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:
“The paid wealth which hundreds in the community acquire in trade, or by the incessant expansions of our population and arts, enchants the eyes of all the rest; the luck of one is the hope of thousands, and the bribe acts like the neighborhood of a gold mine to impoverish the farm, the school, the church, the house, and the very body and feature of man.”
—Ralph Waldo Emerson (1803–1882)
“O hideous little bat, the size of snot,
With polyhedral eye and shabby clothes,”
—Karl Shapiro (b. 1913)