Genetic Drift

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Apart from natural selection what is another process by which evolution occurs?
Genetic drift
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what is Genetic Drift?
chance dictates which alleles are passed on instead of environmental factors determining which individuals survive, breed and pass on their alleles
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How does genetic drift work?
1. individuals within a population show variation in their genotype 2.By chance, the allele for one genotype is passed on to the offspring more often than others 3.number of individuals with this allele increases 4.can lead to evolution.
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When does evolution by genetic drift have a greater effect than natural selection?
in smaller populations where chance has a greater influence. In larger populations any chance variations in allele frequency tend to even out across the whole population
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Give an example of genetic drift?
Human blood groups. it doesn't effect survival or reproduction so isn't due to natural selection
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What is a genetic bottleneck?
An event that causes a big reduction in a population size, leading to a reduction in the gene pool. therefore genetic drift has a bigger influence
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What is a founder effect?
When just a few organisms from a population start a new population and there are only a small number of different alleles in the initial gene pool. as new population is small it is influence more by genetic drift.
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Give an example of the founder effect?
The amish- descended from a small number of swiss who migrated there. population shows very little genetic diversity. they remain isolated from other communities due to religious beliefs so few new alleles have been introduced.
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Card 2

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what is Genetic Drift?

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chance dictates which alleles are passed on instead of environmental factors determining which individuals survive, breed and pass on their alleles

Card 3

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How does genetic drift work?

Back

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Card 4

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When does evolution by genetic drift have a greater effect than natural selection?

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Card 5

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Give an example of genetic drift?

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