In population genetics and population ecology, population size (usually denoted N) is the number of individual organisms in a population.
The effective population size (Ne) is defined as "the number of breeding individuals in an idealized population that would show the same amount of dispersion of allele frequencies under random genetic drift or the same amount of inbreeding as the population under consideration." Ne is usually less than N (the absolute population size) and this has important applications in conservation genetics.
Small population size results in increased genetic drift. Population bottlenecks are when population size reduces for a short period of time.
Overpopulation may indicate any case in which the population of any species of animal may exceed the carrying capacity of its ecological niche.
Famous quotes containing the words population and/or size:
“It was a time of madness, the sort of mad-hysteria that always presages war. There seems to be nothing left but war—when any population in any sort of a nation gets violently angry, civilization falls down and religion forsakes its hold on the consciences of human kind in such times of public madness.”
—Rebecca Latimer Felton (1835–1930)
“For truly I tell you, if you have faith the size of a mustard seed, you will say to this mountain, ‘Move from here to there,’ and it will move; and nothing will be impossible for you.”
—Bible: New Testament, Matthew 17:20.