Related topics: population

How a declining environment affects populations

Stable ecosystems occasionally experience events that cause widespread death—for example, bacteria in the human gut may be wiped out by antibiotics, or ocean life may be depleted by overfishing. A new study from MIT physicists ...

Duckweed: The low-down on a tiny plant

Duckweeds are a treat for many aquatic animals like ducks and snails, but for pond owners, they're sometimes a thorn in the side. The tiny and fast-growing plants are of great interest to researchers, not at least because ...

Expansion of transposable elements offers clue to genetic paradox

Species often experience a genetic bottleneck that diminishes genetic variation after speciation or introduction into a new area. Though bottlenecks in population size always reduce fitness and evolutionary potential, introduced ...

Human impacts erode behavioral diversity in chimpanzees

Compared to other animals, chimpanzees show tremendous variation across groups in their behavior—from the types of tools they use in their feeding behavior to the specific gestures they use in communication. Research in ...

A new approach to an old question: How do we actually cooperate?

In the animal kingdom, birds band together to ward off predators, and honeybees work collectively to benefit the entire hive. Animals of the human persuasion can act cooperatively too, at times, though this behavior is not ...

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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.

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