Describe how populations with substantial genetic differences can form. What is the role of natural selection?

Figure 20.6 illustrates the effect of an ethanol-rich and an ethanol-free environment on the frequency of the Drosophila allele in four populations in a 50-generation laboratory experiment. Population 1 and population 2 were reared for 50 generations in a high-ethanol environment, while control 1 and control 2 populations were reared for 50 generations in a zero-ethanol environment. Describe the effect of each environment on the populations, and state any conclusions you can reach about the role of any of the evolutionary processes in producing these effects.

Biologists have proposed that the use of antibiotics to treat human infectious disease has played a role in the evolution of widespread antibiotic resistance in several bacterial species, including Staphylococcus aureus and the bacteria causing gonorrhea, tuberculosis, and other infectious diseases. Explain how the evolutionary mechanisms mutation and natural selection may have contributed to the development of antibiotic resistance.

Genetic Analysis 20.1 predicts the number of individuals expected to have the blood group genotypes MM, MN, and NN. Perform a chi-square analysis using the number of people observed and expected in each blood-type category, and state whether the sample is in H-W equilibrium (see Section 2.5 for the chi-square formula and table).

In a population of rabbits, f(C₁) = 0.70 and f(C₂) = 0.30. The alleles exhibit an incomplete dominance relationship in which C₁C₁ produces black rabbits, C₁C₂ produces tan-colored rabbits, and C₂C₂ produces rabbits with white fur. If the assumptions of the Hardy–Weinberg principle apply to the rabbit population, what are the expected frequencies of black, tan, and white rabbits?

Sickle cell disease (SCD) is found in numerous populations whose ancestral homes are in the malaria belt of Africa and Asia. SCD is an autosomal recessive disorder that results from homozygosity for a mutant β-globin gene allele. Data on one affected population indicates that approximately 8 in 100 newborn infants have SCD.What are the frequencies of the wild-type (βᴬ) and mutant (βˢ) alleles in this population?

Sickle cell disease (SCD) is found in numerous populations whose ancestral homes are in the malaria belt of Africa and Asia. SCD is an autosomal recessive disorder that results from homozygosity for a mutant β-globin gene allele. Data on one affected population indicates that approximately 8 in 100 newborn infants have SCD.What is the frequency of carriers of SCD in the population?