Exam 24: Evolution by Natural Selection

After the drought of 1977,researchers hypothesized that on Daphne Major,medium ground finches with large,deep beaks survived better than those with smaller beaks did because they could more easily crack and eat the tough Tribulus cistoides fruits.If this hypothesis is true,what would you expect to observe if a population of these medium ground finches colonizes a nearby island where Tribulus cistoides is the primary available food in all years? Assume that (1)even the survivors of the 1977 drought sometimes had difficulty cracking the tough T.cistoides fruits and would eat other seeds when offered a choice;and (2)food availability is the primary limit on finch fitness on this new island.

Which of the following is a fitness trade-off?

Your text discusses the evolution of antibiotic-resistant M.tuberculosis bacteria in a patient.Researchers discovered that the strain of M.tuberculosis taken from the dead patient has a point mutation in the rpoB gene that codes for part of the RNA polymerase enzyme.This mutant form of RNA polymerase does not normally function as well as the more common form,but a commonly used antibiotic called rifampin does not affect the mutant rpoB.A researcher places M.tuberculosis isolated from the patient a year before death (no rpoB mutation)in cell cultures with M.tuberculosis isolated from the dead patient (with rpoB mutation).Half the cell cultures contain just standard nutrients,and the other cell cultures contain rifampin in addition to the standard nutrients.After many cell generations,the researcher finds that _____.(choose one)

The same basic internal organs (kidneys,stomach,heart,lungs)are found in frogs,birds,snakes,and rodents.This is primarily an example of _____.

Use the following information when answering the corresponding question(s). The following question(s)are based on information from Frank M.Frey,"Opposing Natural Selection from Herbivores and Pathogens May Maintain Floral-Color Variation in Claytonia virginica (Portulacaceae)," Evolution 58(11),2004: 2426-37. -Claytonia virginica is a woodland spring herb with flowers that vary from white to pale pink to bright pink.This plant is primarily pollinated by a bee that prefers pink flowers to white flowers.Claytonia with pink flowers have greater relative fruit set than Claytonia with white flowers.Nevertheless,the percentage of different flower colors remains stable in the study population from year to year.Which of these statements might explain this observation?

If two organisms show a developmental homology,you would also definitely expect them to _____.

Cotton-topped tamarins are small primates with tufts of long white hair on their heads.While studying these creatures,you notice that males with longer hair get more opportunities to mate and father more offspring.You believe that having longer hair is adaptive to these males.You should _____.

Which of the following situations could not lead to evolution via natural selection?

Figure 24.1 The following question(s)are based on information in Hopi E.Hoekstra,Kristen E.Drumm,and Michael W.Nachman,"Ecological Genetics of Adaptive Color Polymorphism in Pocket Mice: Geographic Variation in Selected and Neutral Genes," Evolution 58(6),2004: 1329-41. -Refer to Figure 24.1.In their investigation of natural selection on Mc1r alleles (the gene that determines coat color)in Arizona pocket mice,Hoekstra et al.determined the frequency of the D and d alleles in each population.They also determined the frequency of alleles for two neutral mitochondrial DNA genes (genes that do not affect and are not linked to coat color).Why did the researchers include the mitochondrial DNA genes as part of their experimental design?

Parasitic species tend to have simple morphologies.Which of the following statements best explains this observation?

Figure 24.2 -The distribution of pocket-mouse coat colors in several Arizona populations is associated with substrate color.Some populations live on light-colored granite substrate,and others live on dark volcanic rock.In Figure 24.2,chart A shows the frequency of the melanic (dark)coat phenotype across six populations.Populations C,D,and E live on dark volcanic rock;populations A,B,and F live on light-colored granite.Chart B shows the frequency of the Melanocortin-1 receptor (Mc1r)allele across these populations.The Mc1r alleles,D and d,differ by four amino acids;mice with DD and Dd genotypes have dark coats,whereas mice with dd genotype are light colored.Which of the following statements best interprets the results shown in charts A and B?

Explain how one of the following supports the idea that species change through time: artificial selection,extinction,transitional forms,vestigial traits,antibiotic resistance.