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Questions tagged [population-genetics]

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

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1answer
949 views

Question about the consequences of non-random mating and allele frequencies

I just began studying population genetics, and I don't understand something that is written in my lecture: Consequences of non-random mating: More homozygote and less heterozygote ...
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1answer
71 views

Why aren't there more Ash-Red pigeons?

My favorite color pigeon is Ash-Red, but I don't see a lot of them. I figured it must be a recessive phenotype, but when I googled it, I found out it's dominant. So why aren't there more Ash-Red ...
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1answer
166 views

Text Book Recommendation: Organic Evolution

I was wondering if anyone could point me in the direction of any text books on organic evolution? I have recently become interested in the subject and would like to know more. I think an undergrad ...
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2answers
736 views

How is “selection” best defined?

There is natural selection but there is also sexual selection which some regard as a category of natural selection. There is also artificial selection (by humans). The question is, what is a most ...
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1answer
434 views

How to calculate Fst from AMOVA

I calculated an AMOVA from a genind object, with one hierarchical factor. In the table I obtain there are SSD values (for my grouping factor,"Error" and total) and sigma2 values (for my grouping ...
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0answers
60 views

What is Hamilton's rule for multiple generations?

What is Hamilton's rule as it applies to multiple generations? Is it that the lineage success given up by the actor must be exceeded by the lineage success acquired times the relatedness between ...
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0answers
110 views

Isn't heritability more important to genic capture than just genetic variance?

Rowe & Houle (1996) give two criteria for the selection of costly female choice: Condition dependence of sexually selected traits High genetic variance in condition Regarding heritability, ...
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1answer
63 views

How EGDS (endurance genetic distance score) is calculated?

Can anybody please make me understand how EGDS5 has been calculated to 40.8 in this paper at page#31? The formula has been described in this paper but when i tried the same, I am not getting the same ...
4
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1answer
135 views

Polymorphism in number of chromosomes?

The answer to this question, saying that Down Syndrome - a trisomy of human chromosome 21 - is caused by de novo mutation (rather than resulting from standing variation) made me think about ...
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1answer
87 views

Down syndrome in subsaharan populations

What is the rate of occurrences of Down syndrome in subsaharan African populations? Is it the same as in white European populations? An interesting hypothesis came to my mind: Could it be that Down ...
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1answer
69 views

How can one calculate “probability of possessing a ‘perfect’ profile” from “typical optimal genotype frequencies”?

Can anyone please explain how the "Probability of possessing a ‘perfect’ profile" was calculated from "typical frequency of optimal genotype" in Table 1 in this paper? Paper link here
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0answers
392 views

Can the value of heritability be greater than 1?

Heritability defined as genetic variance divided by total variance seems to be bounded between 0 and 1. However, I see a way of calculating heritability on this page (http://www.radford.edu/~rsheehy/...
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1answer
33 views

How would you model the evolution of two genotypes across generations?

Say you have a genotype A that produces x offspring and another genotype B that produces y offspring, where x>y. These x offspring are of genotype A but with modest differences in fitness due to ...
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1answer
1k views

Dominance coefficient

I am trying to understand the meaning of the dominance coefficient. I'll be more specific to what I don't understand, in a moment. Let $A_{11}$, $A_{12}$ and $A_{22}$ be genotypes with fitnesses $1$, $...
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1answer
91 views

Heritability in population genetics

What is the difference between narrow sense heritability and broad sense heritability? Does heritability in the broad sense refer to the degree of genetic determination? Heritability in the narrow ...
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0answers
91 views

Why does my simulation not support the idea that inbreeding is bad?

After reading this post, I wrote some code to simulate inbreeding. We have a population of $N$ creatures. Each creature has two genes, which come in two forms: recessive (a) and dominant (A). The ...
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4answers
3k views

What are the consequences of inbreeding?

Inbreeding increases the risk of getting two identical recessive genes, alleles, that cause a disease which wouldn't have been activated with mixed genes. That's how I understand it anyway. But I ...
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1answer
976 views

Assumptions of Hardy-Weinberg rule

The post Solving Hardy Weinberg problems offers an easy explanation of Hardy-Weinberg rule. The current top answer explicitly does not talk about the assumptions of Hardy-Weinberg. A model makes sense ...
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0answers
55 views

How do I solve this problem related to specificity and sensitivity?

Consider an autosomal recessive disease with an incidence of 1/10,000 in the general population of 100,000. Your best friend comes to you very upset because he has just taken a screening test for this ...
4
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0answers
54 views

How Can Homosexuality be Genetic? [duplicate]

I hold no strong opinions towards homosexuality one way or the other; I'll personally refrain, but don't apply my personal tastes to the rest of the world. I remember seeing some articles a while ...
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0answers
255 views

Example of code with pypgen (python)

I have a VCF file and wish to calculate a few indices of population divergence over a sliding window. I consider using pypgen but the documentation is currently very limited. Can you please give me ...
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1answer
612 views

On the selection coefficient

I'm reading Williams' Adaptation and Natural Selection: A Critique of Some Current Evolutionary Thought. In this book the author talks about selection coefficients which, if I understand it ...
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0answers
1k views

Are epicanthic folds a dominant trait?

My state (Tripura) originally had a mostly mongoloid-feature-possessing population (ethnic group: Tripuri). Recently a large number of non-mongoloid people (ethnic group: Bengali) have migrated to ...
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1answer
176 views

Hardy Weinberg principle

The principle is that sum total of all allelic frequencies is 1. Individual frequencies for example can be named p,q.In a diploid cell , p and q represent the frequency of allele A and a respectively ...
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2answers
91 views

Is this formula describing the loss of unfixed genes from a population accurate?

In the 1954 science fiction novel Search the Sky by Frederick Pohl and Cyril M. Kornbluth, a formula is featured that "quantitatively describes the loss of unfixed genes from a population". $$L_T=L_0 ...
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0answers
62 views

Need clarification on HKA test

I understand that HKA test tests for neutrality. And under neutrality we say that "ratio of segregating sites with species (S1) and fixed differences between locus (F1)" (S1/F2) at one locus is equal ...
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1answer
205 views

How migration creates Linkage Disquilibrium

I want to know how admixture and migration creates linkage disequilibrium? I am reading about it but I really don't quite get it.
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0answers
55 views

Need clarification on Coalescent with Recombination

I've been reading about recombination with coalescent. The link to that file is as follows: http://www.stats.ox.ac.uk/__data/assets/pdf_file/0008/4688/Reading_for_Recombination.pdf I get the part ...
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1answer
92 views

Is inbreeding really efficient at producing homozygosity?

Inbreeding results in homozygosity. I've come across this concept many times and there's a question that comes to my mind every time I read it. Let us suppose the character we are trying to ...
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0answers
233 views

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 ...
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1answer
80 views

Does anyone know of a study supporting predictions #2 or #9 of the Extended Evolutionary Synthesis?

Regarding the 12 predictions made by the Extended Evolutionary Synthesis (http://extendedevolutionarysynthesis.com/about-ees/), does anyone know of a study that supports #2 or #9? It seems like #1, ...
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2answers
730 views

How to distinguish between a genetic bottleneck and directional selection?

Genetic bottlenecks and directional selection should have relatively similar genetic signals: reduced heterozygosity and greater genetic divergence (Fst?) in contemporary populations compared to the ...
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1answer
1k views

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 ...
3
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1answer
67 views

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 ...
3
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1answer
176 views

How to predict future generations from heritability

The heritability of human intelligence is estimated to be around 0.5. There are of course various estimates, some lower, some higher. But let's work with this value of 0.5 for the moment. I wanted ...
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0answers
217 views

Genotype frequencies and fitness values in haploid population with clonal growth

I found a small problem, and I am not sure at all about my answers. If someone could correct it, that would be awesome. Consider a heterogeneous population with the following genotype frequencies ...
2
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1answer
2k views

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 ...
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0answers
100 views

Interpretation of table on analysis of genetic diversity between groups

I am very confused about how to interpret Table 8.3 in Smith's Evolutionary Genetics. Is the GST in the table the same as the G,ST (with the comma), which is defined (pg. 156; Box 8.3) as "the ...
3
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1answer
321 views

Lethal gene and population genetics

In the European population, about 1 in 2500 people suffers from Cystic Fibrosis, a genetically determined (descared), autosomal disease. Healthy parents have a child suffering from Cystic Fibrosis. ...
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1answer
402 views

How to determine whether changes of an allele's frequency are due to genetic drift or selection?

Given that both natural/artifical selection and genetic drift are evolutionary mechanisms that influence how allele frequencies shift in a population: Are there ways to determine whether a frequency ...
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1answer
347 views

Does covariance and phenotypic variance have to be for the same trait to calculate narrow-sense heritability?

I'm working on a problem where I'm given that the phenotypic variance of the parent, $p$, for trait $A$ is $175.2$ and the phenotypic variance of the offspring, $o$, for trait $A$ is $146.1$. However, ...
2
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1answer
456 views

What is a typical value of the selection coefficient s?

I am trying to gain an understanding of the real world effects of natural selection from the equations, especially comparing it with drift. However I have been unable to find any examples which give ...
2
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2answers
83 views

Mixed-mating plants: is the number of mixed mating plants supposed to be trivial?

I am referring to Winn et al. 2011 Last sentence of the first paragraph is Although sampling bias against both selfing and highly outcrossing species may inflate the frequency of mixed-mating ...
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1answer
1k views

Probability of number of boys and girls being born on a single day [closed]

I am new to genetics, I have the following question at hand : If four babies are born on a single day, what are the chances that $A>$ Number of boys and girls will be equal. $B>$ ...
3
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1answer
542 views

Genotypes in diploid/haploid cells under mitotic/meotic cell divisions

I am new to genetics , and am stuck with the following question at hand: If $2$ cells with genotypes $(A/a)$ and $(A/a,B/b)$ undergo mitotic and meotic cell divisions respectively, what will be the ...
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1answer
74 views

Fst Differences Between Mature Trees and Seeds

For a single co-dominant locus in two populations of blue oak, I am given genotype frequency data (genotypes are AA, AB, BB) for adult trees (at least 150 years old) in both populations (pop 1 and pop ...
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3answers
1k views

Allele frequency question

You are heterozygous at locus A. Both of your alleles, A1 and A2, have a 10% allele frequency in the population. If you are one of 22 people in a room, how many people do you expect to share a locus A ...
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3answers
399 views

Is the variance of a trait related to its rate of evolution?

Posed with a question that has me stuck: Is increased variance of a phenotypic trait in a population associated with slower evolution of that trait? I have to either 'disagree or agree' and argue ...
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0answers
38 views

Method to estimate age of a variant from genotype data

I will obtain array genotype data from approximately 60 related individuals who all share a rare pathogenic variant, which is at such a high frequency in the enlarged family due to a founder effect. ...
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1answer
251 views

Summary statistic that can distinguish between migration from pop2 to pop1 vs. pop1 to pop2

Given two sister populations that diverged some time ago, say pop2 migrates to pop1 and breeds there, giving offspring with sequence segments similar to those from pop1 but not in pop2. There are ...