How can natural selection lead to a change in allele frequency?

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Feb 10, 2018


  • See below:


  • Allele frequency is the frequency with which a particular allele occurs in a population .

  • Natural selection makes the survival more better so that the individual bearing these useful variations are enabled to reproduce and hence the number of progeny increases . Hence, natural selection leads to change in allelic frequencies.

  • The effects of natural selection on different traits can be :

  • STABILISING SELECTION : If nature favours those individuals in the population which posses the mean character value , then it leads to stabilization of the traits .example : human height. Tall , Dwarf and Medium sized individuals are the variant of this character . If the nature selects the medium sized individuals , then the selection is said to be stabilising . The peak of bell shaped graph gets higher and narrower as the nature tries to decrease the peripheral character value.

  • DIRECTIONAL SELECTION : If selection acts to eliminate one extreme form and supports the other extreme form then, the peak shifts in the direction which is selected by nature .In above mentioned example , if either tall or dwarf individuals are selected ( rather than medium sized ) .

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  • DISRUPTIVE SELECTION: If the selection does not favours the mean character value , rather favours both the peripheral character values then this kind of selection is called as Disruptive selection. Two peaks are formed at the two extremes of the curves and a kind of depression forms in the centre. Example: If the nature selects both tall as well as dwarf individuals but not the medium - height individuals.

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  • The graphical representation of three types of selections :

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Hope this will help u................

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