14 public questions tagged with this topic.
Climate stability does not directly regulate population size, whereas natality, mortality, and migration influence population dynamics. This follows from NCERT principle where the relation explains the outcome clearly for students in simple steps.
Ref: NCERT Biology Textbook for Class XI and XII (Botany section), Chapter: Biology - Botany portion covering relevant concept.
Availability of food and resources directly affects population size by influencing birth and death rates.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Adaptations - Morphological Physiological Behavioural
Density-dependent factors, such as disease, increase in effect as population density rises.
Ref: NCERT Class 12 Biology Chapter 11: Organisms and Populations Responses to Abiotic Factors - Regulate Conform Migrate Suspend
N=50 reflects key principle in quiz on genetic drift, where evolutionary mechanisms shape genetic variation and adaptation. In this context, N=50 aligns with experimental and theoretical evidence from population genetics, behavioral ecology and molecular phylogeny. Textbooks like Campbell Biology, Futuyma Evolution and Hartl Principles illustrate supporting data. Understanding why N=50 fits helps integrate natural selection, environment.
Ref: Hartl & Clark, Principles of Population Genetics, Chapter 7: Drift.
1/2N reflects key principle in quiz on genetic drift, where evolutionary mechanisms shape genetic variation and adaptation. In this context, 1/2N aligns with experimental and theoretical evidence from population genetics, behavioral ecology and molecular phylogeny. Textbooks like Campbell Biology, Futuyma Evolution and Hartl Principles illustrate supporting data. Understanding why 1/2N fits helps integrate natural selection, environment.
Ref: Hartl & Clark, Principles of Population Genetics, Chapter 7: Drift.
Diploid organisms carry two homologous copies of each autosome, each bearing one allele per locus. In census population of N individuals, each contributes two gene copies for any autosomal gene, so total allele count in gene pool equals 2 multiplied by N. This denominator is used to convert allele counts to frequencies; for example 100 individuals yield 200 alleles. For X-linked loci counts differ due to hemizygous males. Concept extends to ploidy generalizations: total allele number equals ploidy level times population size, essential for sampling variance in drift models.
Ref: Hartl & Clark, Principles of Population Genetics, 4th ed., Chapter 2: Allele Counting; Griffiths, Chapter 20: Diploid Totals
The keyed exception is “Allelopathy estimation.” In the context of which of these is not a method for determining population size or density, that statement differs from the governing ecological pattern and must be evaluated against the mechanism rather than accepted from wording alone. 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 sampling”, “Mark-recapture”, “
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
“Density” for population size per unit area is termed. This relationship follows from the ecological mechanism represented by the terms in the item, not merely from an association between their names. Interpretation must distinguish absolute population change from a per-capita rate and must state the time interval and population boundary. Age structure, dispersal, environmental variation, and delayed responses can all make observed trajectories depart from a simple model. The remaining alternatives—“Dispersion”, “Population growth”, “Population dynamics”—refer to different states, processes, o
Ref: Campbell Biology, Urry et al., 12th Ed., Unit 8 Ecology
With nonoverlapping generations and a constant net reproductive multiplier, abundance follows Nt = N0R0^t. Starting with 500 females and using R0 = 1.5, four successive generations give 500 × 1.5^4. Because 1.5^2 = 2.25 and 1.5^4 = 5.0625, the projected female population is 500 × 5.0625 = 2,531.25. Fractional individuals are acceptable as a deterministic expectation; an actual census would necessarily be an integer. The calculation assumes that R0 remains unchanged, generations are discrete, density dependence is absent, and the age structure can be represented by a single generation multiplie
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 11
If K - N equals zero, then N equals K. The density-dependent factor (K - N)/K in the logistic equation is therefore zero, and multiplying it by rN gives dN/dt = 0. Population size is at the model s carrying-capacity equilibrium, even though individuals continue to be born and die. Logistic predictions depend on assumptions that managers should not overlook. Carrying capacity changes with habitat and climate, and removing individuals may alter age structure, social organization, or genetic diversity. Thus an algebraic optimum is a benchmark, not a guarantee that a real harvested or conserved po
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 11
The absolute increase dN/dt under logistic growth is greatest when N equals half the carrying capacity. This follows from the product N(1 - N/K): one factor increases with N while the other decreases, and their product peaks at K/2. At very low N there are too few reproducers; at K, density limitation reduces net increase to zero. Graphically, logistic abundance through time is sigmoid, whereas its instantaneous increment plotted against abundance is a downward-opening parabola. Confusing these two plots leads to incorrect curve descriptions. The time trajectory approaches K, while the product
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 11
Populations described as r-selected often fluctuate widely. Their rapid reproduction permits abrupt increases after rain, disturbance, or release from enemies, but short-lived resources and density-independent events can cause equally abrupt declines. Such populations need not cycle regularly; variable captures their tendency to track unpredictable opportunities rather than remain close to a stable carrying capacity. 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, an
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12
