DNA and protein molecules are “documents of evolutionary history.” Why aren’t complex carbohydrate molecules such as starch, cellulose, and glycogen considered “documents of evolutionary history”?

In a survey of electrophoretically detectable genetic variation in the alcohol dehydrogenase gene of Drosophila melanogaster, a researcher found two forms, denoted F (fast) and S (slow) in a population; $32$ individuals were homozygous for the F allele of the gene, $22$ were homozygous for the S allele, and $46$ were heterozygous for the F and S alleles. Are the observed frequencies of the three genotypes consistent with the assumption that the population is in Hardy–Weinberg equilibrium?

Theodosius Dobzahnsky and his collaborators studied chromosomal polymorphisms in Drosophila pseudoobscura and its sister species in the western United States. In one study of polymorphisms in chromosome III of D. pseudoobscura sampled from populations at different locations in the Yosemite region of the Sierra Nevada, Dobzhansky ($1948$, Genetics $33$: $158–176$) recorded the following frequencies of the Standard (ST) banding pattern:

$$\begin{array}{lcc} \text { Location } & \text { Frequency ST } & \text { Elevation (in feet) } \\ \hline \text { Jacksonville } & 0.46 & 850 \\ \text { Lost Claim } & 0.41 & 3,000 \\ \text { Mather } & 0.32 & 4,600 \\ \text { Aspen } & 0.26 & 6,200 \\ \text { Porcupine } & 0.14 & 8,000 \\ \text { Tuolumne } & 0.11 & 8,600 \\ \text { Timberline } & 0.10 & 9,900 \\ \text { Lyell Base } & 0.10 & 10,500 \end{array}$$

What is interesting about these data?

Assuming that mating is random with respect to the blood type, predict the frequencies of the three genotypes of the Duffy blood-type locus in a South African and an English population

A segment of DNA in an individual may differ at several nucleotide positions from a corresponding DNA segment in another individual. For instance, one individual may have the sequence $\dotsb$A $\dotsb$ G $\dotsb$ C $\dotsb$ and another individual may have the sequence $\dotsb$ T $\dotsb$ A $\dotsb$ A $\dotsb$ . These two DNA segments differ in three nucleotide positions.Because the nucleotides within each segment are tightly linked, they will tend to be inherited together as a unit, that is, without being scrambled by recombination. We call such heritable units DNA haplotypes. Through sampling and DNA sequencing, researchers can determine which DNA haplotypes are present in a particular population. When this kind of analysis is performed on human populations by sequencing, for example, a segment of mitochondrial DNA, it is found that samples from Africa exhibit more haplotype diversity than samples from other continents. What does this observation tell us about human evolution?

The prune gene (symbol pn) is X-linked in Drosophilavmelanogaster. Mutant alleles of this gene cause the eyes to be brown instead of red. A dominant mutant allele of another gene located on a large autosome causes hemizygous or homozygous pn flies to die; this dominant mutant allele is therefore called Killer of prune (symbol Kpn). How could mutants such as these play a role in the evolution of reproductive isolation between populations?

Distinguish between allopatric and sympatric modes of speciation.

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?

A sample for which each member of a population has an equal chance of being selected is a(n) _______ sample.

Exon shuffling is a mechanism that combines exons from different sources into a coherent sequence that can encode a composite protein—one that contains peptides from each of the contributing exons. Alternate splicing is a mechanism that allows exons to be deleted during the expression of a gene; the mRNAs produced by alternate splicing may encode different, but related, polypeptides. What bearing do these two mechanisms have on the number of genes in a eukaryotic genome? Do these mechanisms help to explain why the gene number in the nematode Caenorabditis elegans is not too different from the gene number in Homo sapiens?

The achoo syndrome (sneezing in response to bright light) and trembling chin (triggered by anxiety) are both dominant traits in humans. a. What is the probability that the first child of parents who are heterozygous for both the achoo gene and trembling chin will have achoo syndrome but lack the trembling chin? b. What is the probability that the first child will not have achoo syndrome or trembling chin?

Darwin stressed that species evolve by natural selection. What was the main gap in his theory?

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?