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Negative density-dependence, or density-dependent restriction, describes a situation in which population growth is curtailed by crowding, predators and competition. [citation needed] In cell biology, it describes the reduction in cell division. When a cell population reaches a certain density, the amount of required growth factors and nutrients ...
Population density is the number of people per unit of area, usually transcribed as "per square kilometer" or square mile, and which may include or exclude, for example, areas of water or glaciers. Commonly this is calculated for a county, city, country, another territory or the entire world. The world's population is around 8,000,000,000 [3 ...
Delayed density dependence has been used by ecologists to explain population cycles. [2] Ecologists have been unable to successfully explain regular population cycles for many decades; delayed density dependence may hold the answer. [2] Here populations are allowed to increase above their normal capacity because there is a time lag until ...
Carrying capacity is only found during a density-dependent population. Density-dependent factors influence the carrying capacity are predation, harvest, and genetics, so when selecting the carrying capacity it is important to understand to look at the predation or harvest rates that influence the population (Stewart 2004).
A 1982 study by Templeton and Johnson showed that in a population of Drosophila mercatorum under K-selection the population actually produced a higher frequency of traits typically associated with r-selection. [37] Several other studies contradicting the predictions of r/K selection theory were also published between 1977 and 1994. [38] [39 ...
The rate at which a population increases in size if there are no density-dependent forces regulating the population is known as the intrinsic rate of increase.It is = where the derivative / is the rate of increase of the population, N is the population size, and r is the intrinsic rate of increase.
Allee effects are classified by the nature of density dependence at low densities. If the population shrinks for low densities, there is a strong Allee effect. If the proliferation rate is positive and increasing then there is a weak Allee effect. The null hypothesis is that proliferation rates are positive but decreasing at low densities.
At this point, called the maximum sustainable yield, there is a surplus of individuals that can be harvested because growth of the population is at its maximum point due to the large number of reproducing individuals. Above this point, density dependent factors increasingly limit breeding until the population reaches carrying capacity.