Shankar IAS Summary Biodiversity- 2 - Famous Books for UPSC Exam (Summary

The Red Data Book

The Red Data Book is a principal compilation that lists species identified as threatened by various agencies and organisations. It is published and regularly updated by the International Union for Conservation of Nature (IUCN), headquartered in Morges, Switzerland. The title uses the word Red to indicate the danger faced by both plants and animals worldwide. First issued in 1966 by the IUCN's Species Survival Commission (SSC), the Red Data Book provides a scientific basis and practical guide for conservation planning, policy formulation and management of species at risk.

• The publication gives comprehensive information on endangered mammals and birds and also includes less prominent organisms that are at risk of extinction.
• The Red Data Book organises species according to their level of threat and provides criteria for evaluation, distribution data and conservation measures where available.
• Within the publication, special page colour-coding is used symbolically: pink pages highlight critically endangered species, while green pages denote species that were once threatened but have recovered and are no longer considered at risk.
• Over time the number of entries on the pink pages has increased, reflecting growing pressures on biodiversity; the number of recovered species on green pages remains comparatively low.

IUCN Classification of Conservation Priority

(a) Extinct (EX)

A taxon is classed as Extinct when there is no reasonable doubt that the last individual has died out. This status is applied when exhaustive surveys throughout the taxon's known historic range, at appropriate times and seasons, fail to record a single living individual.

(b) Extinct in the Wild (EW)

A taxon is classed as Extinct in the Wild when it survives only in cultivation, in captivity, or as a naturalised population well outside its known historic range. The classification requires thorough surveys of known and expected habitats, at suitable times, throughout its historical range that show no records of living individuals in the wild.

Great India Bustard (Critically Endangered)

(c) Critically Endangered (CR)

A taxon is placed in the Critically Endangered category when the best available evidence indicates that it meets any of the criteria for being critically endangered.

• Criteria used to assess this category include a very large reduction in population (for example, a decline of >90% over the last 10 years), a very small number of mature individuals (for example, fewer than 50) and quantitative analyses indicating a high probability of extinction (for example, at least 50% probability within 10 years).

(d) Endangered (EN)

A taxon is assigned the Endangered status when available evidence shows it meets any of the criteria defined for this category.

• Criteria include a substantial reduction in population (for example, 70% over the last 10 years), a small population size (for example, fewer than 250 mature individuals), or a quantitative analysis showing a significant probability of extinction (for example, at least 20% within 20 years).

(e) Vulnerable (VU)

A taxon is classified as Vulnerable when the available evidence indicates it meets any of the criteria for vulnerability.

• Assessment criteria may include a marked reduction in population (for example, >50% over the last 10 years), a population size estimated to be fewer than 10,000 mature individuals, or a probability of extinction in the wild of at least 10% within 100 years.

Vulnerable Species

(f) Near Threatened (NT)

• A taxon is listed as Near Threatened when it has been evaluated against the criteria but does not presently satisfy the thresholds for Critically Endangered, Endangered or Vulnerable. It is close to qualifying for a threatened category or is likely to qualify in the near future.

(g) Least Concern (LC)

A taxon is classified as Least Concern when it has been evaluated and does not qualify for any of the threatened categories (Critically Endangered, Endangered, Vulnerable) or Near Threatened. This category includes widespread and abundant taxa.Least Concerm(h) Data Deficient (DD)

• A taxon is designated Data Deficient when there is inadequate information to make a direct or indirect assessment of its risk of extinction based on distribution and population status. This is not a threat category; it highlights the need for more research and data collection.

(i) Not Evaluated (NE)

• A taxon is placed in the Not Evaluated category when it has not yet been assessed against the IUCN criteria and its conservation status remains undetermined.

Important Species in an Ecosystem

Keystone Species

• A keystone species is one whose presence, absence or change in abundance has a disproportionately large effect on the structure and function of an ecosystem relative to its own abundance.
• The addition or removal of a keystone species results in significant changes in the abundance or occurrence of other species and can alter ecosystem processes.
• Top predators such as tigers, lions, crocodiles and large herbivores like elephants often act as keystone species because they regulate prey populations and influence vegetation structure and nutrient cycles.
• Conservation priorities frequently target keystone species because protecting them typically benefits many other species and helps maintain ecosystem integrity.
• The local extinction of a keystone species can lead to cascading effects and the degradation of the entire ecosystem. For example, certain tree species (such as ebony and Indian-laurel) may rely on bats for pollination; a decline in bat populations can impede regeneration of these trees and thereby alter habitat structure for dependent fauna.

Keystone Species

Indicator Species

• An indicator species is one whose presence, absence or abundance reflects a specific environmental condition and thus indicates the status of other species or of ecosystem health.
• Indicator species help define environmental traits such as pollution levels, disease outbreaks, species competition and the effects of climate change.
• They are often among the most sensitive species in a region and serve as early warning signals for ecosystem change, which makes them valuable for monitoring and conservation biology.
• Examples include fish, invertebrates, periphyton, macrophytes and certain seabirds (for example, the Atlantic Puffin) in marine systems; amphibians indicate the presence of certain chemicals, UV radiation effects and air/water pollution; and lichens are reliable indicators of air quality and sensitivity to sulphur dioxide.Indicator Species

Foundation Species

• A foundation species is a dominant primary producer that shapes an ecosystem by creating and maintaining habitat and by strongly influencing community structure and energy flow.
• Typical examples include kelp in kelp forest ecosystems and corals in coral reefs; these organisms form the physical framework of their ecosystems and support high biodiversity.
• Because foundation species contribute directly to habitat creation and stability, their loss can lead to substantial declines in overall ecosystem productivity and diversity.