Advanced Quantitative Genetics (Lecture 12)

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Questions and Answers

What is the primary purpose of QTL mapping in quantitative genetics?

To assess the degree of phenotypic plasticity in a population.
To identify specific genomic regions associated with quantitative traits. (correct)
To quantify the total genetic variance within a population.
To measure the rate of recombination between two genetic loci.

How does narrow-sense heritability (h²) relate to the resemblance between parents and offspring?

h² quantifies the total genetic variation, regardless of whether it's inherited.
A high h² suggests offspring will strongly resemble their parents due to additive genetic effects. (correct)
h² only applies to traits with no environmental influence.
A high h² indicates a weak resemblance because environmental factors dominate.

What is the significance of linkage disequilibrium (LD) in genetic studies?

LD signifies a non-random association of alleles, useful for tracing inheritance patterns and evolutionary history. (correct)
LD indicates alleles at different loci assort independently, simplifying genetic mapping.
LD is only relevant in populations under Hardy-Weinberg equilibrium.
LD represents the random association of alleles, suggesting no evolutionary relationship.

In the context of quantitative genetics, what does phenotypic plasticity refer to?

The ability of a single genotype to produce different phenotypes across varying environments. (C) Signup and view all the answers

What is the main reason that physically close genes on a chromosome tend to recombine less frequently than genes that are far apart?

Crossing over events are less likely to occur between closely positioned genes. (A) Signup and view all the answers

How does chromosomal inversion contribute to maintaining adaptive gene combinations, particularly in the context of coastal vs. inland adaptations?

Inversions suppress recombination within the inverted region, preserving specific gene combinations. (D) Signup and view all the answers

Why can broad-sense heritability (H²) be a limited measure of heritability?

It lumps all genetic variance into one value, not distinguishing between different genetic effects. (A) Signup and view all the answers

How does selection differential (S) relate to the response to selection (R) and narrow-sense heritability (h²)?

R = h²S, indicating response is the product of heritability and selection differential. (D) Signup and view all the answers

What does a 'supergene' refer to in the context of linked gene complexes?

A suite of genes that tend to be inherited together because they are closely linked. (C) Signup and view all the answers

What is the significance of analyzing association between markers and phenotypes in QTL mapping?

It helps locate regions where marker patterns correlate with trait values, indicating QTLs. (A) Signup and view all the answers

How do 'crossing reaction norms' differ from 'parallel reaction norms' in the context of genotype-by-environment interactions?

Crossing reaction norms indicate genotypes respond differently, while parallel norms indicate similar responses. (A) Signup and view all the answers

In the mouse coat color adaptation case study, what role does epistasis play between the Agouti and MC1R genes?

Epistasis involves one gene masking the effect of another. (D) Signup and view all the answers

According to the lectures, how do coastal and inland populations of yellow monkey flowers differ in their adaptive traits?

Coastal populations typically exhibit traits such as being perennial, late flowering, and having large flowers and thick stems. (C) Signup and view all the answers

According to the lecture, what is the formula for broad-sense heritability (H²)?

$H^2 = VG/VP$ (A) Signup and view all the answers

Which of the following statements accurately describes the relationship between linkage equilibrium and linkage?

When linkage is in equilibrium, there is no linkage between genes. (B) Signup and view all the answers

According to the lecture, what is G x E interaction?

The change in the rank order of performance of genotypes across different environments. (B) Signup and view all the answers

What distinguishes recombinant inbred lines from naturally occurring populations in genetic studies?

Recombinant inbred lines are created through crossing and inbreeding to create genetically identical lines. (D) Signup and view all the answers

How does the melanization of Daphnia melanica demonstrate phenotypic plasticity in response to environmental conditions?

Melanization increases in high UV environments when predators are absent due to the cost of visibility. (A) Signup and view all the answers

What information do linkage maps provide in the context of quantitative genetics?

The degree of linkage disequilibrium between genomic regions. (C) Signup and view all the answers

In fruit fly larvae, how do the 'rovers' and 'sitters' demonstrate genetic and behavioral variation?

Rovers and sitters exhibit distinct foraging behaviors controlled by genetic differences. (D) Signup and view all the answers

What is the effect of inversions on recombination rate?

Inversions decrease recombination rates. (A) Signup and view all the answers

What is the genetic difference between minor and major workers in developmental polyphenism in ants?

Minor and major workers develop from the same genotype. (B) Signup and view all the answers

Leaf size responses to light levels vary among plant genotypes. What type of interaction is this an example of?

G x E interaction. (D) Signup and view all the answers

Which of the following formulas represents the relationship between variance in phenotype, genotype effect, environment effect, and G x E interaction?

Variance in phenotype = genotype effect + environment effect + G x E interaction. (C) Signup and view all the answers

Which of the following is the best way to explain the difference between broad-sense and narrow-sense heritability?

Broad-sense heritability includes all the genetic effects whereas narrow-sense only includes additive genetic effects. (B) Signup and view all the answers

If 'S' denotes selection differential, what does 'S' represent?

The difference in the mean trait value between the selected individuals and the entire population. (A) Signup and view all the answers

How does knowledge of linkage disequilibrium aid in understanding the genetic basis of diseases?

By helping to locate disease-associated variants through marker alleles closely linked to disease genes. (B) Signup and view all the answers

In QTL mapping, what is the function of genetic markers across the genome?

Genetic markers serve as signposts to track genomic regions associated with quantitative traits. (A) Signup and view all the answers

According to the lectures, which Monkey flower species were tested for QTL mapping of floral traits?

Mimulus (A) Signup and view all the answers

What question could you ask to determine how chromosomal inversions maintain adaptive gene combinations?

How do chromosomal inversions maintain adaptive gene combinations? (B) Signup and view all the answers

Why might some traits be affected by G x E interactions?

Different patterns of plasticity evolve based on selection pressures in variable environments. (D) Signup and view all the answers

How does physical proximity of genes on chromosomes affect recombination frequency?

Physically close genes decrease recombination frequency. (A) Signup and view all the answers

What is the first step in QTL mapping?

Create divergent populations through selection. (C) Signup and view all the answers

If offshore sticklebacks have bony plates and freshwater sticklebacks do not, which of the following is true of the EDA gene?

The EDA gene encodes for the lateral plates but other genes are involved. (B) Signup and view all the answers

Flashcards

Topic/Subject

Advanced concepts in quantitative genetics, including linkage, QTL mapping, and phenotypic plasticity.

Variance

Statistical measure of the dispersion of trait values about their mean.