Questions tagged [quantitative-genetics]

Quantitative genetics is the study of inheritance at the phenotypic level.

Filter by
Sorted by
Tagged with
26
votes
1answer
2k views

Additive genetic variance components from LMER in R

I've set up some dummy data in R which makes 40 genetically related lines, they are all siblings within a line so are genetically related by a factor of ½ thus additive genetic variance should be ...
10
votes
2answers
901 views

How does Natural Selection shape Genetic Variation?

Background Importance of the additive genetic variance As stated here, the fundamental theorem of Natural Selection (NS) by Fisher says: The rate of increase in the mean fitness of any organism ...
9
votes
1answer
288 views

Genotype to phenotype map and the G-matrix

Suppose I have a genotype-phenotype map defined by the matrix $\mathbf{Z}$:         The scalars $G,P$ represent the number of genotypes and traits, respectively. ...
8
votes
1answer
152 views

Basic Modelling in Quantitative Genetics

I am pretty bad in thinking quantitative genetics models. I am trying to get some basic understanding of modelling the evolution of a quantitative trait. I am therefore asking for help to analyze a ...
6
votes
1answer
222 views

Recommendations for textbooks on statistical and quantitative genetics, and genetic epidemiology

I'm looking for a textbook on statistical genetics, quantitative genetics, association mapping, and genetic epidemiology. My interests include, but are not limited to, complex trait analysis, and the ...
6
votes
0answers
149 views

Identity by descent among unrelated individuals

I was reading a couple of papers which talk about IBD (Identity by descent) among unrelated individuals (for eg. http://www.pnas.org/content/109/4/1193.long). However they do not seem to clearly ...
5
votes
1answer
254 views

How valid are GO (Gene Ontology) terms?

I'm looking for papers quantifying the validity of ontologies such as GO. I'm relatively new to using annotation terms, and I often hear things like "annotation is messy" and "GO is good but it's ...
5
votes
1answer
305 views

Why estimate linear and full (linear, quadratic, and correlational) selection coefficients separately?

"We then fitted a linear regression including all three life-history traits to estimate the vector of linear selection gradients, β, for each sex (Lande and Arnold 1983). A quadratic regression ...
5
votes
1answer
2k views

What is needed for a G-matrix?

I have been doing a lot of reading on quantitative genetics and the G- (and B-) matrix lately. I get the principle behind performing the analysis now but I am still not sure how to do it. I'd like to ...
5
votes
0answers
54 views

More extreme phenotypes when parents are from diverged populations

In quantitative traits we have many loci affecting a trait. If we took a bunch of parents where all mothers and fathers were of a certain value at the upper end of a trait range, and then looked at ...
4
votes
2answers
164 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
votes
1answer
80 views

Learning tensors for evolutionary or developmental biology

I'm looking for book recommendations on tensor algebra for use in biology. Tensors are being used increasingly in evolutionary biology and developmental biology, it seems. For example, here is an ...
4
votes
1answer
681 views

Epistasis Across Chromosomes and Individuals 'Homozygous for Interactions'

Apologies for any failures in nomenclature. I'm a mathematician who is making a foray into genetics for a masters thesis. Specifically, I'm generating artificial diploid genetic sequence data and ...
4
votes
1answer
298 views

Effect of recombination on the rate of loss of genetic variation

Following up from this question: Does recombination increase the additive genetic variance for fitness? (I'm thinking about the evolution of additive genetic variance and differences between the sex ...
4
votes
1answer
106 views

How many traits can a multivariate breeders equation handle?

The multivariate breeders equation (MBE) by Lande predicts the change in a trait $\Delta \bar z$ (response) as $\Delta \bar z = G \beta$ where $G$ is a genetic variance-covariance matrix and $\beta$...
4
votes
1answer
138 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 ...
4
votes
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. ...
3
votes
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
votes
1answer
73 views

Loss of allelic variation per generation of full-sib mating

If we take a male and female, cross them, and collect one son and one daughter to produce the next generation (and continually do this for many generations) - (full-sib mating design) how much genetic ...
3
votes
0answers
139 views

dominance coefficient, why (1+k)?

I'm trying to get a better understanding of quantitative genetics by reading Lynch and Hill 1986. I'm getting stuck with some notation that's used right at the beginning referring to the mutant and WT ...
3
votes
0answers
156 views

What are the common methods to estimate additive genetic variance?

Additive genetic variance can be estimated in a number of ways, and is a key concept in evolutionary biology and quantitative genetics. What are the typical methods (experimental designs) used to ...
2
votes
1answer
614 views

Additive genetic variance $V_A= 2pqa^2$ … what is $a$?

Reading Falconer and Mackay looking at equation $V_A = 2pqa^2$ (equation 8.5, page 126). I am trying to write a clear explanation of how additive genetic variance is defined and calculated, but I ...
2
votes
1answer
960 views

(Updated question) Problem with Fold-change mean compared to absolute data (in qPCR)

For the problem below I am aware of the statistics involved but just can't get my finger around the following: In biology we use qPCR to measure gene expression or basically number of mRNA copies. It ...
2
votes
1answer
3k 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 ...
2
votes
0answers
50 views

Open access datasets for QTL analysis?

I'm just getting started out learning how to use the QTL package in R studio, and I'm trying to find additional datasets to practice with. I've already worked through the datasets here on the Rqtl ...
2
votes
0answers
190 views

Falconer & Mackay population mean calculation & genotypic values

I am reading chapter 7 of Falconer and Mackay where they give a formula to calculate the population mean as a deviation from the heterozygote genotypic value. As an example, imagine a one locus two ...
2
votes
0answers
203 views

How does geography affect morphological features of the human body

I've seen many times how a person born in one place, goes to another country for a long time, and then they start looking more like the people there, but I never found out how it works. This report ...
1
vote
1answer
56 views

Non-coding DNA correlation with rate of evolution

Non-coding DNA can be helpful in generating useful mutations that can go on to become new features/functionality of an organism. Non-coding DNA also indirectly reduces chances of mutation of useful/...
0
votes
1answer
339 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, ...
0
votes
1answer
98 views

QTL mapping in Drosophila

I have already googled it before but yet unsuccessful in finding the whole topic with intuition. Please help. A guide to an associated book would be greatly valued.
0
votes
1answer
43 views

x-linked recessive inheritance and correlation for males

I was inspired by a discussion in this thread. Wikipedia lists a number of disorders linked to recessive genes on the x-chromosome. One typical example is red-green color blindness. Now wikipedia says ...
0
votes
0answers
83 views

Calculating gene separation -a genetics problem

I am really struggling with genetics. In particular, I have the following question Now I am OK with calculating the separation of genes in centrimorgans when I have data like so: But in the first ...