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9 changes: 5 additions & 4 deletions Chapters/Pheno_var.tex
Original file line number Diff line number Diff line change
Expand Up @@ -352,13 +352,13 @@ \subsection{The covariance between relatives}
should be $1$, $0.5$, $0.25$, and $0.125$ respectively in good agreement with
the empirical covariances reported in the title of each graph. The
data were simulated as described in
the caption of Figure \ref{fig:QT1}. The blue line shows $x=y$ and the red
the caption of Figure \ref{fig:QT1}. The dashed red line shows $x=y$ and the solid blue
line shows the best fitting linear regression line. \gitcode{https://github.com/cooplab/popgen-notes/blob/master/Rcode/Quant_gen/QT4.R}}\label{fig:Varying_rellys_phenos}
\end{figure*}

\paragraph{The covariance between identical twins}
Let's first consider the case of a pair of identical twins, monzygotic
twins, from two
(MZ) twins, from two
unrelated parents. Our pair of twins share their maternal and paternal
allele identical by descent ($X_{1M}=X_{2M}$ and $X_{1P}=X_{2P}$). As their maternal and
paternal alleles are not correlated draws from the population,
Expand Down Expand Up @@ -474,7 +474,7 @@ \subsection{The covariance between relatives}
In these figures, we simulate $100$ loci, as described in
the caption of Figure \ref{fig:QT1}.We simulate the genotypes and
phenotypes of the two parents, and then simulate the child's genotype
following mendelian transmission. The blue line shows $x=y$ and the red
following mendelian transmission. The red line shows $x=y$ and the blue
line shows the best fitting linear regression
line. \gitcode{https://github.com/cooplab/popgen-notes/blob/master/Rcode/Quant_gen/QT2.R}
} \label{fig:midpar}
Expand Down Expand Up @@ -588,7 +588,8 @@ \subsection{The covariance between relatives}
\begin{equation}
Cov(X_1,X_2) = r_0 \times 0 + r_1 \frac{1}{2}V_A + r_2 V_A =
2 F_{1,2} V_A \label{additive_covar_general_rellys}
\end{equation}\\
\end{equation}\\
%% Need to define F 1,2 -- EBJ
So under a simple additive model of the genetic basis of a phenotype,
to measure the narrow sense heritability we need to measure the
covariance between pairs of relatives (assuming that we can remove the effect of
Expand Down
16 changes: 8 additions & 8 deletions Chapters/genetic_drift_pop_structure.tex
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Expand Up @@ -209,8 +209,8 @@ \section{A simple model of migration between an island and the mainland.}
\end{question}

\section{Incomplete Lineage Sorting}
Finally we turn to the interaction of
Because it can take a long time for an polymorphism to drift up or down in frequency, multiple population splits may occur during the time an allele is still segregating. This can lead to incongruence between the overall population tree and the information about relationships present at
Finally we turn to the interaction of the coalescent and speciation. %%this is a guess
Because it can take a long time for a polymorphism to drift up or down in frequency, multiple population splits may occur during the time an allele is still segregating. This can lead to incongruence between the overall population tree and the information about relationships present at
individual loci. In Figure \ref{fig:NoILS_poly} and \ref{fig:ILS_poly}
we show a simulation of three populations where the bottom population splits off from the other two first, followed by the subsequent splitting of the the top and the middle populations. We start both simulations with a newly
introduced red allele being polymorphic in the combined ancestral population. The most likely fate of this allele is that it is
Expand Down Expand Up @@ -351,18 +351,18 @@ \section{Incomplete Lineage Sorting}
\begin{center}
\includegraphics[width=\textwidth]{figures/Genetic_drift/ILS/ABBA_BABA_coal.pdf}
\end{center}
\caption{ In both the left and and right trees ILS has occurred between our single lineages sampled from populations A, B, and C. Imagine that population D is a somewhat distant outgroup
such that the lineages from A through C (nearly) always coalesce with each other before any coalesce with D. The small dash on the branch indicates the mutation A$\rightarrow$B occurring, giving rise to the
\caption{ In both the left and and right trees ILS has occurred between our single lineages sampled from populations 1, 2, and 3. Imagine that population 4 is a somewhat distant outgroup
such that the lineages from 1 through 3 (nearly) always coalesce with each other before any coalesce with 4. The small dash on the branch indicates the mutation A$\rightarrow$B occurring, giving rise to the
ABBA or BABA mutational pattern shown at the bottom. } \label{fig:ABBA_BABA}
\end{figure}
%JRI: here and in text you refer to populations ABCD but figure is labelled ``species'' and 1234. I think ABCD for populations and AB for alleles is confusing. I don't know if you need A/B for alleles. Why not use A1A2 or just 1/2 as you have previously? sure you miss the fun mnemonic, but it's clearer for a novice reader

Take a look at Figure \ref{fig:ABBA_BABA}. In both cases the lineages from A and B fail to coalesce in
Take a look at Figure \ref{fig:ABBA_BABA}. In both cases the lineages from 1 and 2 fail to coalesce in
their initial shared ancestral population, and one or the other of them
coalesces with the lineage from C before they coalesce with each other. Each option is equally
coalesces with the lineage from 3 before they coalesce with each other. Each option is equally
likely; therefore the mutational patterns ABBA and BABA are equally likely to occur under ILS. \sidenote{Here we have to assume no structure in the ancestral population.}

However, if gene flow occurs from population C into population B, in addition to ILS the lineage from B can more recently coalesce with the lineage from C, and so we should see more ABBAs than BABAs. To test for this effect of gene flow, we can sample a sequence from each of our 4 populations and count up the number of sites that show the two mutational patterns consistent with the gene-tree discordance $n_{ABBA}$ and
However, if gene flow occurs from population 3 into population 2, in addition to ILS the lineage from 2 can more recently coalesce with the lineage from 3, and so we should see more ABBAs than BABAs. To test for this effect of gene flow, we can sample a sequence from each of our 4 populations and count up the number of sites that show the two mutational patterns consistent with the gene-tree discordance $n_{ABBA}$ and
$n_{BABA}$ and calculate
\begin{equation}
\frac{n_{ABBA}-n_{BABA}}{n_{ABBA}+n_{BABA}}
Expand All @@ -374,4 +374,4 @@ \section{Incomplete Lineage Sorting}

%% Isolation by distance
% https://en.wikipedia.org/wiki/Tobler%27s_first_law_of_geography
% Waldo Tobler, is "everything is related to everything else, but near things are more related than distant things."
% Waldo Tobler, is "everything is related to everything else, but near things are more related than distant things."

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