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I think one would not have a lot of success using a filter to do this, rather using a centrifugal gradient and comparing the fractions to a standard I think would be preferable. Nitrocellulose filters are made with precision but not very astounding accuracy which is the main reason they are commonly used at set sizes (like 0.2 and 0.4 microns) and not often ...


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Short answer Yes that would work in the condition that the trait you select for (size) is heritable. Long answer The kind of selection you would apply is called truncated selection because you fix a limit in size (depends on your filter) under which individuals do not survive and above which individuals survive and reproduce equally. The response to ...


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I think the key work here is 'evolve'. Overall GC/AT ratios change by mutations, whose rate is constant. The probability that given a mutation event that one base will be substituted by another one has been modeled in several ways where the probabilities of different mutations may or may not be the same. Overall the GC content will tend to close to 50%. ...


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Not in general -- there can be linkage disequilibrium among the loci. For instance, say that there are two di-allelic loci, $A/a$ and $B/b$, and that the frequencies of the $A$ and $B$ alleles are both $1/2$ and that they have the same effect on the trait, with no dominance. If all haplotypes in the population are either $Ab$ or $aB$ (with no $AB$ or $ab$ ...


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To derive it, first use that $E[x(1-x)]= E[x-x^2]=E[x]-E[x^2]$ and that $E[x^2]=\text{Var}[x]+E[x]^2$ to rewrite the left-hand side: $$E\left[x_{t+1}(1-x_{t+1})\right] = E\left[x_{t+1}\right](1-E\left[x_{t+1}\right])-\text{Var}\left[x_{t+1}\right].$$ The equation for $p_{ij}$ is just saying that $2Nx_{t+1}$ is binomially distributed with $2N$ trials with ...


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The notation at this site resembles that in your question but preserves the $\frac{x_t}{2N}$ notation for probability of selecting an allele. $$E[\frac{x_{t+1}}{2N})(1 - \frac{x_{t+1}}{2N} )|x_t] = (\frac{x_{t}}{2N})(1 - \frac{x_{t}}{2N}) (1 - \frac{1}{2N}) $$ The expression $(\frac{x_{t}}{2N})(1 - \frac{x_{t}}{2N}) $ is the probability of heterozygosity ...


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This varies by the kind of animal or plant. I think one company would rarely do both. For plants Monsanto comes to mind. And Syngenta. I'm not sure for animals. For beef cattle in the US, this is done by individual ranchers (who may be corporations) that collectively share their genetic data creating a market which can predict the value of a bull. The ...


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Well, the total genetic variance is just, by the definition of the variance, $$ \sigma^2 =\sum_{i,j} f_i f_j (w_{ij}-\bar{w})^2 $$ (using $f_i$ and $w_{ij}$ for frequency and fitness, respectively), and $$\bar{w} = \sum_{i,j} f_i f_j w_{ij}$$ is just the average fitness. You can calculate the additive genetic variance for different loci by simply assuming ...


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To a good first approximation $\overline{\Delta f} = 0$. Where $\overline{\Delta f}$ is the mean change in fitness down to any point or indel mutation. The reasons for this are as follows: In the genome of higher organisms, most of the genome is non-functional ("junk") so most mutations will not have any effect regardless of the change made. A substantial ...


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I don't believe you can produce a general function for this. It will depend on the exact gene and organism you are considering. From a molecular point of view, the vast majority of recessive mutations result from a change producing either a non-functional protein product or a truncated product that is cleaned up by the cell. We can reasonably assume that ...


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[This is purely speculative] Assumptions: impact on fitness is measured by survival chance impact is because of protein coding genes Probability of a mutation at position $i$ $P(m=i\ |\ g)$ where $g$ is the genome with its annotations. Probability that activity of some protein changes by X-fold given mutation at $i^{th}$ position(s) in the genome: ...


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The concept that the environment directly changes DNA and alters the characteristics of the offspring falls under the heading of Lamarkism. In the context of DNA the Lamarkian view would be that the giraffe got its long neck by stretching its neck cells reaching up to tall trees for leaves, which then (somehow) changed the DNA in its gametes and thus ...


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Lewontin's recipe A very nice way to consider natural selection is through the lense of Lewontin's recipe. Evolution of a given trait (tail length for example) through natural selection occurs whenever the three following conditions are met: There is variation for this trait in the population This variation is caused by mutations Part (or the totality) ...



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