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A population cycle in zoology is a phenomenon where populations rise and fall over a predictable period of time. There are some species where population numbers have reasonably predictable patterns of change although the full reasons for population cycles is one of the major unsolved ecological problems.
The term and concept derive from a series of over-population experiments Calhoun conducted on Norway rats between 1958 and 1962. [1] In the experiments, Calhoun and his researchers created a series of "rat utopias" [ 2 ] – enclosed spaces where rats were given unlimited access to food and water, enabling unfettered population growth.
The history of scientific method considers changes in the methodology of scientific inquiry, not the history of science itself. The development of rules for scientific reasoning has not been straightforward; scientific method has been the subject of intense and recurring debate throughout the history of science, and eminent natural philosophers and scientists have argued for the primacy of ...
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 negative feedback mechanisms bring the population back down.
The 12 E. coli LTEE populations on June 25, 2008. [1]The E. coli long-term evolution experiment (LTEE) is an ongoing study in experimental evolution begun by Richard Lenski at the University of California, Irvine, carried on by Lenski and colleagues at Michigan State University, [2] and currently overseen by Jeffrey Barrick at the University of Texas at Austin. [3]
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.
Population models are used to determine maximum harvest for agriculturists, to understand the dynamics of biological invasions, and for environmental conservation. Population models are also used to understand the spread of parasites, viruses, and disease. [2] Another way populations models are useful are when species become endangered.
Life history theory (LHT) is an analytical framework [1] designed to study the diversity of life history strategies used by different organisms throughout the world, as well as the causes and results of the variation in their life cycles. [2]