10 public questions tagged with this topic.
Type III survivorship curves, seen in species like frogs and oysters, have high juvenile mortality but long survival for adults.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Population Interactions - Mutualism and Amensalism
Type I survivorship curves are seen in species with high parental care, where most individuals survive to old age, such as humans.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Population Growth - Exponential and Logistic Models
Humans exhibit a Type I survivorship curve, where mortality is low in early and middle life but increases in old age.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Responses to Abiotic Factors - Regulate Conform Migrate Suspend
Ground squirrels are commonly represented by a Type II survivorship curve because their probability of dying is treated as approximately constant across much of life. On a semilogarithmic survivorship graph, a constant hazard produces a roughly straight decline. Real populations can depart from this ideal when juveniles, dispersers, or old individuals experience different risks, so the classification is a broad empirical approximation. A survivorship curve is built from a cohort life table by plotting the proportion alive at each age. Type I concentrates mortality late, Type II approximates a constant hazard, and Type III concentrates mortality early. These are descriptive models, so a species may shift between them when predators, care, climate, or habitat quality changes. The example should therefore be understood as an application of a general model, with its assumptions kept explicit. Ecological predictions remain conditional on the stated environment, because changing resources, mortality, or interactions can alter the observed demographic pattern.
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
Oysters release enormous numbers of larvae, but most die before reaching adulthood because they receive little parental protection and face predation, starvation, and unsuitable settlement sites. The few survivors may then live much longer. This concentration of mortality in the earliest age classes produces a strongly concave Type III survivorship curve rather than the late-life losses characteristic of Type I. A survivorship curve is built from a cohort life table by plotting the proportion alive at each age. Type I concentrates mortality late, Type II approximates a constant hazard, and Type III concentrates mortality early. These are descriptive models, so a species may shift between them when predators, care, climate, or habitat quality changes. The example should therefore be understood as an application of a general model, with its assumptions kept explicit. Ecological predictions remain conditional on the stated environment, because changing resources, mortality, or interactions can alter the observed demographic pattern.
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
A Type I curve shows high survival through juvenile and middle ages followed by steep mortality late in life. Iteroparity, repeated reproduction across several seasons, is often associated with this pattern because adults usually survive long enough to breed more than once. The association is not a definition: the curve records mortality by age, whereas iteroparity describes scheduling of reproduction. Survivorship and reproductive schedules are connected through allocation. An organism has finite energy for growth, maintenance, defense, and reproduction; investment in one function constrains the others. Natural selection does not pursue a universal ideal. It favors combinations that leave more surviving descendants under the mortality risks and resource patterns experienced by a population. A useful check is to ask what happens at the biological extremes and whether the proposed mechanism still makes sense. Interpreting the example at the appropriate population scale keeps the causal mechanism distinct from a simple correlation or an absolute rule.
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
“High juvenile mortality” for type iii curve shows. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Survivorship curves summarize age-specific mortality: Type I concentrates loss late in life, Type II approximates a constant hazard, and Type III concentrates loss early. They are empirical patterns, not rigid taxonomic rules. The remaining alternatives—“High early survival”, “Constant mortality”, “Low reproduction”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Selection favors the schedule that increases lifetime reproductive success under local mortality and resource conditions. Body size, development time, fecundity, parental investment, and generation length consequently tend to covary. 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: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
“Belding's ground squirrel” for which of the following shows a type ii curve. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Life-history traits reflect allocation among growth, maintenance, survival, and reproduction. Energy invested in many offspring cannot simultaneously be invested in large offspring, prolonged care, or future breeding, creating measurable trade-offs. The remaining alternatives—“Human”, “Oyster”, “Agave”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Survivorship curves summarize age-specific mortality: Type I concentrates loss late in life, Type II approximates a constant hazard, and Type III concentrates loss early. They are empirical patterns, not rigid taxonomic rules. 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: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
“Type I” for which curve in survivorship shows density-dependent mortality. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Survivorship curves summarize age-specific mortality: Type I concentrates loss late in life, Type II approximates a constant hazard, and Type III concentrates loss early. They are empirical patterns, not rigid taxonomic rules. The remaining alternatives—“Type II”, “Type III”, “Logistic”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Selection favors the schedule that increases lifetime reproductive success under local mortality and resource conditions. Body size, development time, fecundity, parental investment, and generation length consequently tend to covary. Field observations could test this account by measuring the proposed driver and the demographic or ecosystem response while controlling plausible confounding factors. 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: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
“Type III” for the survivorship curve for species with many offspring and low parental care is. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Life-history traits reflect allocation among growth, maintenance, survival, and reproduction. Energy invested in many offspring cannot simultaneously be invested in large offspring, prolonged care, or future breeding, creating measurable trade-offs. The remaining alternatives—“Type I”, “Type II”, “Type IV”—refer to different states, processes, or scales and therefore do not express the same causal relationship. Survivorship curves summarize age-specific mortality: Type I concentrates loss late in life, Type II approximates a constant hazard, and Type III concentrates loss early. They are empirical patterns, not rigid taxonomic rules. The cited framing is therefore most useful when treated as a conditional biological claim, with assumptions about scale and environmental context kept explicit.
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
