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Factors afecting gene frequency class 12
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Aslam o alikum • I am Hassam ur Rahman and I am teaching Fsc biology since 2014 .I am always trying to improve myself and provide best lecture to students.i am taking content for the lecture from authentic and relevant sources but human errors are possible . you are requested to please highlight the mistakes.My lectures are equally reliable for Fsc and mdcat students • #visiblescience #mdcatbiology #alevelbiology #neetbiology #fscbiology • My personal channel, I am sure it will change your life and very beneficial for you • https://youtube.com/@hassamurRahman?f... • My Facebook page link • https://www.facebook.com/hassam.urahm... • This lecture is about • Factors afecting gene frequency • Many factors can alter gene frequency. Out of these ive afect the proportion of • homozygotes and heterozygotes enough to produce signiicant deviations form the • proportion claimed by Hardy Weinberg principle. They are relected in the table below. • Table 24.2 Factors for evolutionary change • Factor Description • Mutation The ultimate source of all changes; individual mutations occur so • rarely that mutation alone does not change allele frequency much. • Migration A very potent agent of change, migration locally acts to prevent • evolutionary changes by preventing populations that exchange • members from diverging from one another. Emigration and • immigration of members of a population, cause disturbance in the • gene pool. • Genetic drift It is the change in frequency of alleles at a locus that occurs by • chance. In small populations, such luctuations may lead to the loss • of particular alleles. This may occur in a small population when a • few individual fail to reproduce and then genes are lost from the • population. • Non-random mating Inbreeding is the most common form; it does not alter allele • frequency, but lessens the proportion of heterozyote individuals. • Individuals with certain genotypes sometimes mate with one another • more commonly than would be expected on a random basis. This • is called non-random mating, causing the frequencies of particular • genotypes to difer greatly from those predicted by the 1 lardy- • Weinberg principle. • Selection Some individuals leave behind more progeny than others, and the • rate at which they do so is afected by their inherited characteristics. • This is called selection. Selection can be artiicial selection or natural • selection. In artiicial selection, the breeders select for the desired • characters. In natural selection, the environment plays this role, thus • afecting the proportions of gene in a population.
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