Florida International University

PCB evolution

Chapter 10

1)In genetic terms, linkage is defined as:

1. the nonrandom association of genes in different loci.
2. the random association of alleles in different loci.
3. the nonrandom association of alleles in different loci.
4. the nonrandom association of haplotypes in different loci.

2. Two loci are in linkage disequilibrium when:

1. the genotype of a chromosome at one locus is independent of its genotype at the other locus.

2. two populations have different allelic frequencies.
3. the genotype of a chromosome at one locus is dependent of its genotype at the other locus.
4. there is a random association between a chromosome’s genotype at one locus and its genotype at the other locus.

3. Among other conditions fulfilled by a population in linkage equilibrium, chromosome frequencies will be determined by                                                  .

1. the product of the allelic frequencies at different chromosomes.
2. the product of allelic frequencies at different loci.
3. the product of haplotypic frequencies at different loci.
4. the product of haplotypic frequencies at different chromosomes.

4. The coefficient of linkage disequilibrium D is described by the expression                          , where

g represents               .

1. (g_AB g_aB) - (g_ab g_Ab) / haplotypic frequencies.
2. (g_AB g_ab) - (g_Ab g_aB) / haplotypic frequencies.
3. (g_AB g_ab) + (g_Ab g_aB) / haplotypic frequencies.
4. (g_AB g_ab) - (g_Ab g_aB) / allelic frequencies.

5. The absolute value of the coefficient of linkage disequilibrium (D) is                           correlated with the                                 rate in the population.

1. directly/recombination.
2. inversely/mutation.
3. inversely/recombination.
4. directly/mutation.

6. Different evolutionary forces can produce linkage disequilibrium in populations, most notably  .

1. population admixture and genetic drift.
2. selection and genetic drift.
3. selection and population admixture.
4. population admixture, selection and genetic drift.

7. While genetic distances between loci are estimated on the basis of                     , physical distances between loci are measured in                                     .

1. base pairs/recombination frequencies.
2. recombination frequencies/centimorgans.
3. kilobases/centimorgans.
4. recombination frequencies/base pairs.

8. The overall amount of linkage disequilibrium will be gradually reduced across generations in the presence of                                              .

1. unequal crossover and inbreeding.
2. genetic recombination and outbreeding.
3. genetic recombination and inbreeding.
4. selection and random genetic drift.

9. Just because two loci are                  this does not mean that they will be                  .

1. linked/in linkage disequilibrium.
2. linked/in linkage equilibrium.
3. all answers are true.
4. nonrandomly associated/linkage equilibrium.

10. In the phenomenon known as genetic hitchhiking                   .

1. frequencies of apparently neutral or mildly deleterious alleles will change because of random association with an allele subject to selection in another locus.
2. frequencies of harmful alleles will change because of random association with an allele subject to selection in another locus.
3. frequencies of harmful alleles will change because of linkage with an allele not subject to selection in another locus.
4. frequencies of apparently neutral or mildly deleterious alleles will change because of linkage with an allele subject to selection in another locus.

More questions

1. 1. What will be the outcome of selection against a recessive lethal deleterious allele?
   2. Human beings, as we know them, developed from earlier species of animals
   3. Can random changes in the genetic material lead to evolutionary order?
   4. Does any of the species at tips of the branches in an evolutionary tree descend from any of the other?