Q.Explain Founder's effect and Bottleneck effect in brief. OR What is DNA-fingerprinting? Who developed this technique? Add a short note on principle of DNA-fingerprinting.
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Start your 14-day free trial to unlock the full solution →Founder's effect and bottleneck effect are both examples of genetic drift — random changes in allele frequency caused by chance sampling of a small population; OR DNA fingerprinting identifies an individual from unique, repetitive DNA sequence variations.
Founder's Effect:
When a small group of individuals migrates from a large population and colonises a new, geographically isolated habitat, the genetic constitution (allele frequencies) of this small founding group may, purely by chance, differ markedly from that of the parent population. As this group grows into a new population, its gene pool remains different in allelic frequency from the original — this drift occurring in a newly founded population is called the Founder Effect. Example: certain rare recessive disorders occur at unusually high frequency in some geographically/socially isolated founder communities.
Bottleneck Effect:
When a large population is suddenly and drastically reduced in size by a natural calamity (earthquake, flood, famine, epidemic), the surviving few individuals' gene pool may, by chance, no longer represent the genetic diversity of the original population — some alleles are lost entirely while others become over-represented. Even after the population size recovers, allele frequencies stay altered. This is called the Bottleneck Effect. Example: modern cheetah populations show very low genetic diversity due to a past population bottleneck.
Both are illustrations of genetic drift — evolutionary change due to chance rather than natural selection — and both matter for speciation and loss of genetic variability in small/isolated populations.
OR — DNA Fingerprinting:
DNA fingerprinting is a technique that detects variation (polymorphism) in specific, highly repetitive, non-coding DNA sequences called VNTRs (Variable Number of Tandem Repeats). Because the number of repeats varies from person to person (even between close relatives, though not between identical twins), the resulting pattern is unique to each individual — hence 'fingerprint'.
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