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Mosquito populations becoming resistant to ddt is a classic example of natural selection acting on the variation within a population.
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So here's the concept of resistance development.
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Resistance development.
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So the few points here are first is variation.
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So let's look into variation.
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So when within a population there is a genetic variation due to mutation and genetic diversity, mutation and genetic diversity.
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Second is selective pressure.
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Selective pressure.
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So when ddt was introduced as an insecticide, when ddt was introduced as an insecticide to control the mosquito population, it acted as a selective pressure.
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It acted as a selective pressure.
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So mosquitoes had, that had genetic variations, mosquitoes that had genetic variations allowing them to tolerate, to tolerate or resist the effects of ddt were more likely to survive the exposure of the insecticide...