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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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10256 news items


Science Now
Mon, 27 Oct 2014 13:03:45 -0700

The duo obtained data on death rates, average family size (i.e., fertility), and regional population size from the World Health Organization and the U.S. Census Bureau International Data Base. They created a computer model that projects human ...

Yorkshire Post

Yorkshire Post
Mon, 24 Nov 2014 01:00:00 -0800

The American researchers claim that neither conflict, disaster nor disease is likely to affect population size. Human numbers are growing by around 80 million every year, the same number as those who died in the 1918 influenza outbreak, or in the ...

New Security Beat

New Security Beat
Mon, 24 Nov 2014 03:37:30 -0800

... (in which the world moves towards sustainability, business as usual, inequality, conflict, or technological innovation) shape fertility, mortality, and education trends, and in doing so, influence population size and societies' adaptive and ...
Mon, 24 Nov 2014 09:03:45 -0800

Though the study had a long follow-up period and population size, it was not a randomized controlled trial, but such an intervention would be ethically impossible, the study authors write. “These findings might be the best evidence available and ...

The News-Press

The News-Press
Thu, 20 Nov 2014 18:15:00 -0800

“The number of roadkills we're seeing tracks closely with the trend in population size,” state panther biologist Mark Lotz said. “As the population increases, we're seeing a similar increase in roadkills: There are more panthers to get hit.” With a ...

EurekAlert (press release)

EurekAlert (press release)
Fri, 07 Nov 2014 01:56:15 -0800

Starting with the latest estimate for a founding population of about 400 people (including 170-230 women), and applying population growth rates in the range achieved by past and present populations, the researchers modelled the human population size ...

Korea IT Times (press release)

Korea IT Times (press release)
Thu, 30 Oct 2014 18:07:30 -0700

SEOUL, KOREA - The Constitutional Court ruled that the current law on the population size of voting districts is in violation of the constitution and recommended the population disparity between the largest and the smallest constituency, a ratio of ...
Sun, 09 Nov 2014 10:45:00 -0800

"We are using 'DNA fingerprints' to not only estimate the population size, but to determine differences in abundance and distribution in the various regions of the state, and identify potential barriers to gene flow — the population's ability to move ...

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