Exam 22: Descent With Modification: a Darwinian View of Life

During drought years on the Galapagos, small, easily eaten seeds become rare, leaving mostly large, hard-cased seeds that only birds with large beaks can eat. If a drought persists for several years, what should one expect to result from natural selection?

Which of the following must exist in a population before natural selection can act upon that population?

What was the prevailing notion prior to the time of Lyell and Darwin?

Over evolutionary time, many cave-dwelling organisms have lost their eyes. Tapeworms have lost their digestive systems. Whales have lost their hind limbs. How can natural selection account for these losses?

Within a few weeks of treatment with the drug 3TC, a patient's HIV population consists entirely of 3TC-resistant viruses. How can this result best be explained?

Charles Darwin was the first person to propose

Darwin's mechanism of natural selection required long time spans in order to modify species. From whom did Darwin get the concept of Earth's ancient age?

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D. -If "x" indicates the location of fossils of two closely related species, then fossils of their most-recent common ancestor are most likely to occur in which stratum?

DNA sequences in many human genes are very similar to the sequences of corresponding genes in chimpanzees. The most likely explanation for this result is that

If two modern organisms are distantly related in an evolutionary sense, then one should expect that

The following questions refer to the evolutionary tree in Figure 22.2. The tree's horizontal axis is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species. -Evolutionary trees such as this are properly understood by scientists to be

To observe natural selection's effects on a population, which of these must be True?

During a study session about evolution, one of your fellow students remarks, "The giraffe stretched its neck while reaching for higher leaves; its offspring inherited longer necks as a result." Which statement is most likely to be helpful in correcting this student's misconception?

Which of the following pairs of structures is least likely to represent homology?

Which of the following statements is an inference of natural selection?

Members of two different species possess a similar-looking structure that they use in a similar fashion to perform the same function. Which information would best help distinguish between an explanation based on homology versus one based on convergent evolution?

The theory of evolution is most accurately described as