News tagged with population size
Big-mouthed babies drove the evolution of giant island snakes
Some populations of tiger snakes stranded for thousands of years on tiny islands surrounding Australia have evolved to be giants, growing to nearly twice the size of their mainland cousins. Now, new research ...
May 15, 2012 |
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Whale population size, dynamics determined based on ancient DNA
Estimates of whale population size based on genetics versus historical records diverge greatly, making it difficult to fully understand the ecological implications of the large-scale commercial whaling of the 19th and early ...
May 09, 2012 |
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Physicists Show that Correlated Environmental Variations Can Quicken Extinctions
(PhysOrg.com) -- In general, population extinction is a natural process. For one reason or another, an estimated 99.9% of all species that have lived on Earth are now extinct. However, the reasons for a species ...
Jan 13, 2009 |
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Researchers create first large-scale model of human mobility that incorporates human nature
For more than half a century, many social scientists and urban geographers interested in modeling the movement of people and goods between cities, states or countries have relied on a statistical formula called ...
Feb 27, 2012 |
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Buried Coins Key to Roman Population Mystery?
(PhysOrg.com) -- The first century BC in Italy was culturally a brilliant age, unequaled by any other period in Roman history. It was a time of Cicero, Caesar, Vergil, Horace and many other major literary ...
Oct 05, 2009 |
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Study finds human population expanded during late Stone Age
Genetic evidence is revealing that human populations began to expand in size in Africa during the Late Stone Age approximately 40,000 years ago. A research team led by Michael F. Hammer (Arizona Research Laboratory's Division ...
Jul 29, 2009 |
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Powerful mathematical model greatly improves predictions for species facing climate change
UCLA life scientists and colleagues have produced the most comprehensive mathematical model ever devised to track the health of populations exposed to environmental change.
Dec 03, 2011 |
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New analysis shows 'hobbits' couldn't hustle
A detailed analysis of the feet of Homo floresiensis—the miniature hominins who lived on a remote island in eastern Indonesia until 18,000 years ago -- may help settle a question hotly debated among paleontologists: how si ...
Other Sciences / Archaeology & Fossils
May 06, 2009 |
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Atlantic herring population trends linked to egg predation by haddock
(PhysOrg.com) -- NOAA scientists have developed a population model for Atlantic herring that links herring population trends to the size of the haddock population. The model also provides evidence that egg predation by haddock ...
Aug 09, 2011 |
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Study of wolves will help scientists predict climate effects on endangered animals
Scientists studying populations of gray wolves in the USA's Yellowstone National Park have developed a way to predict how changes in the environment will impact on the animals' number, body size and genetics, amongst other ...
Dec 01, 2011 |
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Bats keep separate households
(PhysOrg.com) -- The use of different resources by males and females exacerbates the estimation of population sizes. However, the monitoring of population sizes, particularly for rare and threatened species, ...
Mar 24, 2011 |
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Population trends: Another influence on climate change
Changes in population growth and composition, including aging and urbanization, could significantly affect global emissions of carbon dioxide over the next 40 years, according to a new study out next week.
Oct 11, 2010 |
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Bird populations near Fukushima are more diminished than expected
(PhysOrg.com) -- Low-level radiation in Fukushima Prefecture appears to have had immediate effects on bird populations, and to a greater degree than was expected from a related analysis of Chernobyl, an international ...
Feb 09, 2012 |
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Study pins factors behind geography of human disease
If your home region has a hot, wet climate and a lot of different kinds of birds and mammals living in it, there's a really good chance the region will also contain numerous kinds of pathogens that cause human diseases.
Apr 16, 2010 |
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Climate change causes larger, more plentiful marmots, study shows
This week, one of the world's foremost scientific journals will publish results of a decades-long research project founded at the University of Kansas showing that mountain rodents called marmots are growing ...
Jul 21, 2010 |
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Population size
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.
For more information about Population size, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
