#mark-recapture

Radioisopes and Field Biology methods

What is the assumption in mark-recapture method?

Mark-recapture approaches like Lincoln-Petersen estimator calculate population size from proportion of marked individuals recaptured. Validity rests on critical assumptions: population closure, marks not lost, and equal catchability. If certain animals are trap-shy or trap-happy, marked fraction becomes biased, under- or overestimating abundance. Equal probability of capture for every individual during each sampling event ensures random mixing of marked and unmarked animals. Assumptions about random death or birth are less central than capture equality, which directly affects estimator mathema

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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Population Ecology

Mark-recapture technique assumes:

“Both a and c are correct” for mark-recapture technique assumes. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Mechanistic support comes from showing how resource limitation, enemies, mate availability, or physiological stress changes demographic performance. A descriptive association alone does not establish regulation or causation. The remaining alternatives—“No new births or deaths occur”, “Marks affect individual survival”, “Population is closed”—refer to different states, processes, or scal

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Population Ecology

Which method involves marking individuals and later counting recaptures?

“Mark-recapture technique” for which method involves marking individuals and later counting recaptures. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Population ecology links individual births, deaths, immigration, and emigration to changes in abundance. Per-capita rates determine the direction of change, while density dependence creates feedback when crowding alters survival or reproduction. The remaining alternatives—“Quadrat method”, “Random sampling”, “Visual counting”—refer to different sta

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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Population Ecology

An estimate of population size by capturing, marking, and recapturing individuals is called:

“Lincoln-Peterson method” for an estimate of population size by capturing, marking, and recapturing individuals is called. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Mechanistic support comes from showing how resource limitation, enemies, mate availability, or physiological stress changes demographic performance. A descriptive association alone does not establish regulation or causation. The remaining alternatives—“Quadrat sampling”, “Line transect sampling”, “Visual estimation”—refer to diff

Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology

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In which scenario does mark-recapture fail?

High mortality between marking and recapture violates the closure and equal-survival assumptions of the simple Lincoln–Petersen estimator. If marked individuals die disproportionately or many die before mixing, the number of marked recaptures R falls. Because N is estimated as MC/R, an artificially small R inflates the population estimate. Even equal mortality among marked and unmarked animals can undermine the interpretation if population size changes substantially during the interval. A closed population, uniform mixing, and equal marking or capture probabilities support rather than defeat t

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

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Which parameter is NOT needed for mark-recapture estimation?

The Lincoln–Petersen estimate requires three counts: M, the number initially marked and released; C, the total number captured on the second occasion; and R, the marked individuals found within that second capture. The number unmarked in the second sample is C − R, so it is not mathematically independent but can help determine C when only marked and unmarked counts are recorded. Population sex ratio is unnecessary for the basic estimator because the marked proportion, not sex composition, drives N ≈ MC/R. Sex ratio becomes relevant only if capture probabilities differ by sex, sampling targets

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

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What is the correct combination for estimating population using mark-recapture?

A valid mark–recapture estimate requires information about the first marked sample, the size of a later capture, and how many marked individuals appear in that later capture. It also requires assumptions: marks are retained and recognized, marking does not alter survival or catchability, marked organisms mix into the population, sampling probabilities are comparable, and the population is effectively closed during the study interval. These conditions justify M/N ≈ R/C and hence N ≈ MC/R. The row refers to statements labeled A–E, but those statements are absent from the workbook’s question text

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

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From a field, 80 rats are marked and released. A month later, 100 rats are captured, 20 are marked. Estimate population

The Lincoln–Petersen estimator uses N ≈ MC/R. The initial marked release is M = 80 rats, the second capture contains C = 100 rats, and R = 20 of those are marked. Therefore N = 80 × 100/20 = 400 rats. Since marked animals constitute one-fifth of the recapture sample, the marked cohort is inferred to represent one-fifth of the whole population; five times 80 gives the same estimate. The method assumes that the population is effectively closed during the month, all animals have equal capture probability, marks remain visible and do not affect survival or behavior, and marked rats mix randomly wi

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

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In mark-recapture, 100 fish were marked. Later, 150 fish were captured, of which 25 were marked. Population estimate = ?

Using the Lincoln–Petersen relationship, the marked fraction in the population is equated to the marked fraction in the recapture sample: M/N ≈ R/C. Solving gives N ≈ MC/R, where M is the initial marked release, C is the total second capture, and R is the number of marked recaptures. Substituting M = 100, C = 150, and R = 25 yields N = 100 × 150/25 = 600 fish. The logic is also intuitive: one-sixth of the second catch is marked, so the original 100 marked fish are inferred to constitute one-sixth of the population. Reliable estimation requires a closed population between occasions, durable and

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

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A student marks 10 fish and releases them in a lake. On recapture, 15 fish are caught, 5 of which are marked. The estima

The Lincoln–Petersen mark–recapture estimator assumes that the fraction of marked individuals in the second sample approximates the marked fraction in the whole population. If M individuals were initially marked, C individuals are caught later, and R of that second catch carry marks, then M/N ≈ R/C. Rearranging gives N ≈ MC/R. Here M = 10, C = 15, and R = 5, so N = (10 × 15)/5 = 30 fish. The estimate relies on marked fish mixing thoroughly with unmarked fish, marks being retained and recognized, equal capture probabilities, and negligible births, deaths, immigration, or emigration between samp

Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 9

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