Origin and Evolution of Life — BIOLOGY STD 12 Science — Question
Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYOrigin and Evolution of Life4 Marks
Question
Directional selection.
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Answer
Natural selection bringing about directional change without disrupting the balance is called directional selection.
In a population when more individuals acquire characters which are other than the mean character value, then it is called directional selection.
Natural selection usually acts to eliminate one of the extremes of the phenotypic range and favour the other. E.g. systematic elimination of homozygous recessives.
Directional selection operates for many generations, it results in an evolutionary trend within a population and shifting a peak in one direction. E.g. Industrial melanism, DDT resistant mosquito, etc.
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