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Definition
| When a small group of individuals become isolated or separated from their previous population. When they reestablish a new population the alleles they have may not be representative of the original population. There may be fewer alleles in the founder population, leading to reduced genetic variation. |
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Definition
| When a large population is significantly reduced in numbers, often due to a catastrophic event, resulting in loss of alleles and reduced genetic variation. |
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Definition
| Movement of individuals from one population to another. Therefore the transfer of alleles from one population to another. Gives rise for gene flow between populations. |
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Definition
| In a large population, competition between individuals leads to selection pressures from the environment in which some individuals have traits that are fitter for that particular environment. These individuals are more likely to survive and reproduce, passing those alleles onto their offspring. Thus increasing the frequency of those alleles in the gene pool. |
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Term
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Definition
| The change in the allele frequency in a small population due to random sampling and chance. Eg. Founder effect or bottleneck |
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Definition
| The complete set of unique alleles in a population |
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Definition
| Genes on the same chromosome and are likely to be passed on together. (Unless crossing over occurs) |
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Definition
| Change in the sequence of DNA - gives rise to new alleles |
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Term
| Natural Selection- Stabilising |
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Definition
| Extremes are not favoured average trait becomes higher frequency |
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Term
| Natural Selection- Directional |
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Definition
| One allele/trait favoured over another, the favoured trait increases |
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| Natural Selection- Disruptive |
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Definition
| Extremes favoured, 'average' trait decreases frequency |
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Term
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Definition
| change in allele frequency within gene pool due to random sampling and chance |
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Term
| A small population is created by: |
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Definition
founder effect and bottleneck effect,
these both also lead to genetic drift |
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Term
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Definition
| Change in allele frequency are more significant as a loss or gain of individuals can have a larger impact on overall allele frequencies. |
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Term
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Definition
| changes in allele frequencies are not as significant as there are many individuals to mask the effects of a gain/loss of individuals. |
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Term
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Definition
| Carry the allele but do not express the phenotype |
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Definition
| You are uncertain about the genotype so breed with homozygous recessive and check the ratio. |
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Term
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Definition
| Neither allele dominates and the heretozygote is intermediate in phenotype between the two homozygotes. |
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