Disruptive Trait The figure above shows disruptive selection. The trait distribution changes from the black line to the green (lighter) line. During disruptive selection as shown above The standard deviation of the trait distribution decreases The standard deviation of the trait distribution increases The mean value of the trait distribution is selected for OThe mean value of the trait distribution in the population becomes smaller O The mean value of the trait distribution in the population becomes larger Frequency

Disruptive Trait The figure above shows disruptive selection. The trait distribution changes from the black line to the green (lighter) line. During disruptive selection as shown above The standard deviation of the trait distribution decreases The standard deviation of the trait distribution increases The mean value of the trait distribution is selected for OThe mean value of the trait distribution in the population becomes smaller O The mean value of the trait distribution in the population becomes larger Frequency

Biology (MindTap Course List)

11th Edition

ISBN:9781337392938

Author:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Publisher:Eldra Solomon, Charles Martin, Diana W. Martin, Linda R. Berg

Chapter19: Evolutionary Change In Populations

Section: Chapter Questions

Problem 3TYU: The MN blood group is of interest to population geneticists because (a) people with genotype MN...

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Small population size causes genetic drift because ofchance sampling of different alleles from one generation to the next. We can predict how much geneticdrift occurs for a given population size using binomialsampling statistics. With a population of size N, wecan estimate that 95% of the time the allele frequency(p) in the next generation will be withinthe confidence interval of p ± 1.96 (√p(1 − p)2N ),where p(1 − p)2Nis an estimate of the statistical variancein allele frequencies from one generation to the nextwith random sampling of 2N alleles each generation. a. What is the confidence interval for p = 0.5 whenN = 100,000?b. What is the confidence interval for p = 0.5 whenN = 10?c. How are the results in parts (a) and (b) related tothe consequences of a population bottleneck?
A botanist studying water lilies in an isolated pond observedthree leaf shapes in the population: round, arrowhead, and scalloped.Marker analysis of DNA from 125 individuals showed theround-leaf plants to be homozygous for allele r1, while the plantswith arrowhead leaves were homozygous for a different allele atthe same locus, r2. Plants with scalloped leaves showed DNA profileswith both the r1 and r2 alleles. Frequency of the r1 allele wasestimated at 0.81. If the botanist counted 20 plants with scallopedleaves in the pond, what is the inbreeding coefficient F forthis population?
Figure 19-9 shows the trait distributions before and aftera cycle of artificial selection. Does the variance of thetrait appear to have changed as a result of selection?Explain.
Two traits with similar phenotypic variance exist in apopulation. One trait has two major genes and sixminor loci that influence the phenotypic value, andthe second trait has 12 minor loci and no major genesaffecting the phenotypic value. Does this informationtell you which trait you should expect to respondmost consistently to selection? Explain why it doesor does not.
Which of the following statements would be true of ahuman trait that has high heritability in a populationof one country?a. The phenotypic difference within monozygotic twinpairs would be about the same as the phenotypic differences among members of dizygotic twin pairs.b. Very little phenotypic variation exists betweenmonozygotic twins but high variability exists between dizygotic twins.c. The trait would have the same heritability in a population of another country
The MN blood group is of interest to population geneticists because (a) people with genotype MN cannot receive blood transfusions from either MM or NN people (b) the MM, MN, and NN genotype frequencies can be observed directly and compared with calculated expected frequencies (c) the M allele is dominant to the N allele (d) people with the MN genotype exhibit frequency-dependent selection (e) people with the MN genotype exhibit heterozygote advantage
How Can We Measure Allele Frequencies in Populations? The MN blood group is a single-gene, two-allele system in which each allele is codominant. Why are such codominant alleles ideal for studies of allele frequencies in a population?
In a population that is in Hardy-Weinberg equilibrium, 37% of the individuals exhibit the recessive trait (ss). a) What is the frequency of the dominant allele (S) in the population? b) What percent of the population possesses the dominant allele (S)?
You are a rabbit breeder, and you decide that you want rabbits with long fur. Thephenotypic variance of fur length is 4 cm2. The covariance of fur length between betweenfull sibs is 1 cm2. The mean fur length in the initial population is 3 cm. You choose to breedthe top 1/3 of the population with the longest fur, and their mean fur length is 5 cm. Assumethat the covariance between sibs is due to only additive genetic variance.a) What is the narrow sense heritability (h^2 ) of fur length?b) What do you expect the mean fur length to be in the progeny of rabbits you breed?c) How many generations of this selection regime will it take for the mean fur length of thepopulation to be 10 cm? (Assume heritability and additive genetic variance remainunchanged throughout this process.)
What is a normal distribution? Discuss this curve with regard toquantitative traits within a population. What is the relationshipbetween the standard deviation and the normal distribution?
Different species of crickets have distinct songs, andthey use these songs for mate recognition. Researcherscrossed two species of Hawaiian crickets (Laupala paranigra and L. kohalensis) whose songs are distinguishedby pulse rate (the number of pulses per second; Shaw etal., Molecular Ecology 16, 2007, 2879–2892.) Then, theymapped QTL in the F2 population derived from thiscross. Six autosomal QTL were detected. The mean traitvalues (pulses per second) at the three genotypic classesin the F2 for each QTL are shown in the table below,where P indicates the L. paranigra allele and K indicatesthe L. kohalensis allele.a. Calculate the additive (A) and dominance (D) effectsand the D/A ratio for each of the six QTL.b. Which of these QTL shows the greatest amount ofdominance?c. Which of these has the largest additive effect?d. The mean pulse rate for L. kohalensis is 3.72, and it is0.71 for L. paranigra. Do all six QTL act in the expecteddirection with the L. kohalensis allele conferring a…
Two populations of snakes are separated by a river. The snakescross the river only on rare occasions. The snakes in the two populationslook very similar to each other, except that the members ofthe population on the eastern bank of the river have a yellow spoton the top of their head, whereas the members of the western populationhave an orange spot on the top of their head. Discuss twoexperimental methods that you might use to determine whether thetwo populations are members of the same species or members ofdifferent ones.