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The effective population size (N e) is the size of an idealised population that would experience the same rate of genetic drift as the real population. [1] Idealised populations are those following simple one- locus models that comply with assumptions of the neutral theory of molecular evolution .
In population genetics, the Watterson estimator is a method for describing the genetic diversity in a population. It was developed by Margaret Wu and G. A. Watterson in the 1970s. [1] [2] It is estimated by counting the number of polymorphic sites. It is a measure of the "population mutation rate" (the product of the effective population size ...
To calculate genetic diversity the authors multiply long term effective population size of the females by two, assuming sex ratio 1:1, and then multiply by mitochondrial genes substitution rate, per generation. Making several assumptions according to the sex ratio and number of juveniles, they were able to calculate that in contrast to ...
Based on a dataset of average population density of hunter-gatherer groups collected by Lewis R. Binford, which indicate a mean density of 0.1223 humans per km 2 and a median density of 0.0444 humans per km 2, the combined human population of Africa and Eurasia at the time of the LGM would have been between 2,998,820 and 8,260,262 people.
The effective population size (Ne), or the reproducing part of a population is often lower than the actual population size in small populations. [4] The Ne of a population is closest in size to the generation that had the smallest Ne. This is because alleles lost in generations of low populations are not regained when the population size increases.
Kimura and Ohta (1969) showed that a new mutation that eventually fixes will spend an average of 4N e generations as a polymorphism in the population. [2] Average time to fixation N e is the effective population size, the number of individuals in an idealised population under genetic drift required to produce an equivalent amount of genetic ...
where u is the mutation rate, and N e is the effective population size. The effective number of alleles n maintained in a population is defined as the inverse of the homozygosity, that is = = + which is a lower bound for the actual number of alleles in the population. If the effective population is large, then a large number of alleles can be ...
In population genetics and population ecology, population size (usually denoted N) is a countable quantity representing the number of individual organisms in a population. Population size is directly associated with amount of genetic drift , and is the underlying cause of effects like population bottlenecks and the founder effect . [ 1 ]