Bio Ch 22

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

evolutionary tree in Figure 22.2. The horizontal axis of the cladogram depicted below 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. 42) According to this tree, what percent of the species seem to be extant (in other words, not extinct)?

66%

Which of these conditions should completely prevent the occurrence of natural selection in a population over time?

All variation between individuals is due only to environmental factors.

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.

Which of the five common ancestors, labeled V-Z, has given rise to the greatest number of species, both extant and extinct?

Both X and Y can be considered to have given rise to the greatest number of extant and extinct species.

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D. 38) 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?

C

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.

Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta and a third species (Z) is placed in the genus Elephas. Assuming this classification reflects evolutionary relatedness, which of the following is the most accurate phylogenetic tree?

D

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

Earth is a few thousand years old, and populations are unchanging.

If Darwin had been aware of genes, and of 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.

What must be true of any organ that is described as vestigial?

It must be homologous to some feature in an ancestor.

In the mid-1900s, the Soviet geneticist Lysenko believed that his winter wheat plants, exposed to ever-colder temperatures, would eventually give rise to ever more cold-tolerant winter wheat. Lysenko's attempts in this regard were most in agreement with the ideas of

Lamarck

Which pair would probably have agreed with the process that is depicted by this tree?

Lamarck and Wallace

The upper forelimbs of humans and bats have fairly similar skeletal structures, whereas the corresponding bones in whales have very different shapes and proportions. However, genetic data suggest that all three kinds of organisms diverged from a common ancestor at about the same time. Which of the following is the most likely explanation for these data?

Natural selection in an aquatic environment resulted in significant changes to whale forelimb anatomy.

DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Today, instead, DDT is largely useless against many insects. Which of these would have been required for this pest eradication effort to be successful in the long run?

None of the individual insects should have possessed genomes that made them resistant to DDT.

Which of the following is not an observation or inference on which natural selection is based?

Poorly adapted individuals never produce offspring.

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.

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.

Which of the following observations helped Darwin shape his concept of descent with modification?

South American temperate plants are more similar to the tropical plants of South America than to the temperate plants of Europe.

Currently, two extant elephant species (X and Y) are placed in the genus Loxodonta, and a third species (Z) is placed in the genus Elephas. Thus, which statement should be true?

Species X and Y share a greater number of homologies with each other than either does with species Z.

Which of the following statements most detracts from the claim that the human appendix is a completely vestigial organ?

The appendix has a substantial amount of defensive lymphatic tissue.

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 two species share many proteins in common, and the nucleotide sequences that code for these proteins are almost identical.

About 13 different species of finches inhabit the Galápagos Islands today, all descendants of a common ancestor from the South American mainland that arrived a few million years ago. Genetically, there are four distinct lineages, but the 13 species are currently classified among three genera. The first lineage to diverge from the ancestral lineage was the warbler finch (genus Certhidea). Next to diverge was the vegetarian finch (genus Camarhynchus), followed by five tree finch species (also in genus Camarhynchus) and six ground finch species (genus Geospiza). 48) If the six ground finch species have evolved most recently, then which of these is the most logical prediction?

Their genomes should be more similar to each other than are the genomes of the five tree finch species.

If the bacterium Staphylococcus aureus experiences a cost for maintaining one or more antibiotic-resistance genes, then what should happen in environments from which antibiotics are missing?

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

Which of the following statements best describes theories?

They are supported by, and make sense of, many observations.

What is true of pseudogenes?

They are vestigial genes.

Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are

Two of the responses above are correct.

) A biologist studied a population of squirrels for 15 years. During that time, the population was never fewer than 30 squirrels and never more than 45. Her data showed that over half of the squirrels born did not survive to reproduce, because of both competition for food and predation. In a single generation, 90% of the squirrels that were born lived to reproduce, and the population increased to 80. Which inference(s) about this population might be true?

Two of the statements above are correct.

Structures as different as human arms, bat wings, and dolphin flippers contain many of the same bones, these bones having developed from very similar embryonic tissues. How do biologists interpret these similarities?

Two of the statements above are correct.

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.

Which of the five common ancestors, labeled V-Z, has been least successful in terms of the percent of its derived species that are extant?

W

Which of the five common ancestors, labeled V-Z, has been most successful in terms of the percent of its derived species that are extant?

Z

Charles Darwin was the first person to propose

a mechanism for evolution that was supported by evidence.

If one wanted to find the largest number of endemic species, one should visit which of the following geological features (assuming each has existed for several millions of years)?

an isolated ocean island in the tropics

A 14th species that descended from the original ancestral finch, the Cocos Island finch, is endemic to its namesake island, located 550 km off Costa Rica. The Cocos Island finch is genetically much more similar to the tree finches than is the vegetarian finch, yet it is classified in its own genus Pinarolaxias. Moreover, the Cocos Island finch and the vegetarian finch are the two finch species that are most genetically different from the ancestral Galápagos finch. Thus, if classification is to reflect evolutionary relationships, the vegetarian finch should

be placed in its own genus

Of the following anatomical structures, which is homologous to the bones in the wing of a bird?

bones in the flipper of a whale

The role that humans play in artificial selection is to

choose which organisms breed, and which do not.

Which of the following is the most accurate summary of Cuvier's consideration of fossils found in the vicinity of Paris?

extinction of species yes; evolution of new species no

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

genetic variation among individuals

) Both ancestral birds and ancestral mammals shared a common ancestor that was terrestrial. Today, penguins (which are birds) and seals (which are mammals) have forelimbs adapted for swimming. What term best describes the relationship of the bones in the forelimbs of penguins and seals, and what term best describes the flippers of penguins and seals?

homologous; analogous

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.

The rise of methicillin-resistant Staphylococcus aureus (MRSA) can be considered to be an example of artificial selection because

humans synthesize methicillin and create environments in which bacteria frequently come into contact with methicillin.

Evolutionary trees such as this are properly understood by scientists to be

hypotheses

Natural selection is based on all of the following except

individuals adapt to their environments and, thereby, evolve.

According to a 1999 study, the vegetarian finch is genetically no more similar to the tree finches than it is to the ground finches, despite the fact that it is placed in the same genus as the tree finches. Based on this finding, it is reasonable to conclude that the vegetarian finch

is no more closely related to the tree finches than it is to the ground finches, despite its classification.

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.

A high degree of endemism is most likely in environments that are

isolated and heterogeneous.

In a hypothetical environment, fishes called pike-cichlids are visual predators of algae-eating fish (in other words, they locate their prey by sight). If a population of algae-eaters experiences predation pressure from pike-cichlids, which of the following is least likely to be observed in the algae-eater population over the course of many generations?

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

The following questions refer to the evolutionary tree in Figure 22.2. The horizontal axis of the cladogram depicted below 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. How many separate species, both extant and extinct, are depicted in this tree?

six

The following questions refer to Figure 22.1, which shows an outcrop of sedimentary rock whose strata are labeled A-D. 39) If x indicates the fossils of two closely related species, neither of which is extinct, then their remains may be found in how many of these strata?

two strata

With what other idea of his time was Cuvier's theory of catastrophism most in conflict?

uniformitarianism

Which of Darwin's ideas had the strongest connection to Darwin having read Malthus's essay on human population growth?

struggle for existence

Catastrophism, meaning the regular occurrence of geological or meteorological disturbances (catastrophes), was Cuvier's attempt to explain the existence of

the fossil record.

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

they should share fewer homologous structures than two more closely related organisms.