7 public questions tagged with this topic.
The IUCN Red List includes plants, animals, fungi, and other organisms and classifies them according to their extinction risk.
Ref: NCERT Class 12 Biology Chapter 13: Biodiversity and Conservation Loss of Biodiversity - Alien Invasion Co-extinction Mass Extinction - Evil Quartet
IUCN small population criteria assess extinction vulnerability due to demographic stochasticity. Criterion C requires fewer than 250 mature individuals for CR, 2500 for EN, 10,000 for VU combined with continuing decline and specific subpopulation structure such as 90% in one subpopulation. Criterion D addresses very small populations without decline —
Ref: IUCN Criterion C and D Small Population Thresholds; Wildlife Institute of India Red List Training Material
Geographic range criteria incorporate two spatial concepts: Extent of Occurrence EOO, minimum convex hull encompassing all known occurrences, measuring spread risk, and Area of Occupancy AOO, occupied habitat within EOO measured on standardized 2×2 km grid cells, measuring habitat specialization. Both metrics fall under Criterion B, which also requires fragmentation, few locations, and continuing decline or extreme fluctuations. B1 thresholds address EOO less than 100 km² CR, B2 addresses AOO less than 10 km² CR, crucial for island endemics. Clarity on this principle prevents confusion between in-situ and ex-situ methods often interchanged in examination options.
Ref: IUCN Guidelines EOO and AOO Definitions Criterion B; ResearchGate IUCN Methodology Diagram
IUCN Red List employs five criteria A to E for quantitative risk evaluation. Criterion A focuses specifically on population reduction measured over ten years or three generations, using direct observation, decline in area of occupancy, exploitation levels, or habitat quality deterioration. Thresholds differentiate threat levels: 90% decline for CR, 70% for EN, 50% for VU. Application captures overexploited fisheries, logging-driven tree decline, or disease-induced amphibian crashes even when absolute population remains large, highlighting trend analysis criticality. Field identification relies on this character, making it essential for wildlife surveys and protected area management protocols.
Ref: IUCN Categories and Criteria Version 3.1 Criterion A Population Reduction; IUCN Guidelines Manual 2022
Near Threatened abbreviated NT is category for taxa that do not currently qualify as threatened but are close to vulnerable thresholds or likely to qualify soon without conservation intervention. Criteria proximity includes moderate decline near 30%, range approaching 20,000 km² EOO, or small population near 10,000 mature individuals. Many raptors, freshwater turtles, and sharks recently listed as NT reflect growing pressures. NT acts as early warning, prompting monitoring, sustainable harvest regulation, and proactive habitat protection before uplisting becomes necessary. Conservation strategies built on this knowledge support national biodiversity targets and sustainable livelihood planning for local communities.
Ref: IUCN Red List Definition Near Threatened NT; Guidelines for Applying NT Category SANBI
Within IUCN Red List framework, EW stands for Extinct in the Wild, indicating species that no longer exists in native natural habitats after exhaustive surveys, but persists in cultivation, captivity, or as established populations outside historic range. Examples include Franklinia alatamaha extinct in wild since early 1800s but cultivated, and Hawaiian crow Corvus hawaiiensis. EW is distinct from EX Extinct where no individuals survive anywhere. EW status encourages ex-situ breeding and potential reintroduction if habitat restored. Remembering this distinction is crucial for solving taxonomy application questions in GATE and CSIR-NET life sciences papers.
Ref: IUCN Categories and Criteria v3.1 EW Definition; SANBI IUCN Explained Extinct in Wild
Red Data Book was conceived by IUCN in 1964 under Sir Peter Scott, chairman of Survival Service Commission, to systematically document threatened species globally. It evaluates taxa against quantitative criteria for extinction risk, population trend, and distribution. Publication uses categories from Extinct to Least Concern, supported by detailed justification, maps, and threats analysis. Red Data Book provides scientific basis for national wildlife protection acts, CITES appendices, and conservation prioritization. Regional and national Red Data Books extend global assessments to local contexts. Such details are high-yield for NEET and CUET as they link morphological classification with modern molecular phylogeny insights.
Ref: IUCN Red List History Red Data Book 1964; Campbell Biology Chapter 56 Conservation Assessment
