Drosophila mauritiana inhabits the island of Mauritius in the Indian Ocean. Drosophila simulans, a close relative, is widely distributed throughout the world. What experimental tests would you perform to determine if D. mauritiana and D. simulans are genetically different species?

Dispersed, repetitive sequences such as transposable elements may have played a role in duplicating short regions in a genome. Can you suggest a mechanism?

A geneticist has studied the sequence of a gene in each of three species, A, B, and C. Species A and species B are sister species; species C is more distantly related. The geneticist has calculated the ratio of nonsynonymous (NS) to synonymous (S) nucleotide substitutions in the coding region of the gene in two ways—first, by comparing the gene sequences of species A and C, and second, by comparing the gene sequences of species B and C. The NS:S ratio for the comparison of species B and C is five times greater than it is for the comparison of species A and C. What might this difference in the NS:S ratios suggest?

How might you explain the thousandfold difference in the evolutionary rates of fibrinopeptide and histone $3$?

In the process of catabolism, a substrate _____________.

The coding sequence of the alcohol dehydrogenase (Adh) gene of Drosophila melanogaster consists of $765$ nucleotides ($255$ codons); $192$ of these nucleotides are functionally silent—that is, they can be changed without changing an amino acid in the Adh polypeptide. In a study of genetic variation in the Adh gene, Martin Kreitman observed that $13$ of the $192$ silent nucleotides were polymorphic. If the same level of polymorphisms existed among the nonsilent nucleotides of the Adh gene, how many amino acid polymorphisms would Kreitman have observed in the populations he studied?

If the evolutionary rate of amino acid substitution in a protein is K, what is the average length of time between successive amino acid substitutions in this protein?

If a randomly mating population is segregating n selectively neutral alleles of a gene and each allele has the same frequency, what is the frequency of all the homozygotes in the population?

Ribonuclease, a protein that degrades RNA, is $124$ amino acids long. A comparison between the amino acid sequences of cow and rat ribonucleases reveals $40$ differences. What is the average number of amino acid substitutions that have occurred per site in these two evolutionary lineages? If the cow and the rat lineages diverged from a common ancestor $80$ million years ago, what is the rate of ribonuclease evolution?

During the early evolutionary history of the vertebrates, a primordial globin gene was duplicated to form the $\alpha$- and $\beta$-globin genes. The rate of evolution of the polypeptides encoded by these duplicate genes has been estimated to be about $0.9$ amino acid substitutions per site every billion years. By comparing the human $\alpha$- and $\beta$-globins, the average number of amino acid substitutions per site has been estimated to be $0.800$. From this estimate, calculate when the duplication event that produced the $\alpha$- and $\beta$-globin genes must have occurred.

The heme group in hemoglobin is held in place by histidines in the globin polypeptides. All vertebrate globins possess these histidines. Explain this observation in terms of the Neutral Theory of Molecular Evolution.

What was some of the evidence that led Charles Darwin to argue that species change over time?

The role of a control in an experiment is to ___________.

(a) Write a structural formula for a sulfide having the molecular formula $\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{S}$. (b) What two thiols have the molecular formula $\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{S}$?