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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 d N d t = r N {\displaystyle {\mathrm {d} N \over \mathrm {d} t}=rN} where the derivative d N / d t {\displaystyle dN/dt} is the rate of increase of the population, N is the ...
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 ...
Overpopulation or overabundance is a phenomenon in which a species' population becomes larger than the carrying capacity of its environment.This may be caused by increased birth rates, lowered mortality rates, reduced predation or large scale migration, leading to an overabundant species and other animals in the ecosystem competing for food, space, and resources.
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.
Population. A group of conspecific individuals that is demographically, genetically, or spatially disjunct from other groups of individuals. Aggregation. A spatially clustered group of individuals. Deme. A group of individuals more genetically similar to each other than to other individuals, usually with some degree of spatial isolation as well.
Osteoporosis is diagnosed when the bone mineral density is less than or equal to 2.5 standard deviations below that of a young (30–40-year-old [4]:58), healthy adult women reference population. This is translated as a T-score. But because bone density decreases with age, more people become osteoporotic with increasing age.
Population modeling became of particular interest to biologists in the 20th century as pressure on limited means of sustenance due to increasing human populations in parts of Europe were noticed by biologist like Raymond Pearl. In 1921 Pearl invited physicist Alfred J. Lotka to assist him in his lab.
Population biology. The term population biology has been used with different meanings. In 1971, Edward O. Wilson et al. used the term in the sense of applying mathematical models to population genetics, community ecology, and population dynamics. [1] Alan Hastings used the term in 1997 as the title of his book on the mathematics used in ...