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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.

See also[edit]

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/Population_size — Please support Wikipedia.
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1292 news items

LSE Media Policy Project (blog)
Tue, 16 Sep 2014 09:41:15 -0700

Black population size is significant in three policy areas: incarceration practices, conditions of confinement, and juvenile justice policies. States with larger Black populations are likely to be more punitive in each of these areas, after controlling ...
Tue, 16 Sep 2014 11:56:58 -0700

That doesn't necessarily make it the most violent city in the state, since the calculation is based upon population size. Focusing on the state's 26 cities with more than 100,000 residents, we divided each city's population size by the total number of ...
Thu, 18 Sep 2014 15:18:45 -0700

"We are already to a point where our population size is unsustainable," lead author of the paper, Jeffrey McKee, told mongabay.com earlier in the year. "In other words, we are already beyond the point of the biological concept of 'carrying capacity.'"


Thu, 18 Sep 2014 11:45:00 -0700

Contrary to previous projections, it now appears that the world's population is unlikely to stop growing this century. There's at least an 80% chance that between 9.6 and 12.3 billion humans will inhabit the Earth by 2100 — and much of this increase ...
New York Times
Thu, 18 Sep 2014 17:47:34 -0700

Georgia has seen major demographic shifts in recent years, with significant increases in African-American, Hispanic and Asian-American populations. The politics of Georgia, however, with gun control debates and harsh immigration laws, seem to lag ...


Fri, 19 Sep 2014 11:00:00 -0700

... U.S. intelligence agencies broadly forecasting that, by 2030, “Asia will have surpassed North America and Europe combined in terms of global power, based on GDP [gross domestic product], population size military spending and technological investment.”.

Alaska Dispatch

United States Geological Survey (press release)
Mon, 08 Sep 2014 10:03:45 -0700

In 2013 and 2014, the USGS, USFWS and the Alaska Department of Fish & Game jointly surveyed walruses in Bering Strait and the Chukchi Sea to estimate current age structures and test a new method of estimating population size using a genetic ...


Thu, 18 Sep 2014 02:00:00 -0700

Many governments of least-developed countries themselves recognize population size or density as impediments to climate-change adaptation, as noted by these two peer-reviewed studies. A case study in Ghana concluded that gender also matters to ...

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