Types of Natural Selection

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What is Natural Selection?

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Natural selection is the process by which organisms better adapted to their environment tend to survive and produce more offspring. It is a key mechanism of evolution.

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What are the types of Natural Selection?

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The main types of natural selection are: 1. Directional Selection 2. Stabilizing Selection 3. Disruptive Selection.

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Define Directional Selection.

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Directional selection occurs when one extreme phenotype is favored over others, causing the allele frequency to shift in one direction.

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Give an example of Directional Selection.

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An example of directional selection is the increase in size of the peppered moth during the Industrial Revolution, where darker moths became more common due to pollution.

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Define Stabilizing Selection.

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Stabilizing selection favors intermediate phenotypes and reduces variation, leading to a decrease in extremes.

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Give an example of Stabilizing Selection.

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An example of stabilizing selection is human birth weight, where infants of average weight have higher survival rates than those who are very small or very large.

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Define Disruptive Selection.

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Disruptive selection occurs when extreme phenotypes are favored over intermediate phenotypes, leading to two or more contrasting phenotypes.

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Give an example of Disruptive Selection.

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An example of disruptive selection is seen in African seedcracker birds, where birds with either very large or very small beaks are favored, while those with medium-sized beaks are not.

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What is Sexual Selection?

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Sexual selection is a mode of natural selection where individuals with certain inherited characteristics are more likely than others to obtain mates.

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What is Artificial Selection?

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Artificial selection is the intentional breeding of plants or animals for specific traits, often guided by human intervention.