Genetic Drift

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Topic 6

• Genetic Drift

Sewall Wright
"Chaos umpire sits, And by decision more embroils
the fray By which he reigns next him high
arbiter Chance governs all" Milton
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Hardy-Weinbergassumes large population size
Reality Populations are finite
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Example of Chance in Allele Segregation
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• Genetic Drift

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TWO TYPES OF GENETIC DRIFT
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1. Bottleneck
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Example
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2. Founder Effect
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Example
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Founder Effect in Island-Hopping Silvereye
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Two Effects of Drift
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Simulated Effect of Population Size on Drift
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Experimental Demonstration of Drift in Fruitflies
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The Story of a Weed Run RampantThe Importance
of Ecological Evolutionary Forces in Biological
Invasions

• Lorne WolfeGeorgia Southern University

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Silene latifolia ( alba) (Caryophyllaceae)

• perennial, dioecious
• native to Europe
• introduced to N. America in 1800s
• 1st reported 1867
• pest plant in Canada USA

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What can explain this genetic change?
1) Drift (founder effect)
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S. latifolia cpDNA FST0.259, Plt0.0001