chapter 22

example of fossil record

-discovery of shells of extinct species -discovery of transitional forms in horses

Which of the following observations led to Darwin's major inferences?

-members of a population very in their heritable traits -although organisms can produce huge numbers of offspring, many of these offspring do not survive

example of homology

-similarities in mammalian forelimbs -same genetic code in fireflies and tobacco plants -vestigial pelvis in right whales

example of biogeography

-the high concentration of marsupial species in Australia -similarity of endemic island species to nearby mainland species

Varieties of Staphylococcus aureus that are resistant to the drug methicillin _____.

-were strongly selected for as methicillin became widely used to treat bacterial infections -already existed in the population before methicillin was developed

Evolutionary trees that go back 100,000 of years are properly understood by scientists to be

hypotheses

From his observations of organisms in the Galapagos islands, Darwin reasoned that _____.

organisms had adapted to new environments, giving rise to new species

Charles Darwin

proposed natural selection as the mechanism of evolution

If Darwin had been aware of genes and their typical mode of transmission to subsequent generations, with which statement would he most likely have been in agreement?

If natural selection can change one gene's frequency in a population over the course of generations then, given enough time and enough genes, natural selection can cause sufficient genetic change to produce new species from old ones.

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 are descended from mainland forms

DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Instead, DDT is largely useless against many insects. Which of these would have prevented this evolution of DDT resistance in insect pests?

None of the insect pests would have genetic variations that resulted in DDT resistance.

Logically, which of these should cast the most doubt on the relationships depicted by an evolutionary tree?

Relationships between DNA sequences among the species did not match relationships between skeletal patterns.

Within six months of effectively using methicillin to treat S. aureus infections in a community, all new infections were caused by MRSA. How can this result best be explained?

Some drug-resistant bacteria were present at the start of treatment, and natural selection increased their frequency.

In 1959, doctors began using the powerful antibiotic methicillin to treat infections of Staphylococcus aureus, but within two years, methicillin-resistant strains of S. aureus (MRSA) appeared. How did the resistant strains of S. aureus emerge?

Staphylococcus aureus bacteria that were able to synthesize cell walls using a protein that was not affected by methicillin survived the methicillin treatments and reproduced at higher rates than did other individuals. Over time, these resistant individuals became increasingly common.

A group of small fish live in a lake with a uniformly light-brown sandy bottom. Most of the fish are light brown, but about 10% are mottled. This fish species is often prey for large birds that live on the shore. A construction company dumps a load of gravel in the bottom of the lake, giving it a mottled appearance. Which of these statements presents the most accurate prediction of what will happen to this fish population?

The proportion of mottled fish will increase over time.

Members of two different species possess a similar-looking structure that they use in a similar way to perform about the same function. Which of the following would suggest that the relationship more likely represents homology instead of convergent evolution?

The two species share many proteins

If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, what would happen in environments that lack antibiotics?

These bacteria would be outcompeted and replaced by bacteria that have lost these genes.

example of direct observation of evolutionary change

development of drug resistance in bacteria

A challenge to traditional (pre-1860) ideas about species came from embryology, when it was discovered that _____.

embryos of dissimilar organisms, such as sharks and humans, resemble each other

In a hypothetical environment, fishes called pike-cichlids are visual predators of large, adult algae-eating fish (in other words, they locate their prey by sight). The population of algae-eaters experiences predatory pressure from pike-cichlids. Which of the following is least likely to result in the algae-eater population in future generations?

selection for larger female algae-eaters, bearing broods composed of more, and larger, young

In Darwin's tree of life, each fork in the tree represents ________.

the most recent common ancestor of the subsequent branches