Practice question

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 — <50 CR, <250 EN, <1000 VU. A species with fewer than 250 mature individuals experiencing rapid decline qualifies CR C2a, demanding genetic management and emergency captive measures. This pattern is frequently tested in NCERT-based competitive examinations requiring precise recall of taxonomic hierarchy principles.