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Biology Stack Exchange

Questions tagged [population-genetics]

Questions related to the study of the distributions and changes of allele frequency in a population.

362 questions
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Average and lowest degrees of kinship/consanguinity among humans?

I would appreciate insight into the average, median, RMS or any similar measure of relatedness among the current world population - and perhaps something about how rapidly this may be changing. A similar question is how un-related any two humans can…
cTen
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Simulating DNA sequences in R with a given value of $\theta = 4N_{e}\mu$

This might not be the most appropriate site to be asking such a question, but perhaps someone has a solution. My question is: is there an R package or function for simulation of DNA sequences of a given basepair length generated according to a…
compbiostats
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Coalescence time: Is it different for haploids and diploids in population genetics?

I'm trying to model Cyanobacteria cells divergence in 2 populations with mutation rate $-\mu$ and I need to verify my model with a valid theory. I don't have much biology background and all the theories I can find are either valid for haploid…
Sahar Shirani
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Definition of "Effective population size"

Could you explain to me, what is the meaning of "Effective population size ($N_e$)"? I would appreciate an example as well.
Nyctea
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How does Genetic drift and selection affect fixation of an allele?

I want to know how does genetic drift, and selection coefficient (s) together affect the fixation of an allele? For example, if there is a neutral allele (s=0), will only genetic drift cause the fixation or loss of an allele? Similarly, if an allele…
Lauren boomer
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Linkage disequilibrium

I want to know what ranges of value can D' in linkage disequilibrium take? Because I read in my book (An introduction to population genetics by Nielsen and Slatkin) that D' is guaranteed to be between 0 and 1. Whereas at the link provided below, it…
Jane Dow
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If number of children born were spread more evenly among all parents, would our species' genetics have more variability?

Instead of some parents having lots of kids, if the number of kids were spread more evenly to parents having few kids and people who have no children, would it introduce more genetic variability in our species in general?
csp2018
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How to solve these kinds of problems?

16% of people in a population can not roll their tongue .what is the frequency of people which are heterozygous of this character? Please ,any one help and guide me to solve these kind of problems. I tried to solve it using punnet square but i…
Kamal
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Infinite site model and Watterson's Estimator

Why is it that under migration, the watterson's estimator (theta) is upward biased? What does upward bias means? And why do we have downward bias under exponential growth? Lastly, is it only the watterson's estimator whose variance would decrease…
Jane Dow
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How to determine the probability that a mutation is lost / fixed?

I have a question about how to determine the probability that a mutation is lost or fixed after 1 or 2 generations in population genetics. Let's say we have a randomly mixing population, with N diploid individuals (N=5), and there is one mutation…
user27806
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How to tell if/how allele frequencies change (USABO question)

This is question number 34 from the 2014 USABO Open Exam: Black and white mice live on an island and have allele frequencies of B=0.20, b=0.80. On the continent, there is a much large population of mice with allele frequencies B=0.80,b=0.20. Ships…
dhe
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Hardy weinberg equilibrium and Wright Fisher model

Is the hardy weinberg equilibrium derived by using a model similar to the Wright Fisher model, just without assuming genetic drift and finite pop size? Both seem to use the same assumptions except Wright Fisher takes into account finite pop size and…
user25375
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Why is the variance of the Wright-Fisher model not equal p(1-p)/(2N)?

I was looking at the properties of the Binomial probability distribution and it says that the variance is np(1-p). In population genetics, n = 2N. So I would expect to see that the variance is 2Np(1-p). But when looking at the Wright-Fisher model,…
M. Beausoleil
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How to derive the Equilibrium value $\hat F$ equation

In population genetics, there is a relationship between $\hat F$ and $Nm$. $\hat F=\frac{1}{1+4Nm}$ In population genetics textbook, (i.e. Hartl, D. L., and A. G. Clark. 2007. Principles of population genetics. Fourth edition. Sinauer Associates…
M. Beausoleil
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The total numbers of mutations on different branches of gene tree are independent or not?

I was reading Tajima's 1989 paper on his test for neutrality. Tajima, Fumio. "Statistical method for testing the neutral mutation hypothesis by DNA polymorphism." Genetics 123.3 (1989): 585-595. Here is the question: Suppose we have three sequences…
yixianshuiesuan
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