Questions tagged [population-genetics]

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

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4
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1answer
695 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
7k views

What are Codominant vs Dominant Genetic Markers?

When talking about types of genetic markers, the adjective "dominant" and "codominant" are often used. I don't fully understand their definitions and found contradicting definitions. Foll and ...
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1answer
767 views

Understanding F-statistics in population genetics

I am reading the classic Weir and Cockerham 1984 paper about $F_{ST}$ estimation. At the beginning (first page, right column), they define 3 statistics. $F$ is the correlation of genes within ...
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1answer
2k 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. $B>$ All $4$ will ...
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3answers
426 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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1answer
75 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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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. ...
6
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1answer
294 views

Variance in Fst in the infinite island model

The most famous result in the study of structured populations come from Sewall Wright. He showed that in an island model, where each subpopulation is of size $N$ and the migration rate is $m$, then ...
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1answer
266 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 ...
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1answer
545 views

ExAC Browser: What does a “dubious variant annotation” mean? [closed]

I am studying a protein in the ExAC browser. However it is flagged with a "LoF flag". What exactly counts as a "dubious" variant in ExAC. I couldn't find any further information neither at the ...
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1answer
990 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 ...
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0answers
149 views

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 ...
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1answer
71 views

Confusion over equations for population's heterozygosity vs. heterozygous individuals

On page 24 of Gillespie's Population Genetics, 2nd ed, an equation for $H$, the probability that two randomly drawn alleles are different by state, is given. $H$ is stated to be similar to the ...
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2answers
187 views

How to define “Quasifixation” in continuous approximation of finite population?

Background Many models including the famous very first models derived by Sir Ronald Fisher in his early career, assume infinite population size. In an infinite population, an allele can rise in ...
2
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1answer
421 views

How to get the average number of pairwise differences among populations?

I have genetic data in .structure and .vcf format (and can easily reach other formats with PGDSpider). The population of interest is structured and I would like to calculate the average number of ...
5
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1answer
244 views

Learn Bioconductor the hard way!

I came to analyzing population genetics data from the background of a theoretician and a computer biologist but not with the standard tools that a bioinformatician (or empiricist in population ...
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1answer
4k views

How to confirm pure-breeding parents

I was reading Genetic Analysis (Sanders, Bowman) and saw the following figure summarizing the 1909 work of Herman Nilsson-Ehle in describing the genetic control of kernel color in wheat: How did ...
4
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2answers
99 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 (...
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1answer
50 views

Reconstituting genomes of archaic tribes of humans

Will it be logically possible for genome studies to reconstitute the genomes of our local human populations as they were 2000 and 4000 years ago? What is the mathematical precision and science for ...
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1answer
69 views

What factors make a sequence evolve non-randomly?

On the wikipedia page about Fay and Wu's H, it talks about a non-randomly evolving sequence may be due to some selection acting or a selective sweep or population expanding/contracting. My questions ...
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1answer
84 views

Is it possible to have a random un-mutation of genes?

According to this article: Gene mutations can be classified in two major ways: Hereditary mutations are inherited from a parent and are present throughout a person’s life in virtually every cell in ...
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1answer
607 views

Why was the study of “Concordance of Monozygotic and Dizygotic twins for traits” designed in this way? [closed]

I am confused by the twin study 'Concordance of Monozygotic and Dizygotic twins for traits.' My questions arose from 3:17-4:17 of the video And this is the related data I have referred I have ...
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1answer
1k 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 ...
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0answers
95 views

Hybridization of an Indo-Aryan ethnic group and a Tibeto-Burmese ethnic group

The state in which I reside houses these two distinct ethnic groups. Physical Traits of the Indo-Aryan group Height:Medium Eyes:does not posses epicanthic fold Nasal bones:is not flat and broad ...
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0answers
114 views

What is the effective population size of a simple two deme metapopulation?

I am confused as to how to compute the effective population size $N_e$ of a theoretical structured population. Let's consider here a simple case study. Imagine a 2-deme metapopulation. Each deme is ...
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2answers
442 views

Are heterozygotes always fitter than homozygotes? Can inbreeding be beneficial?

Inbreeding is mostly not very good because when there is a 'disease' in one allele, the other could/would take over the function. But when you have two of the same genes/alleles, do they, or could ...
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1answer
363 views

What is the percentage of people living in England in 1500 AD whose lineage is still alive?

This sounds a bit random, but it stems from a lecture in statistical genetics which I attended a while ago. We were shown a population lineage graph from which it was clear that most lineages ...
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1answer
90 views

How are the dominance and additive effects reflected in the mean and variance of the offsprings of two individuals with known phenotype?

If I estimated the genetic additive σ2A, genetic dominance σ2D and environmental effect σ2E of a trait in a population, what will be the predicted value of the offsprings of two individuals with known ...
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0answers
60 views

Ecological specialization and relative abundance

I am reading Evolution in Changing Environments by R. Levin but have a hard time. Claim At page 25, Levin says as a conclusion The more efficient a caste at meeting the contingency for which it ...
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1answer
198 views

Statistical genetics: Allele frequencies that follow a Dirichlet distribution

From Foll and Gagiotti (2008) (software BayeScan). They consider a model where several subpopulation are derived from a unique ancestral population. We consider a set of $I$ loci and let $K_i$ be ...
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1answer
131 views

autosomal recessive population numbers

This question is background research for a science fiction / fantasy novel, my knowledge of genetic is very basic. It seems obvious to me that for genetic disorders that are autosomal recessive, if ...
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0answers
49 views

What model of epistasis best fit the reality?

In theoretical population genetics, it is very common to have to assume a model of epistatic interaction. The two most common models are the additive model and the multiplicative model. Additive ...
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1answer
4k views

How would cloning affect conservation of rare species?

Many species are at risk of extinction, and cloning could be seen as a relatively quick method to produce large numbers of members of the species to aid in conservation efforts, especially if the ...
2
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1answer
311 views

Relationship between genetic diversity within and between species

Here is a quote from Wagner (2008) A second line of evidence [against neutralism] comes from the relationship between the mean number of polymorphic differences between alleles within a species, $\...
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0answers
445 views

How does the introduction of clones would affect population genetics? [closed]

Since the ability to clone animals gives another way to preserve species, this could help for the breeding process. It has been noted that with the ability to clone animals, endangered species can ...
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0answers
40 views

Effective population size of a metapopulation structured on a grid

Scenario Consider a rectangular metapopulation consisting of $x \cdot y$ demes, where $x$ is the number of deme horizontally and $y$ is the number of demes vertically. The population size per deme is ...
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1answer
82 views

How big advantage had a trait have to bring to evolve in the human evolution? [closed]

Yes, I've heard that we have evolved from the common ancestor with primates as intesively, as the chimpanzees. Sometimes I read about some enormously complex traits, evolutionary psychologists think ...
1
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1answer
270 views

Hardy-Weinberg equilibrium generalized to add inbreeding (non-random mating)

Background Quoting from Gillespie's book The level of inbreeding is measured by the inbreeding coefficient, $F_I$, which is the probability that two alleles in an individual are identity by ...
3
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0answers
261 views

Population size and genetic drift - What are the evidences?

Wright-Fisher model From the Wright-Fisher model of genetic drift, the random sampling of allele from one generation to the next is taken from a binomial distribution with parameters $2N$ and $p$, ...
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1answer
869 views

Is there a difference between macroevolution and group selection?

I encountered two different attitudes towards macroevolution: The first one included long-term microevolution such as the evolution of Cetacea. The second one included only macroevolution in terms of ...
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1answer
1k views

What's the difference between evolution fitness and reproductive success?

What's the difference biological fitness and reproductive success in the biological terminology?
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1answer
3k views

Why is the probability of fixation of an allele equal to its frequency?

Introduction In a panmictic population, the probability of fixation of an allele at a neutral locus is equal to its frequency at that time. I will refer to this probability of fixation as calculated ...
6
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1answer
112 views

Why is there no symmetry in pigmentation when comparing people north and south of the equator?

If you are at the equator and start moving north, the further you travel, the lighter the skin of the indigenous peoples. Considering that we live on a ball, why do we not find the same traveling ...
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0answers
114 views

Is $F_{ST}$ a probability and a correlation coefficient?

$F_{ST}$ is one of the most famous and most important statistics of all of evolutionary biology. Yet, many people misunderstand it or misuse the classical results from the literature on $F_{ST}$ (...
3
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0answers
323 views

Runs of homozygosity - degree of inbreeding and disease associations

Been reading recently about methods to determine how inbred a particular person is by measuring their "runs of homozygosity." Loosly, these are defined as regions of the genome (typically >1Mb) where ...
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1answer
164 views

Can we say it's hybridisation if it's the same species?

If we mixed two population of the same species into the same environment and then they reproduce together, can we say it's hybridisation? The wikipedia definition is the following: Hybridisation (...
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2answers
203 views

Would a colony with only one male and female collapse?

This is a thought experiment: If we form a population with only a single founder pair, can this population survive? What would happen? Would this inbreeding cause the population to go extinct? Could ...
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1answer
66 views

“Heterozygotic expection” - when heterozygote differs from both homozygotes, but homozygotes are similar

For simple 2-alleles genetic model {a,A} and corresponding quantitative trait Q is typically true that Q(aa)>=Q(aA)>=Q(AA) or conversely Q(AA)>=Q(aA)>=Q(aA). For example, dominance means that Q(...
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1answer
555 views

From STRUCTURE to FSTAT format

From numerical simulations I output a file that is input to STRUCTURE (Hubisz et al. 2009). I now realize that I would need to process my data with FSTAT (Goudet 1995). Both are text files. Is there ...

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