Exam 21: The Evolution of Populations

Anopheles mosquitoes,which carry the malaria parasite,cannot live above elevations of 5,900 feet.In addition,oxygen availability decreases with higher altitude.Consider a hypothetical human population that is adapted to life on the slopes of Mt.Kilimanjaro in Tanzania,a country in equatorial Africa.Mt.Kilimanjaro's base is about 2,600 feet above sea level,and its peak is 19,341 feet above sea level.If the incidence of the sickle-cell allele in the population is plotted against altitude (feet above sea level),which of the following distributions is most likely,assuming little migration of people up or down the mountain?

If,on average,46% of the loci in a species' gene pool are heterozygous,then the average homozygosity of the species should be

Which of the following is correct about genetic variation?

Which statement about the beak size of finches on the island of Daphne Major during prolonged drought is true?

There are 25 individuals in population 1,all with genotype AA,and there are 40 individuals in population 2,all with genotype aa.Assume these populations are located far from each other and that their environmental conditions are very similar.Based on the information given here,the observed genetic variation most likely resulted from

Please use the following information to answer the question(s)below. -Examining the figure,which type of selection has two peaks of frequency of individuals?

Blue light is a portion of the visible spectrum that penetrates deep into bodies of water.Ultraviolet (UV)light,though,can penetrate even deeper.A gene within a population of marine fish that inhabits depths from 500 m to 1,000 m has an allele for a photopigment that is sensitive to UV light and another allele for a photopigment that is sensitive to blue light.Which of the graphs in Figure 21.1 best depicts the predicted distribution of these alleles within a population if the fish that carry these alleles prefer to locate themselves where they can see best? Figure 21.1

When evolution occurred on the Galápagos Islands,the finch beaks

When using the Hardy-Weinberg equilibrium model,we assume that

Figure 21.3 In a very large population,a quantitative trait has the distribution pattern shown in Figure 21.3.If the curve in Figure 21.3 shifts to the left or to the right,there is no gene flow,and the population size consequently increases over successive generations.Which of the following is (are)probably occurring?

It is estimated by a wide body of scientists that in recent decades we have begun another mass extinction event on Earth.Amphibians in particular have been in decline,sometimes due to climate change,and they therefore provide a possible early sign of dramatic biodiversity change to come.With respect to climate change and natural selection acting upon a population of one species of frog in a tropical rain forest,mutations of DNA sequences of the frog genome that are inherited by offspring

In a Hardy-Weinberg population with two alleles,A and a,that are in equilibrium,the frequency of the allele a is 0.3.What is the frequency of individuals that are homozygous for this allele?

What is the result of adaptive evolution?

In a population of 200 seagulls,dark brown feathers are dominant to having only white feathers.If 160 of the 200 seagulls have brown feathers,what is the frequency of seagulls that are homozygous dominant?

The same gene that causes various coat patterns in wild and domesticated cats also causes a cross-eyed condition in these cats,the cross-eyed condition being slightly maladaptive.In a hypothetical environment,the coat pattern that is associated with crossed eyes is highly adaptive,with the result that both the coat pattern and the cross-eyed condition increase in a feline population over time.Which statement is supported by these observations?

Why is the Hardy-Weinberg model useful?

How can gene flow improve adaptation of population?

No two people are genetically identical,except for identical twins.The main source of genetic variation among human individuals is

Please use the following information to answer the question(s)below. In the year 2500,five male space colonists and five female space colonists (all unrelated to each other)settle on an uninhabited Earthlike planet in the Andromeda galaxy.The colonists and their offspring randomly mate for generations.All 10 of the original colonists had free earlobes,and 2 were heterozygous for that trait.The allele for free earlobes is dominant to the allele for attached earlobes. -Which of these is closest to the allele frequency in the founding population?

Why don't similar genotypes always produce the same phenotype?