14 public questions tagged with this topic.
Species with small populations are more vulnerable because they are more susceptible to habitat loss, environmental changes, and genetic problems.
Ref: NCERT Class 12 Biology Chapter 13: Biodiversity and Conservation Loss of Biodiversity - Causes - Habitat Loss Overexploitation
Threatened spectrum under IUCN comprises Vulnerable, Endangered, and Critically Endangered, representing increasing risk. Critically Endangered CR denotes species facing extremely high extinction risk imminently, defined by thresholds such as population reduction exceeding 90% over ten years, extent of occurrence below 100 km² with fragmentation, population below 250 mature individuals declining, or quantitative analysis showing 50% extinction probability in ten years. CR listing triggers urgent recovery planning, legal protection under Schedule I, and priority funding. This example illustrates how ecological adaptations correlate with biogeographic zonation and conservation prioritization in Indian context.
Ref: IUCN Red List Category CR Thresholds; Wildlife Protection Act 1972 Schedule I Correspondence
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
“Isolated small islands” for the highest risk of extinction is usually found on. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. At equilibrium, species identities can continue to turn over even when richness is approximately stable. The model predicts a balance of rates, not an absence of colonization or extinction. The remaining alternatives—“Isolated large islands”, “Islands close to the mainland”, “Large continental islands”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Island biogeography explains species richness as a dynamic balance between immigration and extinction. Immigration generally declines as an island fills with species, whereas extinction rises as more species divide finite area and maintain smaller populations. Linking the wording to measurable consequences for fitness, abundance, or flux gives the conclusion its scientific meaning and prevents a purely mnemonic interpretation.
Ref: Biogeography, Lomolino et al., 5th Ed., Ch. 1-4
“Narrow niche and limited environmental tolerance” for specialists species are more prone to extinction due to. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Habitat describes where an organism occurs; niche additionally describes how it obtains resources and affects or responds to other organisms. Distribution therefore provides evidence about a niche but is not identical to it. The remaining alternatives—“Broad niche”, “High reproductive rates”, “Generalist diet”—refer to different states, processes, or scales and therefore do not express the same causal relationship. A niche is the multidimensional set of abiotic conditions, resources, and biotic relationships under which a population can persist. The fundamental niche reflects physiological and resource limits, while the realized niche is modified by competitors, consumers, mutualists, and dispersal barriers. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates.
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 13
A strong Allee effect creates a critical abundance or density at which population growth changes sign. Above the threshold, births can exceed deaths and recovery is possible; below it, mate limitation, inbreeding, or failure of cooperation makes growth negative and drives further decline. The threshold is therefore an unstable equilibrium with direct importance for conservation and biological invasions. Density dependence is identified by a change in a per-capita demographic rate as abundance changes. Negative density dependence restrains growth and can regulate abundance; positive density dependence can make sparse populations vulnerable. A factor can affect population size without regulating it if its impact does not create a restoring response to density. The decisive distinction is therefore between a descriptive label and the demographic mechanism that generates it. Interpreting the example at the appropriate population scale keeps the causal mechanism distinct from a simple correlation or an absolute rule. Ecological predictions remain conditional on the stated environment, because changing resources, mortality, or interactions can alter the observed demographic pattern.
Ref: Ecology: From Individuals to Ecosystems, Begon et al., 5th Ed., Ch. 5
“Generalist species” for which of the following is least associated with extinction risk. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Extinction risk rises when abundance, geographic range, or genetic variation becomes small because demographic chance, environmental fluctuations, inbreeding, and rare catastrophes then have disproportionate effects. Correlated losses among subpopulations further weaken regional persistence. The remaining alternatives—“Narrow niche width”, “Top predator status”, “Habitat fragmentation”—refer to different states, processes, or scales and therefore do not express the same causal relationship. The mechanism should be evaluated across both local and global scales. Local disappearance can be reversed by recolonization, whereas global extinction is irreversible and requires the loss of every surviving population. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit.
Ref: Conservation Biology, Primack & Sher, 6th Ed., Ch. 7
“Increases extinction risk” for high population size variability. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Extinction risk rises when abundance, geographic range, or genetic variation becomes small because demographic chance, environmental fluctuations, inbreeding, and rare catastrophes then have disproportionate effects. Correlated losses among subpopulations further weaken regional persistence. The remaining alternatives—“Reduces extinction risk”, “Maintains stability”, “Is unrelated to extinction”—refer to different states, processes, or scales and therefore do not express the same causal relationship. The mechanism should be evaluated across both local and global scales. Local disappearance can be reversed by recolonization, whereas global extinction is irreversible and requires the loss of every surviving population. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit.
Ref: Conservation Biology, Primack & Sher, 6th Ed., Ch. 7
“They cannot sustain population declines” for short lifespan species are more extinction-prone because. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. The mechanism should be evaluated across both local and global scales. Local disappearance can be reversed by recolonization, whereas global extinction is irreversible and requires the loss of every surviving population. The remaining alternatives—“They reproduce excessively”, “They overpopulate rapidly”, “They are r-strategists”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Human-driven habitat conversion, exploitation, introduced enemies, pollution, and climate change often interact rather than acting independently. Traits such as slow reproduction or ecological specialization can magnify vulnerability. Linking the wording to measurable consequences for fitness, abundance, or flux gives the conclusion its scientific meaning and prevents a purely mnemonic interpretation. Field observations could test this account by measuring the proposed driver and the demographic or ecosystem response while controlling plausible confounding factors.
Ref: Conservation Biology, Primack & Sher, 6th Ed., Ch. 7
“High” for reproductive ability reduces extinction risk when it is. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Extinction risk rises when abundance, geographic range, or genetic variation becomes small because demographic chance, environmental fluctuations, inbreeding, and rare catastrophes then have disproportionate effects. Correlated losses among subpopulations further weaken regional persistence. The remaining alternatives—“Cyclic”, “Low”, “Delayed”—refer to different states, processes, or scales and therefore do not express the same causal relationship. The mechanism should be evaluated across both local and global scales. Local disappearance can be reversed by recolonization, whereas global extinction is irreversible and requires the loss of every surviving population. Linking the wording to measurable consequences for fitness, abundance, or flux gives the conclusion its scientific meaning and prevents a purely mnemonic interpretation. Field observations could test this account by measuring the proposed driver and the demographic or ecosystem response while controlling plausible confounding factors.
Ref: Conservation Biology, Primack & Sher, 6th Ed., Ch. 7
“Low trophic status” for which is a less prone trait to extinction. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Human-driven habitat conversion, exploitation, introduced enemies, pollution, and climate change often interact rather than acting independently. Traits such as slow reproduction or ecological specialization can magnify vulnerability. The remaining alternatives—“High homozygosity”, “Small population size”, “High variability”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Extinction risk rises when abundance, geographic range, or genetic variation becomes small because demographic chance, environmental fluctuations, inbreeding, and rare catastrophes then have disproportionate effects. Correlated losses among subpopulations further weaken regional persistence. This distinction matters because similar surface patterns can arise through different mechanisms, whereas ecological prediction depends on identifying the mechanism that actually changes rates. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit.
Ref: Conservation Biology, Primack & Sher, 6th Ed., Ch. 7
“They depend on a single or few resources” for species with highly specialized diets are at higher risk because. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Extinction risk rises when abundance, geographic range, or genetic variation becomes small because demographic chance, environmental fluctuations, inbreeding, and rare catastrophes then have disproportionate effects. Correlated losses among subpopulations further weaken regional persistence. The remaining alternatives—“They consume many food sources”, “They rely on unstable climates”, “They are top predators”—refer to different states, processes, or scales and therefore do not express the same causal relationship. The mechanism should be evaluated across both local and global scales. Local disappearance can be reversed by recolonization, whereas global extinction is irreversible and requires the loss of every surviving population. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit.
Ref: Conservation Biology, Primack & Sher, 6th Ed., Ch. 7
