Chapter 22

It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence that

island forms and mainland forms descended from common ancestors.

Given a population that contains genetic variation, what is the correct sequence of the following events, under the influence of natural selection? 1. Well-adapted individuals leave more offspring than do poorly adapted individuals. 2. A change occurs in the environment. 3. Genetic frequencies within the population change. 4. Poorly adapted individuals have decreased survivorship.

2 → 4 → 1 → 3

Which of the following pieces of evidence most strongly supports the common origin of all life on Earth?

All organisms use essentially the same genetic code.

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?

Characteristics acquired during an organism's life are generally not passed on through genes.

Natural selection is based on all of the following except

individuals adapt to their environments during their lifetime and, thereby, evolve.

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?

More small-beaked birds dying than larger-beaked birds. The offspring produced in subsequent generations have a higher percentage of birds with large beaks.

Which one of the following statements is true?

Natural selection works on variation already present in a population.

Which statement best describes the evolution of pesticide resistance in a population of insects?

Offspring of insects that are genetically resistant to the pesticide become more abundant as the susceptible insects die off.

Which of the following represents an idea that Darwin learned from the writings of Thomas Malthus?

Populations tend to increase at a faster rate than their food supply normally allows.

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?

Under particular circumstances that persisted for long periods, each of these structures presented greater costs than benefits.

Charles Darwin was the first person to propose

a mechanism for evolution that was supported by evidence

Which of the following is NOT a requirement of natural selection?

an environment that never changes

The theory of evolution is most accurately described as

an overarching explanation, supported by much evidence, for how populations change over time.

Your family is taking a long driving vacation across the midwestern and western United States. As you travel, you notice that the flowers, birds, and trees of the Midwest and the Rocky Mountains are very different. As you ponder why, you remember that such differences in the distribution of species are part of the field of ______.

biogeography

Homology is evidence of ______.

common ancestry

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

genetic variation among individuals

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

humans and chimpanzees share a relatively recent common ancestor.

In Darwin's thinking, the more closely related two different organisms are, the

more recently they shared a common ancestor.

In The Origin of Species, Darwin argued that the mechanism of descent with modification was _____.

none of the above

Natural selection results in ______.

offspring adapted to their current environment