directional selection
What directional selection means in Biology A-Level, as defined for AQA.
Definitions of directional selection
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Reference: AQA
Individuals at one extreme of the range have the advantage, so the modal value shifts in that direction over generations and the whole distribution curve moves along the axis.
Favours one extreme, so the whole curve shifts and the mean moves with it.
Topics that use directional selection
- Evolution may lead to speciation (A-level only) (AQA A-Level)
- Genetic diversity and adaptation (AQA A-Level)
Related terms
- stabilising selection
- advantage depends on environment
- allele
- allele frequency change
- allele passed to offspring
- allopatric speciation
- altered tertiary structure
- aseptic technique
Using directional selection in the exam
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