10.2 lecture - (indiscriminate sampling)...

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2 October 2009 The theory is inevitably: - Statistical - Probabilistic - Stochastic Distinguish between the theory and the actual process. Forest: 60/40 dark trees vs. light trees. - Natural selection = discriminate sampling - Drift = indiscriminate. Beatty: how can we distinguish these? Oh, but we can’t. this makes the theory of natural selection unavoidably probabilistic. Suppose that one season, just by bad luck, the dark moths land on light trees more than they do in other seasons, and the light moths are still landing on the same number of light and dark trees as they have in the past. Reason for saying that it’s selection: - The light ones are at their level because of selection. And since the dark moths are even lower, so that decrease in their fitness must be due to selection too. It’s like there’s a moth-eater on all the dark trees. So why is it indiscriminate sampling? - The probability of having <-3SD for dark moths is very very low. Beatty:
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- Can’t distinguish improbable results of NS (discriminate sampling) from random drift
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Unformatted text preview: (indiscriminate sampling) Hardy-Weinberg:-Given: o No selection o No immigration, no emigration o Random mating o No mutations o Infinite population size. Because this is never fulfilled, there is always drift.-Then: (A, p) (a, q) A= allel, p,q= proportions o AA Aa aa o P 2 2pq q 2-Evolution = change in gene/genotype frequencies. This says no evolution because no change in gene frequencies.-If we can measure up the assumptions (givens) then we can product with perfect precision what the gene frequencies and genotype frequencies. p = spq 2 / (1-sq 2 ), s = selection coefficient. Turns out, PNS is the second law of biology. Just like Newtons second law: if theres a force acting on an object, the object experiences acceleration. The first law of Newton is that bodies at equilibrium remain at equilibrium unless acted on by an outside force. The principle of drift is the first principle of biology....
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This note was uploaded on 02/22/2012 for the course HIST 2312 taught by Professor Staff during the Fall '10 term at Texas State.

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10.2 lecture - (indiscriminate sampling)...

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