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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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5
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1answer
7k views

After how many generations descendant is not more related to ancestor, than to a random individual in an ancestral population?

Descendant of n generation has on average 1/2n DNA of ancestor. (For example children have 1/2 DNA of parents and 1/4 DNA of Grandparents, After 10 Generation 1/1024 DNA and after 100 Generations 1/...
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1answer
211 views

Diffusion approximation to genetic drift

I am reading from the classical textbook Principles of Population Genetics, Hartl and Clark (pdf here). Introduction Let $f(p,x,t)$ denote the distribution of allele frequency $x$ at time $t$ ...
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2answers
668 views

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 ...
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0answers
116 views

How frequent are selective sweeps?

Introduction Selective sweep is the most famous genetic signature of selection. We know of a number of classical examples of selective sweeps, some of them in humans. See the classical example of the ...
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0answers
177 views

How does the population fitness change after a change in mutation rate?

The mean population fitness as given by mutation load theory depends only on the genome-wide mutation rate ($U$). My question is: How many generations is needed to reach a new mutation load ...
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2answers
1k views

Initial population when i count backwards?

My question is dealing with how many ancestors it took to produce me: --> to produce me it took 2 people (my parents) = ($2^1$) people = 2 --> one generation further included = ($2^1 + 2^2$) people = ...
4
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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 ...
4
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1answer
977 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 ...
4
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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 ...
4
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2answers
731 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

Outbreeding depression in humans [duplicate]

Is there any evidence of outbreeding depression in human beings?
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2answers
166 views

Role of drift in evolution of sexually dimorphic traits

Is there a model for predicting how drift can affect the evolution of a sexually dimorphic (SD) trait? I've been trying wrap my mind around this paradoxical question; sexually dimorphic traits evolve ...
4
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1answer
627 views

How could one calculate the gene flow between two populations?

Imagine there are two populations X and Y, and for each population you have the genotypes of each individual in that population (e.g. Aa, AA, aa, etc.), but for multiple loci (e.g. AABb). How could ...
4
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1answer
431 views

Fixation rate at neutral loci

It is a classical result that the expected time for a neutral mutation to occur and to get fixed is $2 N \mu \frac{1}{2N} = \mu$, where $N$ is the population size and $\mu$ is the neutral mutation ...
4
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1answer
43 views

Neisseria meningitidis transformation into a pathogen

I read the wikipedia article about Neisseria meningitidis, and it says that N. meningitidis is a part of the normal nonpathogenic flora in the nasopharynx of up to 5–15% of adults In some cases ...
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 ...
4
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2answers
96 views

Interspecies competition and pathogen

Following my answer to this question, a debate ensued on whether the loss in population of one species (namely red squirrels) due to its lesser resistance to a pathogen brought by a competing species (...
4
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1answer
222 views

Mutation Rate in Multicellular Eukaryotes

I always hear people saying that the mutation rate is around $10^{-6}$ or $10^{-7}$. I don't even know if this number is the mutation rate of genes or of a single nucleotides and I actually (almost) ...
4
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1answer
458 views

Forward versus backward numerical simulations in population genetics

My question is closely related to this post. There are a number of existing platforms to perform numerical individual-based simulation in populations genetics. An almost exhaustive list of such ...
4
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1answer
395 views

Is there a distinction between the fisherian runaway theory and Fisher's sexy son theory?

In many websites/books they are referred to as part of the same process whereby: "runaway" describing that the process continues even after traits become maladaptive the "sexy son theory" explains ...
4
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1answer
647 views

Microsatellites and Minisatellites: Which of these form the basis of DNA fingerprinting?

I'm in a fix. Prepare yourself for a long read We've just learned about minisatellites and microsatellites at class (okay, by "learned", I mean we were told their definitions and essentially ...
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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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102 views

How does the new discovery that mitochondrial dna is inherited from both parents change population genetics and other dates?

This new study seem to have pretty much proven that mtDNA is inherited from both parents. I assume that this would lead to most age estimates of ancient human ...
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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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0answers
55 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 ...
4
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1answer
140 views

The dominance variance on a single locus

I was reading the book "Genetics and Analysis of Quantitative Traits", by Lynch and Walsh. I how the covariance between two individuals with IBD $\Theta$ gets divided into just the additive variance ...
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0answers
63 views

Mechanisms of genotype*sex interactions [closed]

I'm looking for suggestions of the mechanistic level at which genotype*sex interactions can occur. These give different phenotypes from the same genotype dependent on the sex they are expressed in. ...
4
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0answers
1k views

Mutation-Selection-Drift Equilibrium

mutation-selection-drift equilibrium is one of the most important concept of population genetics. I could easily find the calculations for mutation-secltion equilibrium and for mutation-drift ...
4
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2answers
437 views

Is it possible for two people to repopulate earth? [closed]

Today I was wondering this question whether it is possible for two people to repopulate Earth. What if everyone else disappeared, except for two people (man & woman)? Can they repopulate? In ...
3
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2answers
143 views

Conservation Genetics - Book recommendations

Can you please give me some advice for a book in (evolutionary) conservation genetics that offers an in-depth review of the mathematical formulations used in this field. I read the book Evolutionary ...
3
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2answers
740 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 ...
3
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1answer
168 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 ...
3
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1answer
547 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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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 ...
3
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1answer
930 views

How do heredity and regression to the mean work with respect to intelligence?

I am trying to understand the heredity of intelligence between generations in general, and how regression to the mean works in detail in particular. The answer I'm looking for should preferably answer ...
3
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2answers
416 views

Disease causing variants and Hardy-Weinberg Equilibrium

Is it true that many disease causing variants/mutations do not follow Hardy Weinberg Equilibrium? If so, then please elaborate on why this may be true (or not) and provide examples. I am interested ...
3
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1answer
823 views

Ways to distinguish between purifying selection and selective sweep

When looking a population genomic data, regions of low diversity (lower than expected; such as in a region of high recombination) can indicate either purifying selection of deleterious mutations or a ...
3
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1answer
83 views

Altruism in viscous (asexual) populations

The viscosity of a population is the tendency of offspring to remain near their place of birth. Taylor 1992 ("Altruism in viscous populations") provides a model to study how viscosity affects the ...
3
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4answers
1k views

How is it possible for the absolute fitness to be more than 1?

The wikipedia definition of Absolute fitness is "the ratio between the number of individuals with that genotype after selection to those before selection. It is calculated for a single generation and ...
3
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1answer
940 views

Various Genetic Loads and their Definitions

In population genetics, we talk about several types of genetic loads (also called just loads). I am asking for a exhaustive list and a short definition. Here are for example some genetic loads that ...
3
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1answer
322 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. ...
3
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2answers
6k views

How to interpret the breeders equation?

The univariate breeders equation is defined as, $\ R = h^2 s$ where $\ R $ is the response, $\ h^2 $ is the heritability (additive genetic variation), $\ s $ is the selection differential. The ...
3
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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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2answers
4k views

Identity By Descent vs Identity By State

Background The concepts of Identity By Descent (IBD) vs Identity By State (IBS) are central in population genetics, yet I fail to fully wrap my head around the definitions. You can find examples ...
3
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1answer
59 views

What is the distribution of the number of heterozygotes in finite populations?

Consider a bi-allelic locus with alleles A and a. We denote the frequency of the A allele by ...
3
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3answers
3k views

What exactly is extreme heterozygosity and how does it work?

What does the concept of "extreme heterozygosity" mean? I first encountered this concept in "The Drunken Botanist". They describe that when planting a seed from, say, a 'red delicious' which was ...
3
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1answer
995 views

Software to calculate Fst from sequence data

I'm looking for a software to calculate Fst from 3 loci DNA data of individuals from a metapopulation. I don't have any prior on the population structure (have no idea of the number of subpopulations ...
3
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1answer
113 views

Practical Question about Evolution, Population Genetics and Speciation

North American cicada male of the genus Magicicada sing depending on the species at different times of the day and attract the females of the corresponding species. The species are very similar, but ...
3
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1answer
622 views

What is the difference between nucleotide polymorphism (θ) and nucleotide diversity (π)?

In my population genetics book (see reference at bottom) they define them as: Nucleotide polymorphism (θ): proportion of nucleotide sites that are expected to be polymorphic in any sample of size 5 ...