MBG 2400 Lecture Notes - Lecture 30: Pleiotropy, Epistasis, Allele

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jadeant325

2 Aug 2017

School

University of Guelph

Department

Molecular Biology and Genetics

Course

MBG 2400

Professor

Andrew Robinson

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Document Summary

Qualitative traits: controlled by 1 or a few loci. Epistasis: alleles at one locus affect expression at another ex. Pleiotropy: one locus, 2+ phenotypes ~ not looking for a phenotypes at a finite level. Count alleles p = p+1/2h q = 1-p. *estimate q from f(aa) by assuming random mating however, if h is available don"t ass-u-me. Large, random mating population without selection, mutation or migration. Unrealistic in most population but in some specific cases it can occur. A large population without selection, migration or mutations can have hw. Sex limited phenotypes are another scenario ~ litter size, milk yield, Detecting carriers: (actual equation not on final_ Single locus selection: fitness, survival, new p and q. 11 (1) 12 (0) 22(0) = 11 has one survived therefore f(1) = 1 if bv (breeding value) use to determine fitness. Measured or scored score phenotypes like calving. Threshold traits: point of change in how we interpret phenotype.

Related Questions

Need help with evolution questions:

1.) A haplotype is best defined as the ________________.

	haploid genotypes of all the gametes produced by a diploid individual

ABO blood type conferred by an individual gamete

genotype of either the paternal or maternal chromosomal complement

multilocus genotype of a chromosome or gamete

2.) Which of the following statements regarding linkage disequilibrium is true?

Exists when D is less than zero, but not when it is greater than zero.

Is reduced by sexual reproduction.

Is increased by crossing-over during meiosis.

Is increased by any random sampling error that happens to create or destroy certain chromosome genotypes but not others.

Is reduced by selection that favors certain combinations of genotypes.

3.) Selection on multilocus genotypes in random-mating populations leads to linkage disequilibrium when _______________.

it reduces mutation rates

it eliminates all haplotypes from the population

it prevents crossing-over during meiosis

some allele combinations confer greater fitness than do others

4.) When two loci are in linkage equilibrium, the allele carried on a chromosome at one locus is independent of the allele carried on the chromosome at another locus. When this is the case, _________________.

allele frequencies will not change over time

the two loci (or, more specifically, their protein products) do not interact

the frequency of each haplotype can be calculated by multiplying the frequency of its two alleles

all possible haplotypes occur at equal frequency

5.) Which of the following accurately characterize(s) Muller's ratchet model for the selective advantage of sexual reproduction?

Drift establishes linkage disequilibrium because multilocus genotypes with few mutations are eliminated by chance events.

In populations without sexual reproduction, deleterious mutations accumulate, eventually imposing such a burden that the population goes extinct.

Sex is favored selectively because it recreates the zero-mutation genotypes lost due to drift.

All of the above correctly characterize Muller's ratchet model for the evolution of sexual reproduction.

6.) The genetic signature of recent positive selection on a locus is _______________.

high frequency and low linkage disequilibrium

low frequency and low linkage disequilibrium

low frequency and high linkage disequilibrium

high frequency and high linkage disequilibrium

7.) Sexual reproduction is advantageous both in changing environments and in constant environments, compared to asexual reproduction.

True

False

8.) Sexual reproduction causes genetic recombination via crossing-over, which combines genotypes from different parents.

True

False

9.) One reason sex may be maintained in natural populations is proposed by the "Red Queen Hypothesis", which states that.....

genotypes created by sex are created by natural selection over and over

recombination creating novel genotypes that can resist infection by parasites

mutation load is reduced by novel adaptive mutations

the ability of sex to fix multiple

MBG 2400 Lecture Notes - Lecture 30: Pleiotropy, Epistasis, Allele

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