Wednesday, May 27, 2009

Stabilization Selection

Stabilization selection is the most common form of selection.Although the appearance of any species changes slowly over very long periods of time, they do occur. Selection pressures will tend to prevent change in a species once the species has become well-adapted to their environment. Selection works against individuals exhibiting variations in a trait that deviates from the current, well-adapted, average population.
The following graph illustrates stabilization selection will do to a population, in terms of a specific trait.

Stabilization selection occurs when the most common phenotypes within the population are most favourable for the environment in which it lives. By doing so, the extreme variation of a particular trait resulting in a population where the traits are ideal for the environment and selective pressures maintain these ideal traits and features. Mutations that differ from the well-adapted traits and features will be selected against.

Human babies are a prime example of stabilization selection. Most babies are shown being born just over 3 kg than any other weight. Babies with significantly lower weight are more likely to have mental defects and have a lower survival rate while babies at a heavier weight pose risks to themselves and the mother. Natural selection reduces the extreme variations of a particular trait.

Return to Types of Selection or proceed to Directional Selection

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