BILD 3: Quiz 3

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

54%

There are those who claim that the theory of evolution cannot be true because the apes, which are supposed to be closely related to humans, do not likewise share the same large brains, capacity for complicated speech, and tool-making capability. They reason that if these features are generally beneficial, then the apes should have evolved them as well. Which of these provides the best argument against this misconception?

Advantageous alleles do not arise on demand.

How many of these statements regarding populations are true? 1. Mature males and females of a population can interbreed with each other. 2. Populations are sometimes geographically isolated from other populations. 3. Biological species are made up of populations. 4. Members of a population tend to be genetically more similar to each other than to members of other populations. 5. Populations have genomes, but not gene pools.

Four of these statements are true.

What is true of natural selection?

Mutations occur at random; natural selection can preserve and distribute beneficial mutations.

Which one of the following will prevent significant genetic drift?

The population size is large.

After surviving a bottleneck, a population recovers to the point where it consists of as many individuals as it did prior to the bottleneck. Which of the following statements is most likely to apply to this population?

The postbottleneck population exhibits less genetic variation than the prebottleneck population.

Evolution

can happen whenever any of the conditions for Hardy-Weinberg equilibrium are not met

Genetic drift is the result of ______.

chance

The most immediate effect of sexual displays and contests in animals (such as bighorn sheep bashing their heads together) is:

differential mating success

Which of the following is most likely to produce an African butterfly species in the wild whose members have one of two strikingly different color patterns?

disruptive selection

The restriction enzymes of bacteria protect the bacteria from successful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not vulnerable to these restriction enzymes because bacterial DNA is methylated. This situation selects for bacteriophages whose genomes are also methylated. As new strains of resistant bacteriophages become more prevalent, this in turn selects for bacteria whose genomes are not methylated and whose restriction enzymes instead degrade methylated DNA. The outcome of the conflict between bacteria and bacteriophage at any point in time results from

frequency-dependent selection.

When imbalances occur in the sex ratio of sexual species that have two sexes (i.e., other than a 50:50 ratio), the members of the minority sex often receive a greater proportion of care and resources from parents than do the offspring of the majority sex. This is most clearly an example of

frequency-dependent selection.

Over time, the movement of people on Earth has steadily increased. This has altered the course of human evolution by increasing

gene flow

The founder effect differs from a population bottleneck in that the founder effect ______.

involves the isolation of a small colony of individuals from a larger population

Over the past 60 years, many amphibian species have experienced significant population declines and some species have become extinct. Scientists suspected that local human activities such as the destruction of wetlands, regional pollution, and deforestation were the main reasons for these losses. However, research over the past 20 years reveals significant amphibian population declines in protected areas of the world, such as nature preserves and parks. These global declines suggest widespread problems including increased ultraviolet radiation, acid rain, and disease. In Switzerland, for example, 14 of the 20 native amphibian species are threatened with extinction. When most populations of a wide-ranging amphibian species are lost and the few remaining populations are widely separated, we expect to see that ______.

gene flow between populations is reduced

Although each of the following has a better chance of influencing gene frequencies in small populations than in large populations, which one most consistently requires a small population as a precondition for its occurrence?

genetic drift

Gene flow is accomplished by ______.

migration

Over the past 60 years, many amphibian species have experienced significant population declines and some species have become extinct. Scientists suspected that local human activities such as the destruction of wetlands, regional pollution, and deforestation were the main reasons for these losses. However, research over the past 20 years reveals significant amphibian population declines in protected areas of the world, such as nature preserves and parks. These global declines suggest widespread problems including increased ultraviolet radiation, acid rain, and disease. In Switzerland, for example, 14 of the 20 native amphibian species are threatened with extinction. Chytridiomycosis is a fungal disease first identified in 1998 as a cause of massive amphibian deaths. In some severely impacted populations, a few individuals have survived, perhaps because of some natural resistance. If these resistant individuals continue to survive and prosper, new resistant populations might emerge. This would be an example of ______.

natural selection

A proficient engineer can easily design skeletal structures that are more functional than those currently found in the forelimbs of such diverse mammals as horses, whales, and bats. The actual forelimbs of these mammals do not seem to be optimally arranged because

natural selection is generally limited to modifying structures that were present in previous generations and in previous species.

Most Swiss starlings produce four to five eggs in each clutch. Starlings producing fewer, or more, than this have reduced fitness. Which of the following terms best describes this situation?

stabilizing selection