to conserve all biological wealth and all the ecosystems. The number of species required to be saved from extinction far exceeds the conservation efforts.

The major functional attributes are:
1. continuity of nutrient cycles or biogeochemical cycles (N₂' C, H₂0, P, S cycles)
2. soil formation, conditioning or maintenance of soil health (fertility) by soil microbial diversity along with the different trophic members
3. increases ecosystem productivity and provide food resources
4. act as water traps, filters, water flow regulators and water purifiers (forest cover and vegetation)
5. climate stability (forests are essential for rainfall, temperature regulation, C0₂ absorption, which in turn regulate the density and type of vegetation)
6. forest resource management and sustainable development

The reasons for the richness of biodiversity in the Tropics are:
(i) Warm tropical regions between the tropic of Cancer and Capricorn on either side of equator possess congenial habitats for living organisms.
(ii) Environmental conditions of the tropics are favourable not only for speciation but also for supporting both variety and number of organisms.
(iii) The temperatures vary between 25°C to 35°C, a range in which most metabolic activities of living organisms occur with ease and efficiency.
(iv) The average rainfall is often more than 200 mm per year.
(v) Climate, seasons, temperature, humidity, photoperiods are more or less stable and encourage both variety and numbers.
(vi) Rich resource and nutrient availability.

General strategies in conservation:
(i) identify and protect all threatened species
(ii) identify and conserve in protected areas the wild relatives of all the economically important organisms
(iii) identify and protect critical habitats for feeding, breeding, nursing, resting of each species
(iv) resting, feeding and breeding places of the organisms should be identified and protected
(v) Air, water and soil should be conserved on priority basis
(vi) Wildlife Protection Act should be implemented
(vii) There are two aspects of conservation strategies
(1) In-situ conservation
(2) Ex-situ conservation

Species is considered extinct when none of its members are alive anywhere in the world. If individuals of a species remain alive only in captivity or other human controlled conditions, the species is said to be extinct in the wild. In both of these situations, the species would be considered globally extinct. A species in considered to be locally extinct when it is no longer found in an area it once inhabited but is still found elsewhere in the wild.
Types of extinctions:
(i) Natural extinction is a slow process of replacement of existing species with better adapted species due to changes in environmental conditions, evolutionary changes, predators and diseases. A small population can get extinct sooner than the large population due to inbreeding depression (less adaptivity and variation).
(ii) Mass extinction: The earth has experienced quite a few mass extinctions due to environmental catastrophes. A mass extinction occurred about 225 million years ago during the Permian, where 90% of shallow water marine invertebrates disappeared.
(iii) Anthropogenic extinctions: These are abetted by human activities like hunting, habitat destruction, over exploitation, urbanization and industrialization. Some examples of extinctions are Dodo of Mauritius and Steller's sea cow of Russia. Amphibians seem to be at higher risk of extinction because of habitat destruction.